[Federal Register Volume 61, Number 20 (Tuesday, January 30, 1996)]
[Rules and Regulations]
[Pages 3118-3173]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-1584]
[[Page 3117]]
_______________________________________________________________________
Part III
Department of Health and Human Services
_______________________________________________________________________
Food and Drug Administration
_______________________________________________________________________
21 CFR Part 172
Food Additives Permitted for Direct Addition to Food for Human
Consumption: Olestra; Final Rule
Federal Register / Vol. 61, No. 20 / Tuesday, January 30, 1996 /
Rules and Regulations
[[Page 3118]]
DEPARTMENT OF HEALTH AND HUMAN SERVICES
Food and Drug Administration
21 CFR Part 172
[Docket No. 87F-0179]
Food Additives Permitted for Direct Addition to Food for Human
Consumption; Olestra
AGENCY: Food and Drug Administration, HHS.
ACTION: Final rule.
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SUMMARY: The Food and Drug Administration (FDA) is amending the food
additive regulations to provide for the safe use of sucrose esterified
with medium and long chain fatty acids (olestra) as a replacement for
fats and oils. This action is in response to a petition filed by the
Procter & Gamble Co.
DATES: The regulation is effective January 30, 1996. Submit written
objections and requests for a hearing by February 29, 1996. Submit
written comments on the labeling requirement (Sec. 172.867(c)) by April
1, 1996. The Director of the Office of the Federal Register approves
the incorporations by reference in accordance with 5 U.S.C. 552(a) and
1 CFR part 51 of certain publications at 21 CFR 172.867, effective
January 30, 1996.
ADDRESSES: Submit written objections to the Dockets Management Branch
(HFA-305), Food and Drug Administration, 12420 Parklawn Dr., rm. 1-23,
Rockville, MD 20857.
FOR FURTHER INFORMATION CONTACT: Helen R. Thorsheim, Center for Food
Safety and Applied Nutrition (HFS-216), Food and Drug Administration,
200 C St. SW., Washington, DC 20204, 202-418-3092.
SUPPLEMENTARY INFORMATION:
Table of Contents
I. Introduction
A. Safety Testing--Background
1. Legal Context of the Safety Evaluation
2. Dietary Context of the Safety Evaluation
B. Toxicological Studies--Overview
C. Nutritional Impact Studies--Overview
D. GI Effects--Overview
E. FDA's Decision Process
II. Identity and Use
A. Manufacturing Processes
B. Constituents
C. Specifications
D. Stability
E. Use and Intended Technical Effect
F. Estimated Daily Intake for Olestra (EDI)
III. Toxicity Data--Discussion and Evaluation
A. Absorption, Distribution, Metabolism, and Elimination.
1. Rat Studies
2. Guinea Pig Studies
3. Mini-Pig Studies
B. Genetic Toxicity Studies
C. Animal Toxicity Studies
1. Teratogenicity studies
2. Subchronic and chronic feeding studies
a. Ninety-day subchronic olestra feeding study in rats
b. Two-year carcinogenicity studies in rats
c. Two-year chronic toxicity and carcinogenicity studies in mice
d. Dog feeding studies
D. Toxicology summary
IV. Effect of Olestra on Absorption of Drugs
A. Effect of Olestra on the Absorption of Selected Lipophilic Drugs
(EC-40)
B. Effect of Olestra on the Absorption of Selected Lipophilic Drugs
(EC-41)
C. Effect of Olestra on Drug Bioavailability (EC-42)
D. Effect of Olestra on the Systemic Levels of Steroidal Hormones
in Women Taking Oral Contraceptives (EC-51)
E. Summary
V. Nutritional Studies
A. Issues Associated with Olestra
B. Effects of Olestra on Fat-Soluble Vitamins
1. Primary Human Studies
a. Eight-week DR study design
b. Eight-week VR study design
c. Results and conclusions from primary human studies
i. Vitamin A
ii. Vitamin E
iii. Vitamin D
iv. Vitamin K
v. Carotenoids
2. Other Human Studies
a. Six-week vitamin D/K study
b. Sixteen-week vitamin E study
c. Vitamin A/Fat Study
3. Pig Studies
a. Study design of the 12-, 26-, and 39-week studies
i. Twelve-week DR Study
ii. Twelve-week VR Study
iii. Twenty-six week DR/VR Study
iv. Thirty-nine week VR Study
b. Study design of the 4-week DC study
c. Results and conclusions from pig studies
i. Vitamin A
ii. Vitamin E
iii. Vitamin D
a. Petitioner conclusions
b. FDA Conclusions
iv. Vitamin K
4. Overall Conclusions Regarding Olestra's Effects on Fat-Soluble
Vitamins
a. Consumption scenarios
b. Vitamin A
c. Vitamin E
d. Vitamin D
e. Vitamin K
i. Petitioner conclusions
ii. FDA conclusions
f. Carotenoids
i. Data and information regarding carotenoids
ii. FDA's evaluation of olestra's effects on carotenoids
C. Effects of Olestra on Water-Soluble Nutrients that are Hard-to-
Absorb or Limited in Diet
1. Results and Conclusions from Human Studies
a. Vitamin B12
b. Iron
c. Folate
d. Zinc
2. Results and Conclusions from Pig Studies
a. Vitamin B12
b. Iron
c. Folate
d. Zinc-
e. Calcium
3. Overall Conclusions Regarding Olestra's Effects on Water-Soluble
Nutrients
a. Vitamin B12
b. Folate and Iron
c. Zinc
d. Calcium
VI. Effect of Olestra on the Gastrointestinal (GI) Tract
A. Introduction
B. Effect of Olestra on GI Symptoms
1. Study of GI Symptoms in 8-week Studies in Normal Subjects
a. Petitioner's evaluation of GI symptoms
b. FDA's evaluation of the GI symptoms
2. GI Symptoms in the Oil Loss Study
a. Effect of olestra stiffness on passive oil loss
b. Effect of olestra stiffness on OIT
c. Effect of olestra stiffness on GI symptoms
3. Study of Selected Fecal Parameters in Subjects Consuming Olestra
a. Study design
b. Petitioner conclusions
C. FDA Conclusions
4. Study in Patients with Inflammatory Bowel Disease
5. GI Symptoms in Young Children
C. Effect of Olestra on Intestinal Microflora Metabolism
1. Effect of Olestra on Breath Gas and Microflora-Associated
Characteristics
2. Potential for Intestinal Microflora to Metabolize Olestra
D. Effect of Olestra on Bile Acid Metabolism
E. Overall Conclusions on Effects on the GI Tract
[[Page 3119]]
VII. Labeling of Foods Containing Olestra
A. Labeling Authority
B. Labeling with Respect to GI Effects
C. Labeling with Respect to Effects on Nutrients
D. FAC Discussions Regarding Labeling
1. GI Effects
2. Fat-Soluble Vitamins and Carotenoids
E. Agency Conclusions Regarding Labeling of Foods Containing
Olestra
VIII. Response to Comments
A. Comments on Procedures
B. Substantive Comments
IX. Environmental Impact Considerations
X. FDA's Overall Conclusions
XI. Administrative Record and Inspection of Documents
XII. Objections
XIII. References
I. Introduction
Olestra, also called sucrose polyester, is the common name for a
mixture of substances formed by chemical combination of sucrose with
six, seven, or eight fatty acids. The fatty acids, bound to sucrose by
ester bonds, are of the type commonly found in edible oils and fats.
Olestra has physical properties similar to those of natural fats.
Olestra's particular physical properties depend on the specific fatty
acids used and the degree of esterification.
The Procter & Gamble Co., 6071 Center Hill Rd., Cincinnati, OH
45224-1703 (the petitioner), submitted a petition to FDA on April 15,
1987, for the use of olestra in shortenings and oils as a calorie-free
replacement for fats and oils. The petition (FAP 7A3997) was filed on
May 7, 1987. In a notice in the Federal Register of June 23, 1987 (52
FR 23606), FDA announced that the food additive petition had been filed
by Procter & Gamble, proposing the issuance of a food additive
regulation providing for the safe use of sucrose esterified with medium
and long chain fatty acids as a replacement for fats and oils. On July
6, 1990, the petitioner amended the petition to limit the intended use
of olestra to a 100 percent replacement for conventional fats in the
preparation of savory snacks (i.e., snacks that are salty or piquant
but not sweet, such as potato chips, cheese puffs and crackers). During
the course of the petition evaluation, the petitioner also amended the
proposed specifications that describe the additive.
In the Federal Register of October 17, 1995 (60 FR 53740), FDA
announced that a public meeting of the agency's Food Advisory Committee
(the FAC) and a working group of the FAC would be held on November 14
through 17, 1995. The working group was asked to discuss and comment on
whether all relevant issues associated with olestra had been addressed
(Ref. 1). The discussion covered all aspects of the safety review of
olestra, including nutrient effects and compensation, gastrointestinal
effects, and labeling (Ref. 2\1\).
\1\The transcript of the Olestra Working Group and full Food
Advisory Committee meetings are provided as reference. Throughout
the preamble to this final rue, reference is made to comments of
Committee members and presenters to the Committee; footnotes
indicate the transcript volum and page numbers of these. The
affiliation and credentials of the commenter are also described.
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In the Federal Register of November 16, 1995 (60 FR 57586), FDA
announced that it would consider public comments on the petition,
including comments on the proceedings before the FAC, only if filed on
or before December 1, 1995. This action allowed the agency to identify
precisely which data and information to consider in making its decision
on the petition. This measure was necessary to facilitate the agency's
decision making process and to come to closure on the petition. By
letter dated December 8, 1995, FDA extended to December 21, 1995, the
time by which such comments could be submitted. This extension was in
response to a request of the Center for Science in the Public Interest
(CSPI).\2\
\2\On October 25, 1995, CSPI submitted a comment to the olestra
petition entitiled ``White Paper on Olestra'' (the White Paper).
(CSPI subsequently submitted revised versions of the White Paper on
November 2 and 3, 1995.) The November 3, 1995, White Paper was
provided to the Olestra Working Group and FAc members for
consideration at the meetins of November 14-17, 1995 (Ref.3). In
addition, the authors of the White Paper, Drs. Myra Karstadt and
Michael Jacobson, presented data from the White Paper on all of the
issues covered in the White Papers, namely, (1) consumption
estimates, (2) effect of olestra on carotenoids, (3) effect of
supplementation of olestra with vitamin K on coumadin therpay, (4)
effect of olestra on GI symptoms, and (5) animal carcinogenicity
studies.
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A. Safety Testing-Background
1. Legal Context of the Safety Evaluation
Section 409 of the act (21 U.S.C. 348), sets forth the statutory
requirements for approval of a food additive (21 U.S.C. 321(s)). With
the enactment of the Food Additives Amendment of 1958 (the Amendment),
Congress established a premarket approval system whereby the company
seeking to market a food additive must first obtain approval from FDA.
Through this mechanism, Congress sought to shield the public from
unsafe or potentially unsafe products.
Under section 409(c)(3) of the act, 21 U.S.C. 348(c)(3), FDA is not
to approve a food additive petition ``* * * if a fair evaluation of the
data before the Secretary\3\ * * * fails to establish that the proposed
use of the food additive, under the conditions of use to be specified
in the regulation, will be safe * * *. This provision is commonly
referred to as the ``general safety clause.''
\3\This decision has been delegated to the Commissioner of Food
and Drugs, 21 CFR 5.10(a)(1).
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By requiring that the data concerning a food additive ``establish''
safety, Congress squarely placed the burden of proving safety on the
sponsor of a food additive petition, in this case Procter & Gamble. FDA
need not prove that the additive is unsafe in order to deny approval.
The term ``safe'' is not defined in the act itself. The legislative
history of the Amendment makes clear, however, that a demonstration of
absolute harmlessness is not required to sustain the approval of a food
additive:
Safety requires proof of a reasonable certainty that no harm
will result from the proposed use of an additive. It does not-- and
cannot--require proof beyond any possible doubt that no harm will
result under any conceivable circumstance. This was emphasized
particularly by the scientific panel which testified before the
subcommittee. The scientists pointed out that it is impossible in
the present state of scientific knowledge to establish with complete
certainty the absolute harmlessness of any chemical substance.
H. Rept. No. 2284, 85th Cong., 2d sess. 4-5 (1958). Accord: S. Rept.
No. 2422, 85th Cong., 2d sess. 2 (1958). FDA regulations incorporate
the concept of safety articulated in the Amendment's legislative
history. 21 CFR 170.3(i). (``Safe'' means that ``* * * there is a
reasonable certainty in the minds of competent scientists that the
substance is not harmful under the intended conditions of use.'')
Although the concept of ``harm'' is central to the act's safety
standard, neither the statute, nor regulations implementing the food
additive provisions, define harm. Once again, however, congressional
intent is clear from the legislative history of the amendment.
Specifically, ``harm'' means the capacity to injure or otherwise damage
the health of individuals consuming the additive.+
The concept of safety used in this legislation involves the
question of whether a substance is hazardous to the health of man or
animal.
H. Rept. No. 2284, 85th Cong., 2d sess. 4 (1958). See also Letter from
Assistant Secretary of Health, Education, and Welfare Elliot L.
Richardson to Congressman Lister Hill, Chairman,
[[Page 3120]]
Senate Committee on Labor and Human Resources, dated July 29, 1958.
(``* * * in our opinion the bill is aimed at preventing the addition to
the food our people eat of any substances the ingestion of which would
expect to produce not just cancer but any disease or disability.'')
The concept of harm was discussed during the Olestra Working Group
and FAC meetings. One FAC member expressed the opinion that he would
consider an effect that is undesirable as harmful or adverse\4\.
However, the legislative history reflects that an effect is harmful if
it affects health, not if it is simply an undesirable or unexpected
effect that has no adverse health consequences.
\4\Statement of Dr. Dennis Hsieh. Dr. Hsieh is a professor of
environmental toxicology at the University of California at Davis.
Transcript of the November 14 to 17, 1995, meeting of FAC
(hereinafter Transcript), vol. 3, p. 40.
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The statute leaves the methods and criteria for interpreting data
up to the discretion and expertise of the agency. Congress did,
however, direct FDA to consider the following three factors:
(A) The probable consumption of the additive and of any substance
formed in or on food because of the use of the additive;
(B) The cumulative effect of such additive in the diet of man or
animals, taking into account any chemically or pharmacologically
related substance or substances in such diet; and
(C) Safety factors which in the opinion of experts qualified by
scientific training and experience to evaluate the safety of food
additives are generally recognized as appropriate for the use of animal
experimentation data. (21 U.S.C. 348(c)(5).)
In the case of olestra, the product's broad marketing potential and
expected consumption by persons of all ages, including children, are
aspects that have been considered in the safety evaluation.
Importantly, Procter & Gamble is not required to show, nor is FDA
permitted to consider, that olestra has benefits, health or otherwise,
for consumers of the additive. Again, the legislative history of the
Amendment is clear on this point.
The question of whether an additive produces such [a technical]
effect (or how much of an additive is required for such an effect)
is a factual one, and does not involve any judgement on the part of
the Secretary of whether such effect results in any added 'value' to
the consumer of such food or enhances the marketability from a
merchandising point of view.
S. Rept. No. 2422, 85th Cong., 2d sess. 7 (1958). Accord: H. Rept. No.
2284, 85th Cong., 2d sess. 6 (1958).
In summary, the general safety clause places on Procter & Gamble
the burden of proving that a fair evaluation of the data in the
administrative record establishes that there is a reasonable certainty
that olestra will not be harmful under the prescribed conditions of
use. Only if Procter & Gamble meets this burden can the food additive
be approved.
2. Dietary Context of Safety Evaluation
Olestra presents a different set of safety issues compared to most
food additives. For example, most substances can induce toxic effects
provided that the dose administered is sufficiently high. The primary
purpose of most safety testing is to determine the toxic dose and to
evaluate whether there is a sufficient margin of safety between the
highest dose that is not toxic and the expected human exposure.
Because olestra is intended to substitute for fat, a substantial
component of the diet, it is difficult, if not impossible, to feed
olestra to laboratory animals in amounts sufficiently high to allow use
of the 100-fold safety factor that is commonly used to ensure safety
(21 CFR 170.22), when evaluating animal studies. The use of a safety
factor is intended to account for the uncertainty of extrapolating from
toxicity data from animals to humans. (See 21 U.S.C. 348(c)(5)(c).) FDA
concludes that in the case of the olestra petition, the agency is
justified in not using the 100-fold safety factor for the following
reasons. First, no toxic effects from olestra consumption were observed
when olestra was fed atpara.levels up to 10 percent of the diet of
laboratory animals (as discussed in section III. of this document).
Second, olestra is not appreciably absorbed by the body and the
minuscule amount of material that is absorbed is metabolized to
substances (sucrose and fatty acids) that are further metabolized
normally in the body. Thus, no major component of olestra is available
to produce a toxic effect. Finally, a significant number of human
studies have been performed to assess the safety of olestra, which
assessment may be performed without the need for a safety factor.
The fact that olestra is not absorbed also means, however, that as
food components are absorbed from the intestine, the amounts of olestra
present in the intestine will become an increasingly larger fraction of
the total intestinal contents. Thus, the safety issues for olestra are
focused on effects in the intestine, including potential interference
with absorption of nutrients.
The petitioner completed the standard toxicological testing program
to demonstrate safety for a direct food additive, as outlined in FDA's
guidance on such testing (Ref. 4). However, to account for the possible
variations in composition, effects on composition due to heating, and
inherent difficulties in extrapolating from laboratory animals to
humans, the initial animal tests have been supplemented with a variety
of human and additional animal studies taking into account the
properties of olestra. In fact, since the original petition was
submitted inpara.1987, Procter & Gamble has submitted more than 50
additional safety studies for review. In 1992 and 1993, the pivotal
safety studies with regard to nutritional effects from the petitioned
use of olestra were submitted.
B. Toxicological Studies--Overview
The petition submitted to FDA consists of data and information from
toxicity studies in several animal species, including the rat, mouse,
dog, and rabbit. The toxicity data base includes a battery of three
mutagenicity/genotoxicity tests; subchronic feeding studies in mice,
rats, hamsters, and dogs; and reproduction/teratology testing in the
rat and rabbit. To determine whether olestra affects the structure and
function of the gastrointestinal (GI) tract, a series of absorption,
distribution, metabolism, and elimination (ADME) studies were conducted
in rats, mini-pigs, and guinea pigs.
C. Nutritional Impact Studies--Overview
The limited digestibility of olestra poses a number of nutrition
issues, including olestra's effect on fat-soluble vitamins and whether
these effects could be compensated for by the addition of an
appropriate amount of the affected vitamins. As a result, the
petitioner conducted several studies, including those listed below, in
both pigs and humans. Procter & Gamble conducted studies in swine
because they have a digestive system similar to humans and can be
evaluated for nutrient stores in the liver and bone. Five of the
studies that were carried out in swine are: (1) a 12-week dose-response
study (the 12-week DR study) of olestra on the status of
vitaminspara.A, D, E, and K, and on hard-to-absorb and limited-in-diet
nutrients; (2) a 12-week vitamin restoration study (the 12-week VR
study) to determine levels of vitamins A, D, and E needed to offset
olestra effects; (3) a 26-week dose-response and vitamin restoration
study (the 26-week DR/VR study) to extend
[[Page 3121]]
the findings of the 12-week DR and 12-week VR studies to longer times
and lower olestra intake levels; (4) a 39-week study (the 39-week VR
study) to confirm the effects of 0.25 percent olestra and added vitamin
A and E measured in the 26-week DR/VR study over a longer exposure
time; and (5) a 4-week dietary context study (the 4-week DC study) to
compare olestra's effects on vitamins A and E when olestra is consumed
either with the diet or between meals.
Procter & Gamble conducted studies of olestra in humans to
eliminate any uncertainty related to extrapolating from pigs and to
obtain subject reports on gastrointestinal effects. Those objectives
were pursued in several human studies including: Two clinical studies,
two studies in free-living subjects,\5\ and one short-term study
designed to assess olestra's effect on vitamin A and fat absorption
(the vitamin A/fat study). The two human clinical studies were an 8-
week study to determine the dose response of olestra on the status of
vitamins A, D, E, and K, and on hard-to-absorb and limited-in-diet
nutrients (the 8-week DR study) and an 8-week study to confirm the
compensation levels for vitamins A and E (the 8-week VR study). The
free-living studies were a 16-week study to assess the status of
vitamin E in subjects consuming 18 grams/day (g/d) olestra (the 16-week
vitamin E study) and a 6-week study to determine the effect of 20 g/d
olestra on vitamins D and K (the 6-week vitamin D/K study).
\5\Free-living subjects maintain their normal diets and eating
patterns except for consumption of the test article as instructed.
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D. GI Effects--Overview
The petitioner performed several studies to evaluate olestra's
effects on the gastrointestinal (GI) tract including the following. The
two clinical studies (the 8-week DR and 8-week VR studies) were used to
evaluate adverse gastrointestinal effects as reported by the test
subjects. In addition, the effect of olestra on intestinal microflora
was measured by conducting a breath gas expiration study. Several
studies were also conducted to evaluate olestra's effects on bile acid
metabolism and absorption. In order to determine olestra's effects, if
any, in an at-risk population, studies were conducted in inflammatory
bowel disease patients. Because some drugs are lipophilic (fat-soluble)
and may partition into (i.e., be partially absorbed by) olestra,
olestra's potential to affect absorption of drugs was also
investigated. In addition, because nonabsorbable liquid oil can
separate from other fecal material in the colon and leak through the
anal sphincter, a human clinical study was performed to determine the
relationship between olestra's stiffness and passive oil loss.
E. FDA's Decision Process
In light of the novel issues raised by the review of the olestra
data, FDA's Center for Food Safety and Applied Nutrition (CFSAN)
determined that it would be valuable to obtain additional expertise in
resolving certain issues that had been raised. A Regulatory Decision
Team (RDT) composed of senior FDA managers was established for the
purpose of recommending, to the Director of CFSAN, a decision on the
olestra food additive petition. In addition, FDA retained the services
of several scientific consultants from outside the agency to facilitate
the agency's deliberations.
As is the case with all food additive petitions, the olestra data
were reviewed by staff scientists. Because of the large number of
studies and the diverse nature of the information, each of these
scientists reviewed a portion of the total body of data on the
additive, focusing on his particular area of expertise. These staff-
level reviews, including any questions or issues raised by such
reviews, were subsequently considered by the RDT, assisted by the
outside consultants. In the RDT deliberations, an overall Center
position on olestra's safety was synthesized; in the process, issues
raised by individual reviewers were resolved, were determined to be not
significant, or were incorporated into the synthesized position. During
this deliberative process, the members of the RDT weighed the various
pieces of scientific information and applied their scientific judgement
as they developed an overall Center position.
After the conclusion of the RDT deliberations and the meetings with
consultants from outside the agency, FDA convened a public meeting of
its FAC and a special Olestra Working Group of the FAC on November 14
through 17, 1995, to undertake a scientific discussion of the agency's
evaluation of the safety data in the petition. The membership of the
standing Committee was supplemented with temporary members and
consultants to the Committee, representing scientific disciplines
appropriate to the evaluation of a macro-ingredient fat substitute.
At the Olestra Working Group meeting, Procter & Gamble presented a
summary of the data it considered adequate to establish the safety of
olestra, the experts with whom the agency had consulted presented their
views on the sufficiency of the information to assess the safety of
olestra, interested members of the public presented their opinions and
evaluations of the data, and FDA presented its evaluation of the data.
The Committee was asked to assess, in light of the state of the science
relative to macro food ingredients, whether all critical safety issues
with respect to the use of olestra in savory snack foods had been
addressed.
As set out in detail below, having completed its evaluation of the
data in the petition and having considered the deliberations of the
Olestra Working Group and the FAC, including all presentations to the
Committee, and the comments received on the petition, the agency is
amending the food additive regulations to permit the use of olestra in
place of fats and oils in prepackaged ready-to-eat savory snacks.
II. Identity and Use
Olestra is the common name for the mixture of sucrose esters formed
from the addition of six, seven, or eight fatty acids to the available
eight free hydroxyl moieties of sucrose. Saturated and unsaturated
fatty acids of chain length C12 to C20 and higher can be used to
manufacture olestra. The final product is defined by specifications
which include the fatty acid composition.-
The identity of sucrose octaester as the principal component of
olestra has been verified by infrared, mass, and nuclear magnetic
(proton and 13carbon) spectrometry (Ref. 5). The generalized structure
for olestra is set forth below.
BILLING CODE 4160-01-F
[[Page 3122]]
[GRAPHIC][TIFF OMITTED]TR30JA96.000
BILLING CODE 4160-01-C
[[Page 3123]]
A. Manufacturing Processes
Olestra is prepared by the addition of medium- and long-chain fatty
acid methyl esters to sucrose in the presence of catalysts. The
postsynthesis purification steps are the same as those generally
practiced in the edible oils industry. These purification steps depend
upon physical separations and do not involve chemical bond
rearrangement or the use of solvents or catalysts.
The methyl esters used to prepare olestra can be obtained by
procedures common in the food industry such as the reaction of refined
triglyceride oils with methanol in the presence of sodium methoxide or
from esterification of their fatty acids. The resulting esters are
washed with water to remove residual methanol, dried under vacuum, and
distilled. The fats and oils can be derived from a variety of edible
sources such as, but not limited to, soybean, palm, coconut, fully
hydrogenated rapeseed, and cottonseed.
Sucrose and the methyl esters are mixed with an alkali metal soap
of a long-chain fatty acid. A small amount of transesterification
catalyst such as an alkali metal (sodium or potassium) carbonate,
bicarbonate, hydride, or alkoxide is added and the mixture heated under
vacuum to withdraw the volatile methanol byproduct. Following the
reaction, excess methyl esters and free methanol are removed by
evaporation under vacuum. Standard steam deodorization removes free
fatty acids and odors. Different lots of olestra may be mixed to
achieve desired properties or to meet product specifications.
The manufacture of olestra can be well controlled, based upon the
petitioner's analysis of representative lots (Ref. 5).
B. Constituents
The principal trace constituents of olestra are collectively
identified as the unsaponifiable fraction, ranging in concentration
from 0.08 percent to 0.3 percent. These constituents are primarily
aliphatic hydrocarbons and plant sterols that naturally arise from the
edible triglyceride sources of fatty acids used in the synthesis of
olestra. In this respect, these trace constituents of olestra do not
differ from those found in typical edible oils. Additionally, difatty
ketones (DFK's), formed during its manufacture, are found as trace
constituents in olestra as consumed.
DFK's form in olestra during the alkaline rearrangement
manufacturing process. The DFK's that are present in olestra are a
family of compounds with a common general structure consisting of two
fatty acid chains with a central keto group. They are formed from
naturally occurring vegetable oil-derived fatty acids used to make
olestra. The length and degree of unsaturation of the fatty acid chains
are determined by the source oil used to make olestra.
Quantitative analysis of olestra by gas chromatography and mass
spectrometry of 15 typical lots of olestra determined that olestra
contains 36 to 416 parts per million (ppm) DFK's. The potential DFK
range of olestra was altered to 100 to 300 ppm when the method of
manufacture was updated. Qualitative analysis of soybean oil-based
olestra showed that the DFK's ranged from 31 to 35 carbons in length,
consistent with the predominance of C16 and C18 fatty acids
in soybean oil.
Identical analytical techniques showed that similar types
(C29-C35 fatty acid chain length), but lower levels, of DFK
are found in vegetables (5 to 86 ppm), cooked meat fat (0.15 to 2.73
ppm), and food-approved emulsifiers (10 to 55 ppm). Historically, the
once-common commercial practice of rearranging fats and oils by base-
catalyzed methods produced levels of DFK that exceeded 300 ppm. These
results show that olestra is an additional dietary source of those
DFK's that are now, and have been, commonly consumed in the food supply
(Ref. 6).
C. Specifications
Olestra comprises a range of possible compositions that can be
identified by a three-dimensional matrix defined by: (1) Fatty acid
chain length; (2) the degree of fatty acid unsaturation; and (3) the
distribution of full and partial esters of olestra. The petitioner has
proposed specifications that include ranges for fatty acid chain length
and degree of unsaturation to ensure functional products for use in
savory snacks. The specified range of esterification ensures the
nonabsorbable and noncaloric nature of the product.
Traditional edible oil specifications that ensure purity and safety
also are incorporated into the olestra specifications. These values
include specifications for free fatty acid content, total methanol
residues, water, residue on ignition, peroxide value, total heavy metal
content, and lead.
D. Stability
Olestra is stable under ambient and high-temperature storage
conditions. In all cases, olestra is at least as stable as
triglycerides with similar fatty acid composition.
Polymers form in both olestra and triglycerides during cooking,
purification, or storage, when olestra or triglycerides are exposed to
heat, moisture, and air. The polymers, comprised almost entirely of
dimers and trimers, form by cross-linking at points of unsaturation on
the fatty acid chains. This mechanism of cross-linking in olestra is
the same as that which occurs in triglycerides. The amount of polymer
found in olestra is less than that found in a conventional edible oil
stored under identical, controlled conditions.
Typical bulk lots of olestra were demonstrated to be as stable as
triglycerides of similar fatty acid composition when stored at room and
elevated temperatures (120 F) for up to 1 month. These olestra batches
were found to be stable based upon the lack of significant change in
fatty acid composition, ester distribution, free fatty acid levels,
polymer levels, and oxidative stability (Ref. 7).
Heating food fats in the presence of moisture and air results in
the production of decomposition byproducts. Such byproducts are removed
regularly from commercial cookers to maintain an effective frying
system under good manufacturing practice. Use of olestra for frying
savory snacks will similarly lead to production of byproducts. The
petitioner conducted research to determine the extent of byproduct
production from olestra compared to conventional frying fats, and to
determine whether unique byproducts would be formed.
A variety of analytical techniques were employed to characterize
the profile of byproducts formed during the heating of olestra and
conventional frying fats. The gross identity of the heated products was
determined by standard methods such as fatty acid composition, carbon
number profile, and peroxide value. In addition, comprehensive analyses
of changes to the fatty acid side chains were undertaken. Fatty acids
were methylated by transesterification, isolated by silica gel column
chromatography or solid phase extraction, and analyzed by a variety of
techniques including gas chromatography (GC), GC/mass spectrometry
(MS), two-dimensional GC/MS, and high performance liquid chromatography
(HPLC). This battery of tests provided an analytical sensitivity to
detect a component present in the heated oil at a level of 17 ppm
(equivalent to 0.05 ppm in the diet of 90th percentile consumers of
olestra) (Ref. 8).
For both olestra and conventional frying fats (triglycerides), the
predominant chemical changes that occur under frying conditions are
[[Page 3124]]
oxidation reactions on the fatty acid side chains (Ref. 8). The
principal byproducts of frying are polymers (dimers and trimers) which
are joined primarily by bonds between unsaturated fatty acid
components. Both olestra and conventional fats of similar fatty acid
composition undergo a similar number of polymerization reactions under
common heating conditions. For example, the amount of polymer increased
0.003 mole/100 g for olestra and 0.004 mole/100 g for a triglyceride of
similar fatty acid composition.
Levels of olestra and triglyceride polymers absorbed into the
cooked foods under worst-case conditions are similar and show that
there is no selective concentration in food. For example, polymer
levels in food fried in either olestra or triglyceride ranged from 4 to
6 percent of total lipid weight. These values correspond to the
concentration of olestra and triglyceride polymer in the bulk heated
oil phases (Ref. 8).
Baking conditions do not degrade olestra or triglyceride as readily
as frying conditions, even though soda crackers commercially prepared
with olestra may experience temperatures ranging from 250 to 350
deg.F. This is because crackers are exposed to such temperatures for
only a few minutes (not hours), and the temperature within the body of
the cracker can be expected to be substantially lower than the oven
temperature.
This stability in baking assessment was confirmed when both olestra
and a triglyceride of similar fatty acid composition were used to
prepare soda crackers, and the crackers were baked for 6 minutes at the
more common commercial temperature of about 250 deg.F. The neat (i.e.,
prior to baking) olestra and triglyceride were analytically
characterized, and the profiles compared to those obtained from the
fats extracted after the soda crackers were baked.
Unlike during frying, neither olestra nor the triglyceride formed
any measurable polymer during the 250 F baking (Ref. 9.). Consistent
with a lack of change in polymer content, results demonstrate that
neither olestra nor the triglyceride experienced any significant change
in primary structural composition (i.e., ester distribution for
olestra; or the tri-, di-, or monoglyceride profile for the
triglyceride).
The only notable change in both olestra and the triglyceride was a
slight increase in free fatty acid content. This latter effect is
expected because free fatty acids may be present in the cracker raw
ingredients, and the alkaline chemical leavening agents used in soda
cracker production can promote ester hydrolysis. The similarity of
changes in olestra and triglycerides during soda cracker baking is
consistent with the fact that the chemical changes in both products
take place on the fatty acids, and yield the same decomposition
products.
To test stability during storage after baking, both olestra and a
triglyceride of similar fatty acid composition were used to make soda
crackers, unflavored plain crackers, and unflavored snack crackers. All
products were packed in air to reflect current market practice, aged
under controlled temperatures and time to reflect common and worst-case
storage conditions, and analyzed for parent, polymer, and decomposition
products. The results demonstrate that the stability of olestra and
triglyceride were comparable under the conditions studied (Ref. 9).
FDA concludes that use of olestra in frying media for savory snacks
results in neither more nor different byproducts of the frying process
than currently experienced with conventional oils. Also, olestra is as
stable as triglyceride in crackers during baking and in baked crackers
stored under expected and worst-case conditions.
E. Use and Intended Technical Effect
Olestra is proposed for use as a calorie-free replacement for up to
100 percent of the conventional fats and oils used in the preparation
of savory snacks such as flavored and unflavored chips and crisps,
flavored and unflavored extruded snacks, and crackers. These uses
include substitution for fat for frying as well as sources of fat in
dough conditioners, oil sprays, and flavors. Olestra will function in
savory snacks as a texturizer and as a formulation aid (21 CFR
170.3(o)) at levels not in excess of that reasonably required to
produce its intended effect.
F. Estimated Daily Intake for Olestra (EDI)
When conducting a food additive safety evaluation, FDA typically
uses estimated 90th percentile chronic intakes. The petitioner has
provided a study of probable intake for olestra, completed by the
Market Research Corporation of America (MRCA), that contains sufficient
information to estimate both chronic and acute exposures to olestra.
The MRCA methodology estimates the daily consumption of olestra
from savory snacks for individuals by combining: (1) The individual's
frequency of consumption of savory snacks; (2) the average amount eaten
per eating occasion of that savory snack; and (3) the amount of olestra
in that savory snack. Eating occasion frequencies were determined from
14-day dietary diaries that were kept by heads of household. The amount
of food eaten per eating occasion was derived from the USDA's
Nationwide Food Consumption Surveys. The amount of olestra in snacks
was determined in the petitioner's laboratories.
The MRCA survey data show that at the 90th percentile, the probable
lifetime-averaged intake of olestra is 6.4 g/p/d. FDA believes however,
that it is appropriate to consider energy needs in estimating the daily
intake of olestra. Based on the assumption that consumers of olestra
will compensate for calories ``lost'' due to consumption of olestra by
increasing their intake of food (including olestra-containing snacks),
the agency has concluded that the lifetime-averaged EDI for olestra
should be increased by 10 percent to 7.0 g/p/d (Ref. 10).
Any effects of olestra on nutrients or nutrient absorption could be
exhibited during less than chronic exposure conditions. To evaluate
sub-chronic conditions, FDA has estimated that a ``high'' acute
consumer of olestra (every day for 12 weeks) would consume 20 g/p/d,
equivalent to eating a 2-ounce (oz) bag of potato chips every day (Ref.
11). The MRCA survey information submitted by the petitioner shows that
the 99th-percentile, 14-day average intake for olestra would be 14.8 g/
p/d (corrected to 16.3 g/p/d for caloric compensation) in the 18 to 44
year old male group. The 99th-percentile single-day intake of olestra
for the group consuming the highest level of savory snacks (13 to 17
year old male group) is 40.4 g/p/d (corrected to 45 g/p/d). It is not
likely that this high single day intake would be repeated every day in
the 12-week time frame previously mentioned.
In terms of consumption patterns, the MRCA data also show that
approximately 9 percent of lunch and dinner meals include a snack food
that could potentially contain olestra. The data also show that 63
percent of snack food eating occasions occur with a meal.
Consumption estimates of olestra-containing savory snacks were
discussed at the Olestra Working Group and FAC meetings. In particular,
CSPI raised three concerns about these estimates. First, CSPI presented
several consumption scenarios to the Olestra Working Group\6\ that the
organization
[[Page 3125]]
asserted better represented expected olestra consumption. These
consumption estimates ranged from 4.2 g/p/d to 37.5 g/p/d. CSPI's
higher consumption estimates included an increase in consumption of
olestra-containing snacks over full-fat snacks; this increase was based
on the results of a telephone survey, which survey indicated that
people think they would eat 25 percent more snacks if the snacks
contained lower fat. Based on these scenarios, CSPI asserted that there
would likely be a substantial number of snack eaters consuming olestra
in quantities similar to those fed in the 8-week human studies (8, 20,
and 32 g/d).
\6\These CSPI comments were presented by Dr. Myra Karstadt,
Ph.D. Transcript, vol. 2, p. 49. This information is also discussed
in CSPI's White Paper (Ref. 3).
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Second, CSPI asserted that consumers usually eat an entire bag of
chips at one sitting, and that bags marked ``single-serving'' typically
contain from three-quarters of an ounce to 2 ounces. Therefore, CSPI
claimed that in many cases, people would eat several ounces of chips at
one sitting, and that, in evaluating olestra's for GI effects, it is
important to consider single-sitting consumption levels.
Third, CSPI expressed concern that the MRCA survey population may
not represent the most vulnerable high-volume consumers of snack
products, such as minority teenagers resident in low socioeconomic
areas, who may both consume large quantities of savory snacks and have
poor nutritional status.
Dr. Gail Harrison, consultant to the petitioner,\7\ presented her
analysis of the MRCA survey demographics to the Olestra Working Group,
which responded to CSPI's third concern. Dr. Harrison stated that the
MRCA survey population is very representative of the U.S. population in
terms of regional census areas, census regions, and urbanization.
Further, in terms of different population groups, she said that
children of all ages are appropriately represented, while young
homemakers are slightly underrepresented. In addition, there is a
slight, though not statistically significant underrepresentation of
minority households, and the income distribution slightly
underrepresents highest-income and lowest-income households by about
three to four percent. Also, information was provided to the Olestra
Working Group by the petitioner from an analysis of USDA's 1990-1991
Continuing Survey of Food Intake that the average intake of salty
snacks (crackers, popcorn, pretzels, and corn chips) by food-stamp
recipients was about 4 g/p/d while nonrecipients consumed about 7 g/p/
d.\8\
\7\Dr. Gail Harrison, Professor, School of Public Health,
University of California-Los Angeles. Dr. Harrison presented at the
petitioner's request. Transcript, vol. 2, p. 73.
\8\Information from testimony by Mr. Thomas Breaker from the
Mathematica Policy Research Group before the Committee on
Agriculture's Subcommittee on Department Operations and Nutrition
(Transcript, vol. 2, p. 163).
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After presentations by the petitioner, CSPI, FDA, and others, the
members of the Olestra Working Group generally agreed that all issues
with regard to the chemistry and consumption of olestra had been
adequately addressed.
FDA agrees that it is appropriate to use conservative assumptions
in the safety evaluation of olestra, the effect of which is likely to
over-estimate consumption patterns. For this reason, FDA has assumed
that 100 percent of all savory snacks will be replaced by olestra-
containing snacks. That is, once olestra is approved, some consumers
will eat only savory snacks containing olestra. FDA further believes
that it is appropriate to rely on the MRCA survey data to estimate
consumption because the survey is well designed, includes a large base
of people, and a sound methodology in that the survey relies on food-
intake diaries kept by participants rather than relying on
participants' recall of what they ate sometime in the past. In light of
the discussion before the Olestra Working Group, FDA further concludes
that the MRCA survey data are sufficiently representative of the eating
habits of the U.S. population and, in particular, that the eating
patterns of low-income individuals are captured by the MRCA data and
thus, such individuals are included in the agency's consumption
estimates. In addition, FDA finds that a scenario-driven estimate of 20
g/p/d, based on consumption of 2 oz of chips per day, which is greater
than the 99th percentile, 14-day average intake in the highest
consuming group of snack eaters (18 to 44 year old makes), is a
reasonable estimate of a ``short-term'' high consumer. FDA has not used
the largest amount reported to have been eaten in one sitting during
the MRCA survey period because that amount represents an extreme that
is unlikely to be repeated for more than a few days. FDA further
concludes that there are no scientific data to justify increasing the
estimated olestra exposure derived from the MRCA survey in order to
account for the potential consumers' increase in consumption of snacks
because the snacks are low-fat.
FDA has also evaluated the potential chronic exposure to DFK's
formed from the manufacture of olestra. Mean DFK intake from olestra-
prepared snacks is 0.4 mg/p/d (DFK level of 125 ppm). The 90th
percentile for DFK's, based on an olestra intake of 7 g/p/d, is 0.87
mg/p/d. For perspective, the mean level of DFK in foods (primarily
beef, chicken, pork, and the brassica vegetables) is 9 mg/p/d and the
90th percentile background exposure (typically approximately twice
the mean for commonly consumed foods such as meat and vegetables) would
be 18 mg/p/d (Refs. 12 and 13).
Thus, FDA has determined that the available data and information
support the use of 7 g/p/d olestra as an estimate of chronic
consumption by the 90th percentile snack eater and 20 g/p/d olestra as
an estimate of shorter term consumption.
III. Toxicity Data--Discussion and Evaluation
A. Absorption, Distribution, Metabolism, and Elimination
The petitioner conducted a series of preliminary studies to assess
the absorption of olestra in rats. In order to identify which organs
might accumulate intact olestra or metabolize olestra if absorbed, rats
were intravenously (IV) injected with olestra radiolabelled with 14C on
the sucrose portion of the molecule. The radiolabelled olestra
initially deposited in the liver and, to a lesser extent, in the
spleen. The data in these early studies show that, olestra was taken up
rapidly by the reticuloendothelial system and deposited in the liver
and spleen within 3 days following intravenous injection. There was a
minor accumulation in the fatty tissues with only a trace amount
detected in expired air. At 21 days, the concentration of olestra in
the liver dropped to about 50 percent of the 3-day level. Olestra was
excreted unchanged via the biliary and fecal routes.
These results demonstrate that the olestra that accumulated in the
liver following intravenous injection was not metabolized because
radiolabel was not accumulated in other tissues, which would have
occurred if olestra had been hydrolyzed by hepatic enzymes. The absence
of olestra's metabolization was confirmed by thin-layer chromatography,
which showed intact olestra in the bile and feces. The half-life of
olestra in the liver was about 5 days.
Examination by electron microscopy of liver tissue from rats
injected intravenously with olestra showed that, at 56 days after
dosing, lipid accumulation was greatest in the Kupffer cells. By 84
days post-dosing, the greatest accumulation was in the parenchymal
cells, indicating that both kinds of cells handle olestra following
[[Page 3126]]
iv administration. Tissue deposition studies were also conducted in
rats fed one percent olestra for 30 days. Based on the data submitted,
there was no significant radioactivity detected in the liver, spleen,
lung, thymus, or adipose tissue from animals fed olestra.
Procter & Gamble conducted a series of studies in male and female
rats to determine the fate of penta-, hexa-, hepta- and octa-ester
preparations of olestra administered by gavage. The livers were removed
and lipid extracts were analyzed for the various esters. No esters were
detected by thin layer chromatography. However, the overall sensitivity
of the method was only approximately 2 to 3 percent of the administered
dose. Therefore, any olestra in rat liver extracts containing less than
3 percent of the administered olestra ester preparations could not be
detected. Additional fat balance studies conducted in the rat
demonstrated that enzymatic hydrolysis can convert mono- through penta-
ester formulations of olestra to sucrose and fatty acids while hexa-
through octa-ester formulations are not absorbed (Ref. 14).
To assess further the potential for olestra to be absorbed from the
GI tract, the petitioner conducted a series of absorption studies in
rats, guinea pigs, and mini-pigs. These studies used uniformly-labeled
olestra with high specific activity and sensitive analytical methods to
analyze tissues, especially liver, for intact olestra and urine for
14C-sucrose, a metabolic product that would result from the
metabolism of any absorbed olestra.
1. Rat Studies
In the rat studies, in order to detect the absorption of a very
small amount of the administered dose, olestra of high chemical and
radiochemical purity and high specific activity (1 millicurie/g) was
dosed at high levels (0.1 millicurie/rat). Tissues were collected,
combusted, and analyzed for radiolabelled CO2, or the lipid
fraction was extracted and analyzed for intact olestra by HPLC. Urine,
feces, expired CO2, and the carcass were analyzed for 14C.
The urine was analyzed for 14C-sucrose to assess whether olestra
had been absorbed and metabolized (Refs. 15 through 19).
Five samples which represented the extremes, and beyond, of the
olestra specification range, as well as a typical mid-range
composition, were tested. This set of samples included the following:
(1) a sample in which the fatty acid chains were 100 percent saturated;
(2) a sample in which the fatty acid chains were highly (85 percent)
unsaturated; (3) a sample rich in short-chain length fatty acids (59
percent) and penta- and hexa-esters (84 percent); (4) a sample which
represented the unheated mid-range of the olestra specification; and
(5) a mid-range olestra sample which was subjected to conditions of
repeated thermal stress as would occur in the commercial preparation of
savory snacks. Although the short-chain length fatty acids (59 percent)
and penta- and hexaesters (84 percent) sample falls outside the olestra
specifications proposed in the petition, the sample was tested to
determine the absorption of these components that might occur in
olestra in trace amounts.
The mean recovery of unabsorbed radiolabel from the rat feces, GI
tract and contents, animal wipes and animal rinse solutions, and cage
wipes and cage rinse solutions was greater than 98.5 percent of the
administered dose regardless of the radiolabeled olestra formulation
studied (Ref. 19). This recovered amount represents olestra that is not
absorbed. The recovery of absorbed radiolabel carbon from olestra
ranged from 0.02 percent of the administered dose of the high saturated
olestra formulation to 1.5 percent of the administered dose of the
short chain length and low ester formulation. The majority of the
absorbed radioactivity was found in the expired CO2 and urine. Analysis
of liver lipids for intact olestra and urine for 14C-sucrose did not
show any radiolabelled carbon. These data demonstrate that most of the
ingested olestra remains intact and is not absorbed, but is excreted
intact in the feces. The percent absorption of these olestra
formulations are shown in Table 1 below.
TABLE 1.--PERCENT ABSORPTION OF OLESTRA FORMULATIONS IN RAT ABSORPTION STUDIES
--------------------------------------------------------------------------------------------------------------------------------------------------------
Olestra Composition Percent Absorbed
--------------------------------------------------------------------------------------------------------------------------------------------------------
Low Chain/Low Ester.............................. 1.50
Mid-Range........................................ 0.16
Heated Mid-Range................................. 0.14
High Unsaturates................................. 0.05
High Saturates................................... 0.02
--------------------------------------------------------------------------------------------------------------------------------------------------------
The absorption measured for the sample rich in short-chain fatty
acids and penta and lower esters was 1.5 percent of the administered
dose. This higher value, compared to the other olestra formulations
tested, resulted from the hydrolysis of the penta and lower esters to
sucrose and free fatty acids in the GI tract. Sucrose molecules
released by hydrolysis of the lower esters in the GI tract were further
hydrolyzed by intracellular mucosal sucrase and passed into the portal
system as the monosaccharides glucose and fructose. These molecules
were metabolized normally and the radiolabel was excreted rapidly in
expired air and urine. The only variable that significantly affected
absorption was the lower chain length and lower degree of
esterification. Restriction of these lower chain length and lower
esters in olestra through specifications for the additive limits the
absorption to less than 0.16 percent of the administered dose. Of the
five radiolabelled olestra formulations studied in the rat, the heated
mid-range formulation with 0.14 percent recovery of absorbed radiolabel
represents the olestra formulation proposed to be marketed for human
consumption. FDA concludes that the low level (0.14 percent) of
absorbed radiolabelled carbon from penta- and lower esters contained in
the heated olestra is biologically insignificant because the only
components shown to be absorbed are metabolized to sucrose and fatty
acids which are metabolized normally (Ref. 19).
2. Guinea Pig Studies
The petitioner conducted studies in male and female poligeenan-fed
guinea pigs to assess the potential for increased absorption of olestra
across a damaged intestinal mucosa. (Poligeenan is known to cause
intestinal damage.) Male and female guinea pigs were given 3 percent
poligeenan in tap water, or tap water alone (controls), for 5 weeks
until GI lesions similar to those seen in acute and chronic human GI
diseases (such as ulcerative colitis and Crohn's disease) were induced.
The guinea pigs were then dosed with 200 microcuries of a heated
olestra and the absorption of
[[Page 3127]]
olestra was compared between animals with normal GI tracts and those
with compromised GI tracts.
The total recovery of radiolabelled olestra was greater than 97
percent of the administered dose for female guinea pigs in both the
normal and compromised groups.\9\ The majority of radiolabel, 87
percent to 95 percent, was found in feces and GI contents. Guinea pigs
in the compromised group had comparable amounts of radiolabel in the GI
tract and contents compared to the normal group. In addition, there
were no consistent differences between the normal and compromised
groups in the distribution of the absorbed radiolabel among various
tissues, blood, urine, or expired CO2. These findings show that
the absorption of intact olestra is no greater in guinea pigs with
compromised GI tracts than in guinea pigs with normal GI tracts (Refs.
20 and 21).
\9\Incomplete collection of fecal material from support screens,
sides and bottoms of cages, and fur of animals for male guinea pigs
resulted in lower radiolabel recovery (88.1 percent) and greater
variability in results than for female guinea pigs.
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3. Mini-Pig Studies
The absorption of a typical, mid-range heated olestra was
determined in weanling mini-pigs. The weanling mini-pig was chosen
because its GI tract is physiologically and anatomically similar to
humans and, like man, the mini-pig can tolerate a high fat diet. The
design for the mini-pig study was similar to the design in the rat
absorption studies except that expired CO2 was not collected from the
mini-pigs because metabolic cages large enough to house mini-pigs were
not available at the contract laboratory. In addition, the dose of
radiolabelled olestra was increased to 0.35 millicuries per mini-pig so
that the detection limit was comparable to that in the rat studies.
For both male and female mini-pigs, 98.9 percent of the recovered
radiolabel was found unabsorbed in the feces, GI tract plus contents,
and animal rinse solutions. No radiolabelled olestra was found in the
lipid fraction that would have contained olestra, if present, in the
lipids extracted from livers of the mini-pigs (Ref. 22).
Overall, the results from these studies in rats, guinea pigs, and
mini-pigs demonstrate that while a small percentage of the olestra
formulation consisting of penta- and lower esters is absorbed and
metabolized to fatty acids and sucrose, nearly all of the ingested
olestra remains intact and is not absorbed (Refs. 19, 21, and 22).
Heating does not significantly increase olestra absorption and
absorption is no greater when the GI tract is compromised than when it
is intact.
B. Genetic Toxicity Studies
The petitioner conducted a battery of genetic toxicity studies with
the unheated mid-range olestra formulation. Olestra was not genotoxic
in any of the following test systems: An Ames Salmonella test with or
without metabolic activation, a mouse lymphoma cell mutagenicity assay
with or without activation, an unscheduled DNA synthesis test, and a
Chinese hamster ovary cell in vitro cytogenetics test with or without
activation.
Because of solubility problems with olestra in these early genetic
toxicity studies, the petitioner conducted an additional battery of in
vitro assays and in vivo cytogenetic studies on heated mid-range
olestra with Pluronic F-68, a nontoxic, nonionic surfactant to ensure
cell contact with olestra. No evidence of mutagenicity or genetic
toxicity from heated olestra was observed in the following test
systems: The Salmonella/mammalian microsome mutagenesis assay; the
L5178Y TK +/- mouse lymphoma assay; the test for chemical induction of
unscheduled DNA synthesis in rat hepatocytes; and the cytogenicity
study in Chinese hamster ovary (CHO) cells. These tests were conducted
in the presence and absence of liver enzyme (S-9) activation at
concentrations of up to 5 mg/mL. In addition, there was no evidence of
chromosomal aberrations from heated mid-range olestra observed
following examination of the bone marrow in the in vivo cytogenicity
assays (using both acute and chronic dosing protocols) conducted on
Sprague-Dawley rats (Ref. 23). Based upon the foregoing result, FDA
concludes that olestra is not genotoxic.
C. Animal Toxicity Studies
1. Teratogenicity Studies
The teratogenic potential of olestra was evaluated in studies
conducted in the rat and rabbit. These studies establish that olestra
was not teratogenic when fed during organogenesis in either species.
Olestra was also not teratogenic nor did it affect reproduction in a
multi-generation rat reproduction/teratology study.
Olestra was fed to rats (10/group) at 3.2 percent, 6.4 percent, or
12 percent of the diet beginning on the 6th day of pregnancy. Dams were
sacrificed on days 13 and 20 of pregnancy, and the fetuses examined for
abnormalities. The uterine contents of rats killed on day 13 of
pregnancy were evaluated for implantation, resorption sites, and the
number of corpora lutea. The fetuses of the dams sacrificed on day 20
were removed and corpora lutea counted; the pups were sacrificed and
evaluated for anomalies. One-third of the fetuses were cleared and
stained for study of the skeleton, and two-thirds were sectioned for
study of the soft tissues. This study provided no evidence that olestra
is teratogenic or embryotoxic (Ref. 24).
In a rabbit teratology study, heated olestra was administered via
gavage at doses representing 1 percent, 5 percent, and 10 percent of
the diet during the critical stages of gestation (days 6 to 19);
control animals were dosed with distilled water. Dams were sacrificed
on day 30 of pregnancy and the fetuses examined for abnormalities. This
study provided no evidence that olestra was teratogenic (Ref. 25).
For the multi-generation study, weanling rats were maintained on
diets containing 0 percent, 1 percent, 5 percent, or 10 percent olestra
for a 91-day growth period. The mid- and high-dose diets were
supplemented with vitamin A (2.5 times the National Research Council
(NRC) requirements\10\) and vitamin E (five times the NRC
requirements), in order to compensate for the reduced absorption of
these nutrients in the presence of olestra. At the end of 91 days,
F0 dams were mated for a reproduction (F1A) phase and then
were mated again for a teratology (F1B ) phase. After the growth
period, the F1A offspring were mated for the F2A and F2B
generations. Olestra had no effect on mating, conception, embryonic
development, fetal and postnatal viability, or postnatal growth in
either generation (Ref. 24).
\10\NRC requirements are actually recommendations set at levels
close to the amount required for good health in the subject animals.
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2. Subchronic and Chronic Feeding Studies
Early feeding studies in rats with unheated olestra at levels of 4
percent, 8 percent, or 15 percent of the diet for 28 or 91 days
resulted in no deaths, no decrease in the absorption of triglycerides
or protein, no differences in urine or blood chemistry, hematology, or
gross or microscopic histopathology. These studies are not addressed
further.
a. Ninety-Day subchronic feeding study in rats. The petitioner
conducted two subchronic toxicity studies in rats. The first subchronic
olestra feeding study in rats showed no adverse effects but used
unheated olestra. Therefore, the petitioner, conducted a second 90-day
toxicity study in rats using olestra
[[Page 3128]]
that had been heat abused to a degree exceeding that likely to occur
during the preparation of savory snacks. Specifically, olestra that had
been heated for 7 days at 190 deg.C (representing an extreme heating
condition) was fed to 6 groups of 40 rats each (20 rats per sex) at 0
percent, 0 percent, 1 percent, 5 percent, 10 percent, and 0 percent in
rodent chow ad libitum for 90 days. Groups I and II were chow controls
while Group VI control rats were maintained on a diet that contained 10
percent previously heated triglyceride. Diets for groups II-V were
supplemented with vitamins A, D, and K (five times the NRC
requirement); vitamin E was added to these four diets at 8.0 times, 0.8
times, 4.0 times, and 8.0 times the NRC recommended levels,
respectively.
The study included twice-daily observations and weekly physical
examinations. Body weight, body weight changes, food consumption, and
olestra intake were determined weekly. Ophthalmoscopic examinations
were performed pretest and at study termination. Clinical chemistry,
hematology, and urinalysis parameters were measured at study
termination on 10 animals/sex/group.
Complete gross postmortem examinations were performed on all
animals at study termination. The brain, adrenals, ovaries, testes
(with epididymides), kidneys, and liver were removed, weighed, and
organ-to-body-weight and organ-to-brain-weight ratios were calculated.
A full complement of tissues was examined histopathologically from all
animals in Groups I, II, V, and VI surviving to study termination, and
any animals in Groups III and IV dying unscheduled deaths. Lungs,
liver, kidneys, and gross lesions were evaluated from Group III and IV
animals surviving to study termination.
Survival, physical condition, body weight, food consumption, feed
efficiency, organ weight, organ-to-body weight ratios, hematologic
parameters, and histomorphology were evaluated. Olestra fed rats
compensated for the decrease in caloric intake due to olestra having
zero calories by consuming more food than control rats. No adverse
treatment-related effects were observed. These results establish that
heated olestra is not-toxic when fed to rats at levels as high as 10
percent of their diet for a period of 90 days (Ref. 26).
b. Two-year carcinogenicity studies in rats. Two 2-year
carcinogenicity studies of olestra were conducted in rats. In the first
study, Fischer 344 rats, 70 per sex per group, were fed olestra at
levels of 0 percent, 1 percent, 5 percent, or 9 percent of the diet for
2 years with interim sacrifices at 12 and 18 months. In the second
study, Fischer 344 rats, 50 males and 73 females per group, were fed
olestra at 0 percent or 9 percent of the diet for 2 years with an
interim sacrifice at 12 months. In both studies, diets were
supplemented with five times the NRC recommended levels of vitamins A,
D, E, and K, to offset the reduced absorption of fat-soluble vitamins
in the presence of olestra. The diets in both studies also contained 2
percent fully hydrogenated palm oil to control passive oil loss (anal
leakage). The studies included twice-daily observations, and weekly
physical examinations. Body weight, body weight changes, food
consumption, and olestra intake were determined weekly for the first 12
weeks and monthly thereafter. Feed efficiency was determined during the
first 12 weeks. Ophthalmoscopic examinations were conducted pretest,
and at scheduled sacrifice. Clinical chemistry, hematology, and
urinalysis parameters were measured at 12 and 24 months. Complete gross
postmortem examinations were performed on all animals. Selected organs
were removed, weighed, and organ-to-body-weight and organ-to-brain-
weight ratios were calculated for all rats surviving to scheduled
sacrifice periods. Liver samples were taken from rats in the 9 percent
olestra groups from both studies for analysis of olestra.
Histopathological evaluations were conducted on a full complement
of tissues from animals in the control and 9 percent olestra groups
from both studies. Liver, pituitary gland, gross lesions, and tissue
masses were evaluated for all animals on study. The duodenum, jejunum,
ileum, cecum, and colon were examined for all animals sacrificed at 12,
18, and 24 months.
Rats compensated for the caloric dilution of olestra by consuming
more food than was consumed by the controls. Olestra had no effect on
ophthalmology, organ weight, organ-to-body- and organ-to-brain-weight
ratios, clinical chemistry, hematology, or urinalysis parameters. There
was no evidence that intact olestra accumulated in the liver tissue of
rats fed 9 percent olestra for 2 years.
There were no treatment-related adverse effects on growth,
longevity, or general health, and there were no treatment-related
neoplastic responses or evidence of chronic toxicity in either study.
In the first study, there were four instances in which differences
between treated groups and controls required FDA pathologists to assess
whether the effect was treatment-related: male survival, incidence of
pituitary adenoma (males and females), mononuclear cell leukemia
(males), and basophilic liver foci (females). FDA pathologists also
evaluated the following differences in incidence in the second chronic
rat study: Incidence of pituitary cysts (males), mineralization of the
renal cortex and bile duct hyperplasia, and basophilic liver foci in
females. The differences observed between treated groups and controls
in both chronic studies are marginal.
Pituitary adenomas are very common spontaneous tumors in Fischer-
344 rats with a tendency for highly variable background incidences
(Ref. 27). The increased incidence of pituitary adenoma in both sexes
in the first chronic rat study represent expected variations in
spontaneous background incidences. Thus, FDA concluded that there was
no association of the pituitary adenomas with olestra treatment.
Likewise, FDA concludes that there was no association between the
incidence of leukemia in male rats and treatment with olestra for
several reasons. First, the possible association is not supported by
the results of the second study in which there was no comparable
development of leukemia. Second, the incidences in the first study,
particularly the control group, are unusually low compared to
historical data from the National Toxicology Program (NTP) data base
and compared to the results of the second study (Ref. 27). Third,
mononuclear cell leukemia in Fischer-344 rats is a common spontaneous
disease in old age with considerable tendency for background variation
(Ref. 27). Therefore, such differences in incidence are not unusual but
rather are expected from the normal variation of spontaneous tumor
incidences.
In the first rat study, there was an increase in the number of
olestra-treated female rats with basophilic liver foci at the 1 year
interim sacrifice without any clear increase in the severity of this
lesion at the end of 2 years. However, female groups including the
terminal sacrificed animals as well as the unscheduled deaths,
demonstrated no clear increase in the incidence of basophilic liver
foci with olestra treatment. The same phenomenon of early occurrence of
basophilic liver foci in olestra-fed female rats was observed in the
second study. In both studies, the basophilic foci in the control and
treated rats were similar morphologically.
In presentations to the Olestra Working Group and the FAC, and in
its White Paper, CSPI expressed concern about the significantly higher
incidence of basophilic liver foci at the end of 12 months, although
CSPI acknowledged
[[Page 3129]]
that the difference between control and treatment groups disappeared by
24 months. CSPI asserted that, although 24 months is the majority of a
rat's lifetime, the study should have been carried out for the rats'
entire lifetime because it is possible that the foci might have
progressed to cancer. CSPI also recommended that an expert Committee
(such as NTP review) the findings.\11\
\11\Transcript, vol. 2, p. 135.
---------------------------------------------------------------------------
Based upon an examination of all of the data in both studies, FDA
pathologists concluded that these findings represented normal
biological variability in 24-month-old rats and were not related to
olestra ingestion for the following reasons. First, the findings lacked
a dose-response effect and were not observed in both male and female
rats in both chronic studies (Refs. 28 and 29). Second, the spontaneous
occurrence of basophilic liver foci is frequent and variable in aging
Fischer-344 rats (Refs. 30 and 31) and the incidence can reach 100
percent at 2 years (Refs. 32 and 33). Further, the majority of foci do
not become neoplasms. Third, the most recent studies indicate that
hepatocarcinogens induce more morphologically variable foci than those
observed spontaneously (Refs. 30, 34, and 35). Thus, the early
occurrence and morphological similarity of the basophilic liver foci in
the control and the olestra-treated female rats are not indicative of
hepatocarcinogenic potential for olestra in the rat.
Dr. John Doull, a clinical toxicologist and temporary member of the
FAC, agreed with the FDA evaluation that the basophilic liver foci
findings are not significant and that basophilic liver foci are not
predictors of carcinogenicity.\12\ Dr. Eugene McConnell,\13\ a
presenter to the Olestra Working Group, agreed with Dr. Doull, and
noted that the control groups in both chronic rat studies exhibited
abnormally low incidences of foci compared to the foci rate
historically observed in rats at these ages; he postulated that the
addition of vitamins to the feed in both chronic rat studies may have
caused this low foci occurrence rate in the control groups. The rate of
foci in the treatment groups was compared to historical control rates
and was slightly lower than historical controls.
\12\Dr. John Doull, Kansas University Medical Center Transcript
vol. 2, p. 113.
\13\Dr. Eugene McConnell, D.V.M, D.V.B.T was chief of the
Pathology Branch and Director of the Division of Toxicology Research
and Testing for the NTP. Dr. McConnell is a diplomate of the
American College of Veterinary Pathologists and the American Board
of Toxicology. Dr. McConnell consulted for the petitioner and
presented at its request. Transcript, vol. 2, p. 147.
---------------------------------------------------------------------------
Dr. McConnell also noted that the slides were reviewed by (1)
Board-certified pathologists in the contractor lab performing the study
(2) board-certified pathologists employed by the petitioner, (3) an
independent pathology laboratory,(4) a group of internationally known
pathologists, and (5) FDA pathologists. All of the reviewers came to
the same conclusion that none of the data suggests evidence of
carcinogenic activity in either species.
Therefore, in light of the discussion of the Olestra Working Group
and the presentations of CSPI and Dr. McConnell, FDA confirms its
conclusion that there was no olestra-related toxicity or
carcinogenicity in these studies.
c. Two-year chronic toxicity and carcinogenicity studies in mice.
Two 2-year mouse studies were conducted to evaluate the chronic
toxicity and carcinogenicity potential of olestra. The first mouse
study compared three levels of olestra (2.5 percent, 5.0 percent, and
10.0 percent of the daily diet) to two control groups. Olestra was
supplemented with vitamins A, D, E, and K to account for amounts which
potentially would be lost due to the high levels of olestra fed. One of
the two control groups provided basal levels of fat-soluble vitamins;
the second control group was fed supplemental vitamins A, D, E, and K.
To confirm the findings, a second mouse study was conducted with a
chow-fed control group and a 10 percent olestra group supplemented with
vitamins A, D, E, and K.
One hundred mice of each sex were placed in a total of seven groups
in the two studies. (The first mouse study had five groups and the
second mouse study had two groups.) Fifty animals/sex/group were
allocated to the carcinogenicity portions of each study, and all
survivors sacrificed at 24 months. Fifteen animals/sex/group were
allocated to the toxicity portion of each study, and all were
sacrificed at 12 months. Finally, sentinel animals (35/sex/group) were
included, and seven/sex/group were sacrificed at one, two, three, six,
and nine months for assessment of hepatic vitamin A and E status.
The studies included daily observations and weekly examinations.
Body weights and food consumption were determined weekly.
Ophthalmoscopic examinations were conducted pretest, and at scheduled
sacrifice. Clinical chemistry and hematology data, gross necropsy
observations, and organ weights were collected on animals sacrificed at
12 and 24 months in both studies. Complete gross postmortem
examinations were performed on all animals. Selected organs were
removed, weighed, and organ-to-body-weight and organ-to-brain-weight
ratios were calculated for all mice surviving to scheduled necropsy.
Histopathological evaluations were conducted on a full complement of
tissues from all control and treated animals assigned to the
carcinogenicity portion of both chronic studies.
At the end of 24 months, there were no treatment-related effects in
either study as determined by mortality, body weights, clinical
pathology, gross necropsy findings, organ weights, hematology, clinical
chemistries, or histopathology of a comprehensive collection of
tissues.
In the first study, there was an increase in the incidence of lung
carcinomas and combined lung carcinomas and adenomas in mid-dose
olestra-fed male mice but not in any other group. This association of
olestra consumption with lung tumors in male mice in the first mouse
study was not confirmed by the results of the second mouse study. Lung
adenomas and carcinomas are common lesions in Swiss CD-1 mice and tend
to have a high and variable background rate (Refs. 36 and 37). The
increased combined incidence of lung adenomas or carcinomas in male
mice in the first mouse study (Ref. 38) cannot credibly be associated
with olestra consumption, and represents expected variation in
spontaneous incidence of lung tumors in Swiss CD-1 mice (Ref. 37).
Thus, upon review, FDA pathologists concluded that this was not an
olestra-related effect because there was no other lung pathology, there
was no relation between olestra exposure and time-to-onset of the
tumors, the incidence of the tumors was typical for mice of this age
and sex based on historical data, and there was no association between
olestra exposure and lung tumors in other chronic rodent studies (Ref.
39).
At the Olestra Working Group meeting, CSPI expressed concern about
the increase in the incidence of combined lung carcinomas and adenomas
in the mid-dose male mice.\14\ Dr. Doull noted that an analysis of the
data for CSPI by Dr. Renata Kimbrough (Ref. 3) essentially agreed with
FDA's conclusions. Specifically, although the mid-dose male mice in the
first chronic study had an increased incidence in lung tumors, there
was no dose response, the increased incidence of
[[Page 3130]]
lung tumors was not repeated in the second study, and the lung tumor
incidence rate was within the range of that observed in the NTP program
in lung tumors.\15\ Dr. Doull further stated his view that this data
leads to the conclusion that olestra is not carcinogenic.\16\
\14\Transcript, vol. 2, p. 136. Discussion of this concern also
appears in the White Paper (Ref. 3)
\15\Transcript, vol. 2, p. 111.
\16\Transcript, vol. 4, p. 113.
---------------------------------------------------------------------------
Therefore, in light of the discussion before the Olestra Working
Group, FDA confirms its conclusion that the lung tumors in this study
were not an olestra-related effect.
d. Dog feeding studies. The petitioner conducted two short-term
feeding studies of olestra in beagle dogs. Olestra was fed at a level
of 4 percent of the diet for 28 days or 15 percent of the diet for 30
days. Histological examination of several tissues, including the liver,
revealed no abnormalities. The olestra-fed animals consumed more food
because of the caloric dilution of the diet by olestra, but there was
no difference in body weight gain. In a third study, olestra was fed to
dogs at 10 percent of the diet for 91 days. No adverse effects were
noted among the treated animals in terms of histopathology, hematology,
or blood chemistries.
The petitioner also conducted a 20 month chronic feeding study in
five male and five female beagle dogs. The animals were fed a chow diet
with 0 percent, 5 percent, or 10 percent olestra. Olestra diets were
supplemented by adding 1.5 times the NRC recommended dietary level of
vitamin A and 2.5 times the NRC recommended dietary level of vitamin E
to the low-dose (5 percent) diet. The high-dose (10 percent) diet
received 3.0 times the NRC recommended dietary level of vitamin A and
5.0 times the NRC recommended dietary level of vitamin E. The study
included twice-daily observations, as well as weekly physical
examinations, and determination of growth and food intake. Hematology,
clinical chemistry, serum vitamin A and E concentrations, and
ophthalmoscopic status were evaluated after 12 and 20 months of
treatment.
At the end of the study, all dogs were sacrificed and their tissues
subjected to complete gross and microscopic examination. Organ weights
and organ-to-body-weight ratios were determined for brain, adrenals,
kidney, liver, ovary, testes, and thyroid/parathyroid. A complete set
of tissues from all animals was examined by light microscopy.
No evidence of toxicity was observed, and all animals survived the
entire length of the study. Growth, as measured by body weight gain,
was not affected by olestra ingestion. Food consumption was increased
to offset the caloric dilution of the diet by olestra. No biologically
significant changes were seen in any of the hematological or
biochemical parameters measured. Histopathology revealed no olestra-
related effects (Ref. 40).
D. Toxicology Summary
In summary, the results of the toxicological tests submitted by the
petitioner support the conclusion that olestra is not toxic or
carcinogenic, not genotoxic, and not teratogenic. Heating olestra, as
would occur in the commercial preparation of savory snacks made using
olestra, does not increase the absorption of the additive or affect its
toxicity.
IV. Effect of Olestra on Absorption of Drugs
Because olestra is a fat-like material that has been shown to alter
the absorption of some lipophilic nutrients, FDA considered whether the
bioavailability of lipophilic drugs might also be affected by
consumption of olestra. To address this question, the petitioner
carried out a series of studies in both animals and humans.
The petitioner established the following criteria to use in deciding
which drugs to study:
(1)-The drugs should have wide spread use by the general population.
(2)-The absorption, metabolism and elimination of the drugs should be
similar in rats and humans.
(3)-The drugs should cover a wide range of solubilities, from water-
soluble to fat-soluble.
(4)-The drugs should include representatives of those used to prevent
life-threatening situations.
(5)-Most of the drugs should have partition coefficient data already
available.
(6)-The drugs must be commercially available in radiolabeled form.
Using these criteria, the petitioner selected the following drugs
for use in two rat studies: aspirin, diazepam, propranolol, and the
oral contraceptives ethinyl estradiol and norethindrone. Because
results of studies in rats are not definitive predictors of human
conditions (Ref. 41), the petitioner also sponsored two human clinical
trials to study the olestra/drug issue. In the first of these clinical
trials, propranolol, diazepam, norethindrone, and ethinyl estradiol
were included; in the second clinical study, the oral contraceptive Lo/
Ovral-28, containing norgestrel and ethinyl estradiol, was evaluated.
A. Effect of Olestra on the Absorption of Selected Lipophilic Drugs
(EC-40)
The primary objective of this study was to determine whether
olestra affects absorption of drugs relative to corn oil.This study was
conducted in Sprague-Dawley derived male and female rats and had three
separate experimental components. The olestra used was prepared from
safflower oil, while corn oil served as the triglyceride control.
Hydrogenated palm oil was added to both the olestra and control diets,
to mimic the earlier proposed use of olestra in combination with
convention oils.
In the first experiment, 20 male rats were fed either a control
diet with 6 percent added corn oil or a similar diet but with 6 percent
added olestra for 13 days; the test animals were then fasted, weighed,
subdivided into four groups (five rats per group), and gavaged with
slurries of either the control or olestra diets to which tritiated
diazepam or tritiated propranolol had been added. In the second and
third experiments, no initial acclimation period was used. In the
second experiment, 20 female rats were fasted, weighed, divided into
four groups (five rats per group), and gavaged with slurries of either
control or olestra diets to which tritiated ethinyl estradiol or
tritiated norethindrone had been added. In the third experiment, 10
male rats were fasted, weighed, divided into 2 groups (5 rats per
group), and gavaged with slurries of either control or olestra diets to
which C14-labeled acetylsalicylic acid (aspirin) had been added.
In all three experiments, serial blood and urine samples were taken
over a 48-hour period after dosing. Fecal samples were also collected
at 24-hour intervals. All samples collected were assayed for drug
associated radioactivity, and the results evaluated for treatment
related effects on drug absorption.
The five drugs studied in these experiments cover a range of
lipophilicity, from nonlipophilic (aspirin) to strongly lipophilic
(ethinyl estradiol and norethindrone). The petitioner concluded that
co-administration of the drugs with olestra did not affect the
absorption of any of the drugs tested when compared with corn oil.
FDA concludes that the petitioner's choice of drugs, which were
selected based on physico-chemical properties, was reasonable. Further,
the study correctly focused on rate and extent of absorption, both of
which are important factors in the overall evaluation of human drug
absorption. Although the use of total radioactivity measurements,
[[Page 3131]]
as was done in this study, is not a comprehensive evaluation taken
alone, the study design is adequate as a first exploration of olestra/
drug interactions (Ref. 41).
B. Effect of Olestra on the Absorption of Selected Lipophilic Drugs
(EC-41)
The objective of this study was to determine whether a single dose
of olestra caused an alteration of the absorption or excretion profiles
of lipophilic drugs that were orally administered prior to the olestra.
This study was conducted with Sprague-Dawley derived male rats. After a
4 day acclimation period all rats were fasted, weighed, divided into
treatment groups (four/group), and gavaged with either tritiated
diazepam, tritiated propranolol, or C14-labeled aspirin
(acetylsalicylic acid). Following each drug dosing, rats were gavaged
with one ml of either water, corn oil, or olestra. Additional rats
dosed with propranolol and aspirin received an olestra emulsion (one of
the projected final forms for initial marketing of olestra).
Serial blood and urine samples were collected over a 48-hour
period, postdosing, while fecal samples were obtained at 24-hour
intervals. Forty-eight hours after dosing all rats were sacrificed,
their gastrointestinal tracts removed and the contents collected,
selected organs excised, and carcasses frozen in liquid nitrogen and
ground. All samples were assayed for drug-associated radioactivity.
Results of the radioactivity assays were evaluated for treatment-
related effects.
The petitioner concluded that there were no differences in rate or
extent of absorption of diazepam, propranolol, or acetylsalicylic acid
when administered before olestra consumption compared with
administration prior to water consumption. Drug excretion profiles were
also not affected by olestra. Corn oil (a control substance) reduced
the rate of absorption of all drugs studied. The petitioner concludes
that these results demonstrate that olestra would not be expected to
affect the acute absorption of drugs such as diazepam, propranolol or
aspirin, and thus are consistent with EC-40. FDA concludes that, as
with EC-40, the design and conduct of this investigation are adequate
as a further exploratory study of the potential for olestra/drug
interactions (Ref. 41).
C. Effect of Olestra on Drug Bioavailability (EC-42)
The objective of this clinical trial, consisting of 3 experiments,
was to determine whether olestra consumption alters drug
bioavailability in humans when used as a substitute for absorbable
dietary fat. Subjects were assigned to test one drug in a crossover
design so that bioavailability of the drug was evaluated with single
doses of olestra, water, or a triglyceride (partially hydrogenated
soybean oil) placebo treatment. Table 2 provides basic information on
subject and treatment assignment.
TABLE 2.--SUBJECT AND TREATMENT ASSIGNMENT IN EC-42
----------------------------------------------------------------------------------------------------------------
Drug and treatment
Exp. No. Subject No. male/female Age Range (years) amount
----------------------------------------------------------------------------------------------------------------
1.................................... 5/3.................... 27 to 47............... Propranolol, 20 mg
2.................................... 4/4.................... 20 to 40............... Diazepam, 5 mg
3.................................... 0/10................... not available.......... Norethindrone, 1 mg and
Ethinyl estradiol,
0.07 mg
----------------------------------------------------------------------------------------------------------------
In each experiment, 18 g of olestra, 18 g of triglyceride, or six
ounces of water were consumed following ingestion of the respective
drug under study. Serial blood samples collected from all subjects were
processed and the resulting serums frozen for subsequent drug analyses.
The data on peak serum concentrations, times to peak, and areas under
the concentration curves (AUC) were analyzed statistically for
treatment effects.
Based on its analyses of the results from the three experiments,
the petitioner concluded that there were no statistically significant
differences in the absorption of the drugs administered with olestra,
triglyceride placebo, or water as assessed by total area under the
curve (AUC) and time to peak concentration data. The time to peak
concentration values for diazepam were slightly longer with the
triglyceride placebo than with olestra. There was wide, although not
unexpected, between-patient variability. The petitioner concluded that
a single dose of 18 g of olestra did not alter the
bioavailabilitypara.characteristics of orally administered propranolol,
diazepam, or norethindrone/ethinyl estradiol when compared to water or
a triglyceride such as partially hydrogenated soybean oil.
FDA concludes that the design of this clinical study was excellent,
and that the study may be used by itself, without any reliance on the
two studies in rats, to assess olestra's potential for affecting
absorption of lipophilic drugs. The results from EC-42 demonstrate that
olestra does not interfere with the absorption of drugs when
administered at the 18 g dose (Ref. 41).
D. Effect of Olestra on the Systemic Levels of Steroidal Hormones in
Women Taking Oral Contraceptives (EC-51)
The objective of this clinical trial was to determine the effect,
if any, of chronic olestra consumption (targeted at 20 g/d) on the
absorption and efficacy of a low-dose oral contraceptive in normal
women.
Thirty healthy, menstruating female subjects aged 20 to 38 years
were assigned to two groups. A double-blind, placebo-controlled,
crossover study design was used which covered two complete ovarian
cycles. Subjects were instructed to begin taking the oral contraceptive
Lo/Ovral-28 (0.30 mg norgestrel and 0.03 mg ethinyl estradiol), 5 days
before the onset of menstruation. One group of subjects received food
items with triglyceride placebo, while the other group received similar
food items containing a ``mid-range'' olestra formulation.
Daily intake of olestra was set at 18 g with one-third (6 g) of the
daily dose being consumed at each meal. At the conclusion of the first
28-day cycle, the treatments were crossed over (placebo to olestra,
olestra to placebo). All subjects were asked to take their oral
contraceptive only in the morning and before the morning meal. Serum
progesterone levels were determined at a baseline visit, 5 to 7 days
after menstruation and twice weekly for the remainder of the ovarian
cycles.
Serial blood samples were collected during each of the two ovarian
cycles. These samples were then processed and the serums frozen for
subsequent drug analysis. Results were evaluated for treatment effects
by comparing AUC, maximum drug concentration, and time to maximum
concentration data.
The petitioner concluded that there were no significant effects of
consuming 18 g of olestra on the absorption of either norgestrel or
ethinyl estradiol, the
[[Page 3132]]
two steroid components of Lo/Ovral-28. Serum progesterone levels in
subjects in both the olestra and triglyceride placebo groups were found
to remain in a range that would prevent ovulation, thereby providing
evidence that oral contraceptive efficacy was not affected by olestra.
The petitioner also stated that because the oral contraceptive used in
this study contains the lowest amounts of two of the most lipophilic
steroid hormones (norgestrel and ethinyl estradiol), the results from
this study should prove valid for ``all high-dose oral contraceptives
having less lipophilic constituents.'' In addition, the petitioner
believes that the data from EC-51 provide further support generally for
the conclusion from other studies in animals and humans that olestra
consumption does not alter the absorption of lipophilic drugs, and
therefore, will not affect the efficacy of orally administered drugs.
FDA believes that this study is an excellent extension from single-
dose olestra to chronic dosing, at least for the once-a-day situation.
Further, in this study, there was no evidence that olestra would affect
the efficacy of orally administered drugs (Ref. 41).
E. Summary
The petitioner has submitted two animal studies and two clinical
studies assessing olestra's potential to alter drug absorption. Procter
& Gamble believes that these studies demonstrate that olestra does not
alter the absorption nor affect the efficacy of orally administered
drugs.
Members of the Olestra Working Group were unanimous that, with
respect to drugs, all the issues had been identified and there were
sufficient data to address each issue.\17\ There was also nearly
unanimous agreement that, with respect to drug interactions, there was
no obstacle to approval and reasonable certainty of no harm from
olestra consumption.\18\
\17\Transcript, vol. 4, p. 50.
\18\Transcript, vol. 4, p. 50.
---------------------------------------------------------------------------
During the Olestra Working Group and FAC meetings and in numerous
comments to FDA, individuals have expressed concern about the effects
of olestra on coumarin drugs (e.g., Coumadin or warfarin, Dicumarol,
etc.) as well as other drugs. Dr. Ian Greaves, a specialist in
environmental and occupational medicine,\19\ expressed concern about
persons taking anticoagulants such as coumarin drugs that antagonize
Vitamin K. He asked how olestra would bind to coumarin and whether
there would be difficulty in maintaining an anticoagulant status in
people receiving coumarin who intermittently eat olestra-containing
products. He stated that his experience with managing patients on
anticoagulants is that some of them are very variable for no good
reason, and he could easily foresee a patient becoming either overly
anticoagulated or under-anticoagulated, depending on whether Vitamin K
was being bound or whether the coumarin was being bound. Also, if a
person taking coumarin happened to have an intra-cerebral bleed or
bleed from his gastrointestinal tract and was also consuming olestra,
he felt it would be difficult to know whether olestra had a role in the
bleeding. Finally, he stated he was concerned about other fat-soluble
drugs, particularly those that cross the blood-brain barrier such as
anticonvulsants, psychotropic drugs, and antidepressants. Dr. Greaves's
questions covered the concerns that were raised by other individuals.
\19\Dr. Ian Greaves is an Associate Professor and Deputy
Director, Minnesota Center for Environmental and Health Policy,
University of Minnesota School of Public Health. Dr. Greaves
presented at the request of CSPI. Transcript, vol. 2, p. 265.
---------------------------------------------------------------------------
FDA notes that the results concerning the hormonal preparations are
extremely useful because these drugs represent extremely lipophilic
substances and are substances that have a narrow therapeutic index in
which a lowering of the absorbed concentration would be a concern. In
addition, the drug, propranolol, is a compound that has very similar
physical/chemical properties to Coumadin or sodium warfarin,\20\ a drug
about which FDA has received comments concerning olestra's effects. In
response to a question by an FAC member, FDA noted that in the previous
5 years, there has been only one drug that FDA has reviewed that is
more lipophilic than the hormone drugs tested in the human drug-
interaction studies. That drug is a very specialized drug (Atovaquone),
which is an anti-pneumocystis drug used in AIDS patients.\21\
Therefore, FDA expects that the results observed in the reviewed
studies would be representative of nearly any drug on the market.
\20\Transcript, vol. p. 124.
\21\Transcript, vol. p. 124.
---------------------------------------------------------------------------
Regarding coumarin drugs specifically, FDA notes that the effects
of a variety of meals (e.g., high-protein, high-carbohydrate, and high-
fat) on absorption of sodium warfarin (Coumadin), the most commonly
prescribed form of coumarin, were studied and no effect was seen in the
total amount of sodium warfarin absorbed. Also, there was no effect on
absorption when Coumadin was consumed with high-fat or high-protein
meals. When consumed with a high-carbohydrate meal, Coumadin was more
slowly absorbed, but only for the first hour after ingestion of the
drug\22\ (Ref. 42). Therefore, FDA would not expect significant effects
on Coumadin absorption from olestra consumption.
\22\Transcript, vol. p. 119.
---------------------------------------------------------------------------
Olestra's effects on vitamin K are discussed in the Nutritional
Studies section below.
FDA concludes that the test compounds studied adequately represent
the range of physical properties of drugs marketed for human use, and
that the magnitude of olestra's effects on drug absorption were
minimal, when compared to the effects normally encountered in drug-food
interaction studies. FDA further concludes, considering the results of
all four studies, the discussions during the Olestra Working Group and
FAC meetings, comments received, and information in the literature,
that there is no evidence that consumption of olestra would
significantly influence the rate or extent of absorption of drugs
(including Coumadin drugs).
V. Nutritional Studies
A. Issues Associated with Olestra
The petitioner has hypothesized that olestra interferes with the
absorption of fat-soluble nutrients when the nutrients partition into
olestra in the GI tract. When this happens, the portion of the
nutrients that is present in the olestra phase is unavailable to the
micelle-mediated transport system and, rather than being absorbed by
the body, is excreted in the feces along with the olestra.
Neither existing olestra data nor the partitioning mechanism
suggest that water-soluble nutrients would be affected by olestra.
However, certain water-soluble nutrients such as folate and vitamin B12
(hard-to-absorb nutrients) are absorbed in multi-step processes. The
multi-step nature of the processes might allow the opportunity for
olestra to interfere with key steps in the processes, such as binding
or cleavage reactions. Calcium, zinc, and iron are limited in the U.S.
diet; thus, any effect on their absorption might increase the risk of
nutritional inadequacy. In addition, the nutrients would be present in
the diet at levels that are small, on a mass basis, relative to the
amount of olestra. Thus, if olestra has an effect on water-soluble
nutrients, these five nutrients (folate, vitamin B12, calcium,
zinc, and iron) would be the most important water-soluble nutrients
[[Page 3133]]
to monitor and the most likely to reflect adverse nutritional effects.
Therefore, folate, vitamin B12, calcium, zinc, and iron were
chosen as representative markers for olestra's effects on the
nutritional status of water-soluble nutrients.
The potential nutritional effects of olestra consumption were
studied in both humans and animals. The pig was chosen as the
appropriate animal model because it has a gastrointestinal tract
similar to that of man; it is able to ingest, tolerate, and metabolize
fat at a level comparable to that found in the human diet; and its
vitamin stores and nutritional indices are responsive to dietary
changes. Where possible, FDA has relied upon the results of human
consumption studies as the primary determinants of olestra's safety,
thereby avoiding the uncertainties raised by extrapolating from the pig
to humans. Thus, FDA is relying primarily on the human studies to
assess olestra's effects on vitamins E, D, K, and B12, and on
folate and iron. There are certain nutrients, such as vitamin A, for
which no noninvasive procedure can be used to assess status in humans.
Therefore, FDA has relied upon the results of the pig studies for
determining olestra's effects on vitamin A. In addition, there are
certain advantages to studying olestra's nutritional status in pigs.
The studies can be conducted over the major developmental and growth
periods of the pig's life, dose levels higher than those in man can be
studied, and invasive techniques can be used to measure nutrient stores
in tissues (such as bone and liver). Therefore, results from the pig
studies are valuable supportive information that expand upon the
knowledge gained in the human studies.
To apply the results of the pig studies to humans, it is necessary
to correlate the percent olestra fed in the pig diet to g/p/d olestra.
Olestra's effects on nutrients are caused by its physical presence in
the gut. If nutrients dissolve into olestra, they will be carried out
of the body with the olestra rather than being absorbed. The amount of
olestra's effect depends on the amount of olestra present in the GI
tract compared to other fats (as well as on the solubility of the
vitamins in olestra). Thus, FDA has concluded that the most appropriate
means for correlating olestra's effects in animals to humans is the
percentage by weight of olestra in the diet. For a person eating about
2,000 calories/d, 10 g of olestra would be about 2.4 percent of the
diet (Ref. 43).
B. Effects of Olestra on Fat-Soluble Vitamins-
The effect of olestra on fat-soluble vitamins was assessed in five
nutritional studies with humans and five studies with pigs, as
summarized in Table 3.
TABLE 3.--SUMMARY OF STUDIES DESIGNED TO ASSESS NUTRITIONAL EFFECTS OF OLESTRA CONSUMPTION
----------------------------------------------------------------------------------------------------------------
Human Studies Pig Studies
----------------------------------------------------------------------------------------------------------------
8-week clinical dose response (8-week DR) 26-week dose response and vitamin restoration (26-week
DR/VR)
8-week clinical vitamin restoration (8-week VR) 39-week vitamin restoration (39-week VR)
6-week vitamin D/K status in free-living subjects (6- 12-week dose response (12-week DR)
week vitamin D/K)
16-week vitamin E status in free-living subjects (16- 12-week vitamin restoration (12-week VR)
week vitamin E)
14-day vitamin A/fat absorption (14-day vitamin A/fat) 4-week dietary context (4-week DC)
----------------------------------------------------------------------------------------------------------------
In evaluating olestra's nutritional effects, FDA believes that it
is appropriate to rely primarily on the two 8-week clinical studies
because in these studies, there was complete control of nutrient
intake, they were well designed, and most nutritional parameters were
monitored. Also, these two studies were performed recently using state-
of-the-art analytical techniques and were designed taking into
consideration findings from previous studies.
FDA believes that the 16-week vitamin E study, the 6-week vitamin
D/K study, and the 14-day vitamin A/fat study are appropriately used to
support the findings in the two 8-week studies. The results of these
latter three studies do not weigh as heavily in the safety evaluation
because of their limitations: the 16-week vitamin E and 6-week vitamin
D/K studies were conducted in free-living subjects so that it was not
possible to control completely or have more than imprecise knowledge of
nutrient intake; the vitamin A/fat study investigated only olestra's
effects on preformed vitamin A absorption and provides less information
than the pig studies for assessing olestra's long-term effects on
vitamin A stores (which are derived from both preformed vitamin A and
carotenoids).
Of the studies performed in the pig, FDA believes that it is
appropriate to rely primarily on the results of the 26-week DR/VR and
39-week VR studies to assess olestra's nutritional effects because
these studies were the longest term and were designed to confirm the
results of the 12-week DR and 12-week VR studies. The 4-week DC study
was more limited in scope and duration, and was intended to demonstrate
how olestra's effects are modified by changes in dietary patterns.
1. Primary Human Studies-
The petitioner performed two 8-week human studies, in both of which
the entire diet of the subjects was controlled during the study. The
first study was the 8-week DR study which was intended to determine the
dose-response effect of olestra on the status of folate, zinc, iron,
and vitamins A, E, D, K; on the absorption of vitamin B12; and on
the bioavailability of -carotene and total carotenoids. The 8-
week VR study was intended to determine the efficacy and safety of
compensation with vitamins A, E, and D, and to confirm the conclusions
drawn in the 8-week DR study about the effects of olestra on vitamin K,
zinc, and iron status, serum 25-hydroxyvitamin D2 (25-OHD2)
concentration, carotenoid bioavailability, and vitamin B12
absorption. These two studies are of similar design and the results are
complementary.
a. Eight-week DR study design. The 8-week DR study was a parallel,
double-blind, placebo-controlled study with controlled diets fed for 8
weeks. Subjects were normal, healthy, 18 to 44 year-old males and
females. The study had four groups of 21 to 24 subjects per group (88
subjects total). Subjects were randomly assigned to treatment groups
that were balanced with respect to age, sex, body mass index (BMI),
serum -tocopherol, and total serum carotenoid concentrations.
Subjects were provided with all meals for 56 days.-
The diets were formulated to provide about 15 percent of calories
from protein, about 55 percent of calories from carbohydrate, and about
30 percent of calories from fat. The total digestible fat content was
kept the same across the four treatment groups by adding
[[Page 3134]]
triglyceride, in the form of butter, margarine, or vegetable oil, into
the diets to compensate for the amount of fat replaced by olestra in
the olestra-containing foods. Therefore, the total amount of lipid
(digestible fat plus olestra) increased with increasing olestra dose.
Olestra was added to food items (potato chips, muffins, biscuits,
and cookies) by substituting olestra for triglyceride in recipes or in
cooking oils. Because each meal contained olestra, or the corresponding
placebo (triglyceride), this study design provided maximum opportunity
for olestra to interfere with nutrient absorption.
The diets provided each subject with 80 percent to 120 percent of
the RDA of folate, zinc, and vitamins A, D, E, and K. Calcium and iron
intakes were not targeted to be within the 80 percent -120 percent RDA
range, although they were controlled and kept consistent among the
diets. Vitamin B12 levels were allowed to exceed the 80 to 120
percent RDA range in order to maintain zinc and protein consumption at
the target levels. In addition to the vitamin D in the diet, subjects
were given 20 g/day (two RDA) of vitamin D2 as a
supplement, one third of which was consumed with each meal.-
The dosages of olestra were 0 (placebo), 8, 20, and 32 g/d. Body
weights were measured every week and the subjects were questioned daily
about changes in their health, including GI symptoms. If a GI symptom
was experienced, the subject completed a detailed questionnaire that
asked about the type, severity, and duration of symptoms they
experienced. (The monitoring and reporting methods for adverse
experiences is discussed in section VI.B. of this document.) Table 4
summarizes the measurements that were made to assess the status of the
various nutrients. Most parameters were measured at baseline (week 0)
and at 2-week intervals throughout the 56-day study period.
TABLE 4.--MEASUREMENTS OF MICRONUTRIENT STATUS IN THE EIGHT WEEK DR STUDY
----------------------------------------------------------------------------------------------------------------
Nutrient Measurements
----------------------------------------------------------------------------------------------------------------
Vitamin A Serum retinol concentration\23\, serum carotenoid
concentration
Vitamin E Serum -tocopherol concentration
Vitamin D Serum concentration of 25-OHD2, 25-hydroxyvitamin D3
(25-OHD3), and 1,25-dihydroxyvitamin D (1,25-(OH)2D)
Vitamin K Serum phylloquinone concentration, urinary excretion of
-carboxy glutamic acid, plasma concentration
of des-carboxy prothrombin (PIVKA-II), plasma
prothrombin concentration, and prothrombin time, and
partial thromboplastin time
Folate Serum and red blood cell folate concentration
Vitamin B12 Schilling test, serum vitamin B12, serum vitamin B12
metabolites
Zinc Serum and urinary zinc concentrations
----------------------------------------------------------------------------------------------------------------
\23\Serum retinol concentration is the only practical measure of preformed vitamin A status that can be made in
humans who have adequate liver stores. (Other measures require invasive tissue sampling, such as measurements
of liver stores.)
b. Eight-week VR study design. The study design for the 8-week VR study
was the same as that of the 8-week DR study, except for the following
elements. The 8-week VR study had 6 groups, each containing 16 or 17
subjects (100 subjects total). The measurements of micronutrient status
in the 8-week VR study differed from those in Table 4 in that folate
and zinc were not monitored while iron status was monitored by
measuring serum ferritin and iron concentrations and total iron binding
capacity. Unlike the 8-week DR study, no vitamin D2 supplement was
consumed by the test subjects. Finally, in addition to the vitamins
provided in the diet, graded levels of vitamins A, E, and D were
provided, as described in Table 5.
TABLE 5.--VITAMIN DOSES EXPRESSED AS PER GRAM OF OLESTRA (/G) AND -PER DAY (/D) FOR THE SIX TREATMENT GROUPS IN
8-WEEK VR STUDY
----------------------------------------------------------------------------------------------------------------
Vitamin A Vitamin E Vitamin D2
-----------------------------------------------------------------------------
Treatment Group Olestra (g/d) g/ g/ g/ g/
g d mg/g mg/d g d
----------------------------------------------------------------------------------------------------------------
0 (placebo)....................... 0 0 0 0 0 0
8................................. 83 664 2.5 20 0 0
20................................ 33 660 1.5 30 0.20 4
20................................ 83 1660 2.5 50 0 0
20................................ 132 2640 3.5 70 0.80 16
32................................ 83 2656 2.5 80 0 0
----------------------------------------------------------------------------------------------------------------
c. Results and conclusions from primary human studies.--i. Vitamin
A. In the human diet, there are two sources of dietary vitamin A,
preformed vitamin A (retinyl esters) and carotenoids such as -
carotene that are converted in the body into vitamin A (provitamin A
carotenoids). Partitioning of either of these sources of vitamin A into
olestra could affect vitamin A levels in the body.
The petitioner concluded that there was no effect of olestra in
either of the two 8-week studies on the serum concentration of retinol.
This result was not unexpected because serum retinol concentrations are
relatively stable and not subject to significant change except under
conditions of prolonged and inadequate vitamin A intake. Only under
such extreme conditions would changes in liver vitamin A storage be
reflected by changes in serum retinol. Thus, the petitioner concluded,
and FDA agrees, that to establish the effect of olestra on vitamin A
status in humans, data on vitamin A liver stores collected in the pig
studies and data on the postprandial absorption of vitamin
[[Page 3135]]
A in man must be considered. Those data are discussed in sections
V.B.3.c.i. and V.B.2.c. of this document.
ii. Vitamin E. The petitioner evaluated the effect of olestra on
vitamin E status and found that there was a highly significant trend in
decreased serum levels of vitamin E with increasing olestra dose in the
8-week DR study, an effect evident by day 14 of the study. Serum
vitamin E was reduced by 6 percent, 17 percent, and 20 percent compared
to control levels when olestra was consumed at 8, 20, and 32 g/d
respectively in every meal. The maximum effect was obtained between 2
and 4 weeks.
The petitioner calculated, based on the results of the 8-week VR
study, that the effects on tissue concentrations of vitamin E were
offset by the addition of 2.07 mg of vitamin E (d--tocopheryl
acetate) per g olestra. This level is equivalent to 1.9 mg -
tocopherol equivalents/g olestra and 0.94 RDA of vitamin E per 1 oz
serving of savory snacks containing 10 g of olestra.
FDA agrees that 1.9 mg of -tocopherol equivalents/g
olestra adequately restored serum vitamin E levels in this study, as
indicated in the data adjusted for baseline serum vitamin E levels\24\
(Ref. 44). FDA finds that this study adequately controlled vitamin E
consumption, analyzed appropriately for vitamin E levels, and was of
sufficient duration to observe olestra's effect, because the effect had
reached a plateau after a few weeks into the study (Ref. 43).
Therefore, FDA agrees that compensation for olestra's effects on
vitamin E can be calculated from the results of this study, and further
agrees that 1.9 mg of -tocopherol equivalents per g of olestra
is the appropriate compensation level.
\24\In controlled diet studies such as this, the controlled diet
is often better in many respects than the free-living diet of the
subjects, thus it is not unusual that the basline vitamin E levels
were lower than controlled-diet levels. Therefore, adjustment for
baseline levels is appropriate.
---------------------------------------------------------------------------
iii. Vitamin D. In the human diet, there are two sources of vitamin
D, dietary (vitamin D2) and endogenous (vitamin D3) produced
in the body via sunlight-catalyzed dermal synthesis. The nature of the
dose-response effect of olestra on dietary vitamin D2 was
determined by measuring serum levels of 25-OHD2, which is derived
only from dietary vitamin D. Serum levels of 25-OHD3 (from
dermally synthesized vitamin D3), 1,25-(OH)2D, and 25-OHD
were also measured to assess olestra's effects on total vitamin D
status. The serum concentration of 25-OHD reflects total vitamin D
status.
The petitioner found that there was an olestra treatment effect in
the 8-week DR study on the serum concentration of 25-OHD2. At the
end of the study, the reductions in 25-OHD2 were 23 percent, 13
percent, and 27 percent for 8, 20, and 32 g olestra/d, respectively,
relative to control. The effect had levelled off within 4 weeks. There
was no effect on serum 25-OHD3 or 1,25-(OH)D. In this study, the
diet contributed 55 to 68 percent to total vitamin D status (the
remainder coming from sunlight). The amount supplied by the diet was
relatively high because of excess vitamin D2 supplied by the
dietary supplement.
Although the subjects in the 8-week VR study did not receive
supplements (the diet contributed 12 to 20 percent of total vitamin D),
the reductions in 25-OHD2 in the 8-week VR study were similar to
those observed in the 8-week DR study: 22 percent, 29 percent, and 22
percent for 8, 20, and 32 g olestra/day, respectively, relative to
control. The reductions in serum total 25-OHD were less compared to the
reductions in the 8-week DR study because a larger fraction of the
total vitamin D was endogenous. The petitioner concluded that olestra's
effect on serum vitamin D2 in the 8-week VR study could be offset
by adding 0.07 times the RDA of vitamin D2 per 1 oz serving of
savory snack containing 10 g olestra (equivalent to .07 g/g
olestra or 2.7 IU). The petitioner further concluded that olestra's
effect on vitamin D status is not nutritionally significant because the
effect is relatively small (on the order of a few percent in the 18-
week VR study) and sunlight synthesis is a more important contributor
to total vitamin D levels.
FDA agrees with the petitioner that olestra reduced serum vitamin D
in both studies. Because the effect of olestra on serum vitamin D2
levels had levelled off within the first 4 weeks of the study, FDA
considers the studies of sufficient length to assess olestra's effects
(Ref. 43). However, it is difficult to quantify olestra's effect
because of confounding factors, such as the lack of a strong
relationship between dose and reductions in 25-OHD2 in both
studies. In addition, the effect of olestra on serum total 25-OHD
levels is difficult to quantify in the 8-week VR study because total
serum 25-OHD levels were falling in the control group as well as the
treated group during the study. (For example, total serum 25-OHD levels
in the group not consuming olestra decreased 30 percent over the course
of the study.) Compensation of two of the 20 g/d olestra groups with
0.2 and 0.8 g vitamin D2/g olestra reduced the decrease
in total serum 25-OHD (which was due to both olestra and test diet
effects). At the 0.2 g/g olestra supplementation level, the
decrease in total 25-OHD was slightly less than in the group not
consuming olestra (26.8 percent vs. 30 percent respectively). With the
higher level of compensation (0.8 g/g olestra) the decrease in
25-OHD was about one-half that of the group not consuming olestra (15.6
vs. 30) (Ref. 45).
Although FDA believes that the variability of the data and the ``on
diet'' effects on vitamin D status make quantitation of the magnitude
of olestra's effects difficult, the agency concludes that the 8-week VR
study can be used to estimate olestra's effects on vitamin D because
dietary vitamin D2 consumption was not excessive and the effect of
olestra had levelled off within 4 weeks. FDA concludes that these
results show that 0.2 g vitamin D2/g olestra adequately
compensated for olestra's effects on vitamin D status in the 8-week VR
study (Ref. 45).
iv. Vitamin K. The petitioner found that in the 8-week DR study,
olestra caused a dose-response decrease in serum phylloquinone (vitamin
K1) concentration that levelled out within 2 weeks. Eight, 20, and
32 g/d olestra reduced serum phylloquinone by 36 percent, 40 percent,
and 47 percent, respectively. There was no effect of olestra on the
status of vitamin K as measured by the plasma concentration of des-
carboxylated prothrombin (PIVKA-II), urinary excretion of -
carboxyglutamic acid (urinary Gla), and plasma prothrombin
concentration, which are all measures of functional activity of vitamin
K. Prothrombin time (PT) and partial thromboplastin time (PTT), the
normal measures of clinical vitamin K status, were also not affected by
olestra intake. The 8-week VR study showed similar results. FDA agrees
with the petitioner's findings in both studies.
The petitioner concluded that the lack of any change in vitamin K
functional activity indicates that the decrease in para.serum
phylloquinone concentration does not represent a significant reduction
in vitamin K status. FDA notes that, although olestra did not
demonstrate any effect on the vitamin K-related functional parameters
(i.e., urinary excretion of -carboxy glutamic acid, plasma
concentration of des-carboxy prothrombin (PIVKA-II), plasma prothrombin
concentration, and clotting times), the length of the study was
insufficient to rule out possible effects on these vitamin K-related
functional parameters after longer term consumption of olestra. Also,
while serum levels in the studies after 56 days
[[Page 3136]]
can be considered to be only marginally reduced, when compared to true
deficiency levels, the potential remains for continued decrease with
long-term olestra consumption.
To calculate the level of vitamin K that would compensate for the
reduction of serum vitamin K levels caused by olestra consumption, the
petitioner relied upon the fact that serum vitamin K levels closely
reflect the most recent (within 24 hours) intake of vitamin K. (Vitamin
K has a half-life in serum of approximately 2 hours.) In the 8-week DR
study, a 6 day rotating menu provided different vitamin K intakes for
each day. As a result, the level of vitamin K on the days before each
biweekly blood draw varied.\25\ The serum level of vitamin K that would
result from consumption of 1 RDA (80 g) of vitamin K in the
absence of olestra was obtained from the control group measurements.
The compensation level was calculated as the amount of vitamin K needed
in the presence of olestra to maintain the serum vitamin K
concentration at the control level. This calculation yields
compensation levels of 31 g vitamin K in the 8 g/d group (4
g/g olestra), 68 g vitamin K in the 20 g/d group (3.2
g/g olestra), and 82 g vitamin K in the 32 g/d group
(2.6 g/g olestra). The petitioner averaged these three results
to yield an estimated compensation level of 3.3 g/g olestra.
\25\In the 8-week VR study a 7-day rotating menu was used to
ensure that the subjects received equivalent levels of phylloquinone
on the days prior to blood draws.
---------------------------------------------------------------------------
FDA concludes that the response of serum vitamin K to the previous
day's dietary intake is a reasonable, though imprecise, indicator of
olestra's effects on serum vitamin K levels. Thus, FDA concludes that
the petitioner's calculation provides only an estimate of appropriate
compensation levels. FDA's conclusion regarding the appropriate
compensation level for vitamin K is addressed in section V.B.4.e. of
this document.
v. Carotenoids. In the 8-week DR study, the petitioner found that
carotenoid bioavailability as measured by serum -carotene and
total carotenoid concentrations fell markedly with eight g/d olestra
consumption although higher levels of olestra consumption did not cause
a much larger decrease. At an olestra intake of 8 or 20 g/d, there was
about a 60 percent reduction in serum -carotene within the
first 4 weeks and there was essentially no further decline for the
remainder of the study. Olestra's effect on total serum carotenoids was
of a similar magnitude. These results were confirmed in the 8-week VR
study. FDA's conclusions regarding olestra's effects on carotenoids are
addressed in section V.B.4.f. of this document.
2. Other Human Studies
a. Six-week vitamin D/K study. The 6-week vitamin D/K study was a
double-blind, placebo-controlled, parallel design using 221 normal,
healthy, free-living subjects. The objective of this study was to
assess the status of vitamins D and K in subjects consuming 20 g/d
olestra. Subjects were randomly assigned to treatment groups and
balanced with respect to age, sex, and body mass index (BMI). Subjects
consumed a total of 20 g olestra or the corresponding triglyceride
placebo per day in cookies eaten at each meal. Subjects consumed self-
selected diets with an upper limit of 7 glasses of milk per day. Daily
food frequency records were used to estimate phylloquinone intake. The
diet was supplemented with 20 g (800 IU) ergocalciferol
(vitamin D2), taken in capsule form with the morning meal. The
study was conducted from February through April to lessen sunlight
effects on vitamin D status. Vitamin K status was assessed by
monitoring serum phylloquinone (vitamin K1), serum
Simplastin/Ecarin assay (S/E) (a measure of
functional prothrombin in blood), and prothrombin (PT) and partial
thromboplastin times (PTT). Vitamin D status was assessed by monitoring
serum concentrations of 25-OHD2, 25-OHD3, and 1,25-
(OH)2D. All serum parameters were measured every 2 weeks, while PT
and PTT were measured only at the beginning and end of the study.
The petitioner found that mean serum concentrations of 25-OHD2
rose in both placebo and olestra-fed groups, although serum
concentrations rose more slowly in the olestra-fed group. At week two
and beyond, the olestra group showed serum vitamin 25-OHD2 levels
that were about 19 percent below placebo, which persisted to the end of
the study. No statistically significant changes in the measurements
used to assess vitamin K status (S/E, clotting times, and serum
phylloquinone concentration) were observed in the study, except that at
week two, serum phylloquinone levels were lower in the olestra-fed
subjects. The petitioner concludes from these results that 20 g/d
olestra does not affect vitamin K status or vitamin D nutritional
status.
FDA disagrees with the petitioner's conclusions regarding olestra's
effects on vitamins D and K. First, the 19 percent decrease in serum
25-OHD2 is indicative of an olestra effect on nutritional status
and specifically, on vitamin D status. Second, the study is of limited
usefulness in assessing vitamin K status because the sensitivity of the
tests used to evaluate the impact of low serum vitamin K1 on vitamin K-
dependent clotting protein function is either poor (PT and PTT) or not
fully validated (S/E). Furthermore, the quantitative precision of the
study is diminished because the subjects were eating diets that were
not controlled. Thus, FDA disagrees with the petitioner's conclusion
that olestra does not affect vitamin D nutritional status and further
concludes that this study does not provide sufficient information for a
conclusion regarding olestra's impact on vitamin K1 nutritional
status (Ref. 46).
b. Sixteen-week vitamin E study. The 16-week vitamin E study was
also a double-blind, placebo-controlled, parallel design with 194
subjects. The purpose of the study was to assess the adequacy of 1.1 mg
of d- tocopherol acetate/g olestra in maintaining vitamin E
status in persons chronically consuming olestra and to determine the
potential effects of 18 g/d olestra on the status of vitamins K and D,
absorption of carotenoids, and concentrations of serum retinol. Test
subjects were normal, healthy, male and female free-living persons
between the ages of 18 to 65 who consumed 18 g/d olestra, with or
without 1.1 mg tocopheryl acetate/g olestra, or triglyceride placebo
for 16 weeks. The daily dose of olestra (contained in cookies and ice
cream) was to be consumed with meals; meal content was not controlled
and they were permitted to eat between meals foods of their own
choosing. Subjects were not specifically requested to evenly divide the
daily allocation of cookies and ice cream among the meals. Serum
concentrations of cholesterol, -tocopherol, -
carotene, and total carotenoids were measured biweekly. Serum 25-OHD
concentration, clotting times (PT and PTT), and serum levels of
functional prothrombin (S/E) were measured at weeks 0, 8, and 16.
The petitioner found that serum -tocopherol concentration
was reduced by 6 percent, relative to control, in the olestra group and
by 4 percent in olestra with added -tocopheryl acetate group.
Serum concentrations of -carotene and total carotenoids were
reduced by 21 to 29 percent in both olestra groups. Serum 25-OHD,
retinol concentrations, and vitamin K status were unaffected by olestra
consumption.
The petitioner concludes that 1.1 mg -tocopheryl acetate/g
olestra was not sufficient to compensate for olestra's effect in this
study and that olestra did
[[Page 3137]]
not affect vitamin D or K status. FDA agrees that compensation for
olestra's reduction of vitamin E status was not adequate and that there
was no evidence of an olestra effect on vitamin D and K status in this
study. However, the value of this study is limited because the subjects
were free-living, which limits the quantitative precision of the study
in predicting olestra's nutritional effects (Ref. 47).
c. Vitamin A/fat study. The vitamin A/fat absorption study was a
parallel, double-blind, placebo-controlled study of 70 healthy males.
The subjects consumed 0 or 10 g/d olestra in potato chips for a 30-day,
free-living adaptation period. The adaptation period was followed by a
14-day in-house period in which the subjects received 0, 8, 20, or 32
g/d olestra in potato chips and cookies. One-third of this daily dose
was eaten with each meal except on the days when vitamin A and fat
absorption was measured; on those days, the entire dose of olestra was
consumed in potato chips at breakfast along with the radiolabeled
marker. The dose response of olestra on the absorption of preformed
vitamin A was measured using radiolabeled retinyl palmitate.
The petitioner evaluated the results of the vitamin A aspects of
this study and concluded that neither 8 nor 20 g of olestra in a single
meal had any effect on the absorption of 3H-labeled retinyl palmitate
contained in the meal, and further that 32 g of olestra in the test
meal reduced vitamin A absorption from that meal by 19 percent relative
to controls. The petitioner also calculated that when high responders
(the group of subjects showing high triglyceride levels after fat
ingestion) were removed from the calculation, olestra's effect on
vitamin A absorption was reduced to 13 percent.
FDA finds no justification for removing a part of the subject
population from the calculation and thus believes that the 13 percent
reduction figure is of no value in assessing olestra's effects on
vitamin A. FDA agrees, however, that the study supports the conclusion
that olestra induced a 19 percent reduction, and considers this amount
to be the most accurate measurement of olestra's effect on preformed
vitamin A absorption in this study (Ref. 48).
The petitioner concluded that the lack of an effect at the lower
olestra doses (8 and 20 g) indicates that chronic consumption of
olestra at the 90th percentile estimated intake by the total population
(7 g/d) or the 90th percentile estimated acute intake for the heaviest
consumers of savory snacks (18 to 44 year old males, 20 g/d\26\) will
have no effect on preformed vitamin A absorption. While this
interpretation of the data appears to be reasonable, FDA notes that
this study only addresses olestra's effects on preformed vitamin A
absorption. The study cannot, by design, address the decrease in
vitamin A stores that would be caused by olestra's effects on
carotenoid absorption.
\26\A dose of 20 g is equivalent to the consumption of two 1-oz
servings of savory snacks at a single meal.
---------------------------------------------------------------------------
3. Pig Studies
The petitioner conducted five nutritional studies of varying
lengths (12, 12, 26, 39, and 4 weeks) in pigs. The objective of the 12-
week DR study was to confirm the hypothesized dose-response effect of
olestra on fat-soluble vitamins A, D, E, and K, and to determine
whether there were any effects on specific marker nutrients that are
difficult to absorb or are limited in the American diet (folate,
vitamin B12, calcium, iron, and zinc). The purpose of the 12-week
VR study was to determine whether the effects of olestra on the status
of vitamins A and E that were observed in the 12-week DR study could
adequately be compensated for by the addition of vitamins to the diet.
The 26-week DR/VR and the 39-week VR studies were undertaken after
the 12-week studies to evaluate olestra's effects on nutrient status in
the period beyond the maximum growth phase. The purpose of the 26-week
DR/VR study was three-fold: (1) To confirm the dose-response effect of
olestra observed in the 12-week DR study; (2) to evaluate the effect of
olestra on fat-soluble vitamins, folate, vitamin B12, calcium,
zinc, and iron, with longer exposure times and lower olestra levels
than had been tested in the 12-week DR study; and (3) to determine the
amounts of fat-soluble vitamins that would need to be added to the diet
to compensate for olestra's effects. The 39-week VR study was designed
to evaluate over a longer exposure period the effects of 0.25 percent
olestra and added vitamins A and E that were measured in the 26-week
DR/VR study. The 4-week DC study was designed to determine whether
olestra's effects on vitamins A and E were dependent on the timing of
olestra consumption (with meals or temporally separated from meals) or
the means by which olestra enters the diet (as chips or admixed with
feed).
a. Study design of 12-, 26-, and 39-week studies. The 12-week DR,
12-week VR, 26-week DR/VR, and 39-week VR pig studies used similar
materials and methods. The 12-week DR study is described in depth. For
the three other pig studies, only the differences from the 12-week DR
study are described.
i. Twelve-week DR study. The test animals were a domestic, cross-
bred strain of pigs, and were 5 to 7 weeks of age when received. All
treatment groups contained equal proportions of females and castrated
males. The pigs were acclimated for 14 to 16 days before being placed
on experimental diets: During the first 7 to 9 days of the acclimation
period, the animals were fed a 20 percent protein swine chow
(University of Wisconsin-Madison) ad libitum; during the last 7 days
they were fed the purified basal diet that was fed throughout the
remainder of the study.
The basal diet was a purified diet consisting of about 25 percent
casein, 24 percent starch, 24 percent sucrose, 5 percent Alphacel, 14
percent lard, and 8 percent of a vitamin/mineral premix. The diet
delivered about 30 percent of calories from fat, a level equivalent to
the target fat consumption level recommended for the U. S. population,
but lower than current actual fat consumption. The ratio of calories
from saturated:monounsaturated:polyunsaturated fats was targeted at
1:1:1.
The basal diet provided the National Research Council (NRC)
requirements of micronutrients for 5 to 10 kilogram (kg) pigs. The NRC
requirements, as a percentage of the feed, decline for many nutrients
as a function of increasing body weight. Therefore, as the pigs grew,
most nutrients were actually fed in excess of the body-weight-specific
NRC requirements.
In the basal diet, vitamin A was provided as a 3:1 ratio of retinol
equivalents from retinyl palmitate and -carotene,
respectively. This targeted ratio simulated the average dietary sources
of vitamin A for the U. S. population. Vitamin E was provided in the
form of d,l--tocopheryl acetate. Dietary vitamin D was
supplied as ergocalciferol (vitamin D2). In addition to dietary
vitamin D, pigs in this study were exposed to 2 minutes of ultraviolet
(UV) light each day. Vitamin K was provided as phylloquinone, the major
source of vitamin K in the human diet, rather than as menadione, the
form typically added to swine chow.\27\ Folate was provided as folic
acid, vitamin B12 was provided as cyanocobalamin, calcium as a
mixture of CaHPO42H2O
[[Page 3138]]
and CaCO3, iron as FeSO47H2O, and zinc as
ZnSO47H2O. The micronutrients were added directly to the diet,
separate from the olestra, during diet preparation.
\27\The swine NRC nutrient requirement table gives the vitamin K
requirement as menadione; there is no value listed for
phylloquinone. Therefore, the petitioner calculated the added amount
of phylloquinone based on the assumption that phylloquinone is
equivalent to menadione on a weight basis.
---------------------------------------------------------------------------
The 12-week DR study consisted of 7 groups of pigs, containing 12
pigs each (except the control group of 20 pigs). Olestra was added to
the diets at levels of 0 percent (control), 1.1 percent, 2.2 percent,
3.3 percent, 4.4 percent, 5.5 percent, and 7.7 percent (by weight). The
olestra was heated before incorporating into the diet by frying potato
chips.
Growth, feed intake, hematology, and clinical chemistry measures
and the status of vitamins A, B12, D, E, and K, and folate, calcium,
zinc, and iron were measured at regular intervals. Stores of vitamins
A, E, B12, calcium, phosphorus, zinc, and iron were measured in the
liver or bone at the termination of the study. The measurements used to
assess the status of the various nutrients are summarized in Table 6.
TABLE 6.--MEASUREMENTS OF NUTRIENT STATUS IN THE 12-WEEK DR PIG STUDY
----------------------------------------------------------------------------------------------------------------
Nutrient Measurements
----------------------------------------------------------------------------------------------------------------
Vitamin A Liver and serum concentration
Vitamin E Liver, serum, and adipose tissue concentration
Vitamin D Serum concentration of 25-OHD2, 25-OHD3, and 1,25-
(OH)2D
Vitamin K Prothrombin time
Folate Plasma concentration
Vitamin B12 Liver concentration
Calcium Bone, serum calcium, and bone ash concentration
Phosphorus Bone and serum concentration
Iron Liver iron concentration and serum concentrations of
hemoglobin, hematocrit, mean corpuscular volume (MCV),
mean corpuscular hemoglobin (MCH), and mean
corpuscular hemoglobin concentration (MCHC)
Zinc Liver, bone, and serum concentration
----------------------------------------------------------------------------------------------------------------
ii. Twelve-week VR study. The 12-week VR study consisted of 11
groups of pigs (one baseline, one control, and nine treatment groups),
each containing 10 pigs (5 castrated males and 5 females). Pigs were
exposed to 2 minutes of UV light each day. The amount of olestra and
total amounts of vitamins A, D, and E targeted to be in the diet for
the nine treatment groups is summarized in Table 7.
[[Page 3139]]
TABLE 7.--STUDY DESIGN FOR 12-WEEK VR PIG STUDY
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Percent Olestra Vitamin A (x NRC)\1\ Vitamin D (x NRC)1 Vitamin E (x NRC)1
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
0 (control)....................... 1.00 1.00 1.00
1.1............................... 1.05 1.20 1.20
1.1............................... 1.35 1.80 1.90
1.1............................... 1.65 2.40 2.60
4.4............................... 1.65 2.40 2.60
4.4............................... 2.40 4.20 4.60
4.4............................... 3.15 6.00 6.60
7.7............................... 2.05 3.80 4.15
7.7............................... 3.45 6.60 7.30
7.7............................... 4.85 9.40 10.45
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\1\Expressed as multiples of the NRC requirements of pigs.
[[Page 3140]]
A premix was prepared to provide additional amounts of vitamin A as
well as vitamin D for each level of olestra fed. Vitamin D was added as
vitamin D2 (ergocalciferol), while vitamin A was in the form of
retinyl palmitate. Above-basal levels of vitamin E, in the form of d-
-tocopheryl acetate, were combined with the olestra instead of
adding it directly to the diet because this procedure mimics that which
would be used to add vitamin E to olestra for savory snack use, i.e.,
the vitamin would be added directly to the frying oil.-
iii. Twenty-six week DR/VR study. The 26-week DR/VR study had 11
groups, each containing 10 pigs (5 castrated males and 5 females).
Olestra was fed at five levels (0.25, 0.5, 1.1, 3.3, and 5.5 percent).
Seven of the groups (baseline, control, 0.25, 0.5, 1.1, 3.3, and 5.5
percent olestra) did not have any additional vitamins above those
present in the basal diet. The other four groups consumed added
vitamins as described in Table 8.
TABLE 8.--VITAMIN DOSES FOR THE FOUR TREATMENT GROUPS IN THE 26-WEEK DR/
VR PIG STUDY THAT HAD VITAMIN COMPENSATION
------------------------------------------------------------------------
Vitamin E (mg d--
Percent Vitamin A (IU/kg diet) tocopherol acetate/g
olestra olestra)
------------------------------------------------------------------------
5.5 3,300 1.71
0.25 150 1.71
0.25 300 3.42
0.25 600 5.13
------------------------------------------------------------------------
Additional vitamins were added in the same manner as described for
the 12-week VR study. The pigs in the vitamin-compensated 5.5 percent
olestra group were exposed to 2 minutes of UV light each day. UV
exposure was eliminated in the remainder of the groups in order to
eliminate the possibility that the UV light might affect the magnitude
of olestra's effect on dietary vitamin D2. Instead, the diet was
modified by increasing the vitamin D level to two times the NRC
requirement to produce more readily measurable levels of vitamin
D2 in the serum.
In addition to the measurements of nutrient status listed in Table
6, serum parathyroid hormone (PTH) was monitored.
iv. Thirty-nine week VR study. The 39-week VR study consisted of
the following four groups of 10 pigs each (5 castrated males and 5
females): baseline, control, 0.25 percent olestra, and 0.25 percent
olestra with 150 IU vitamin A/kg diet (60 IU/g olestra) and 1.71 mg d-
-tocopherol acetate/g olestra. There was no UV exposure in
this study and the diet was modified by increasing the vitamin D level
to two times the NRC requirement to produce more readily measurable
levels of vitamin D2 in the serum. In addition, vitamin K level in
the basal diet was lowered to one-fifth the level that was fed in the
other three studies.
In addition to the measurements of nutrient status listed in Table
6, serum parathyroid hormone (PTH) was monitored.
b. Study design of the 4-week DC study. Young pigs, 7 to 9 weeks of
age at the start of the study were fed a casein-based diet formulated
to contain at least one times the NRC requirements of micronutrients.
Five groups of 10 pigs each were fed 0 percent or 2.2 percent olestra
for 4 weeks. A sixth group of 10 pigs provided baseline data for
vitamin A, D, and E tissue concentrations. The olestra was fed either
admixed in the diet, as chips prior to each meal, as chips prior to the
noon meal only, or as chips fed between the noon and evening meal.
The petitioner evaluated the change in status of vitamins A, D, and
E at the end of the 4-week study through serum measurements of the
concentrations of vitamin A (retinol), vitamin E (-
tocopherol), and vitamin D (25-hydroxyvitamin D2 and 25-
hydroxyvitamin D3) and liver measurements of vitamin A (total
retinol and retinyl esters) and vitamin E (-tocopherol).
c. Results and conclusions from pig studies. The results of the 4-
week DC study will be discussed in section V.B.4.a. of this document.
i. Vitamin A. Data on the dose-response effect of olestra on liver
vitamin A stores were collected in the 12-week DR study and the 26-week
DR/VR study. The petitioner observed that olestra caused a nonlinear
dose-response reduction in hepatic vitamin A stores, in which lower
amounts of olestra had a greater proportional effect on stores, in both
the 12-week DR and 26-week DR/VR studies. In the 26-week DR/VR study,
the decreases in liver vitamin A (relative to controls) were 45 percent
(0.25 percent olestra), 57 percent (0.5 percent olestra), 65 percent
(1.1 percent olestra), and 88 percent (3.3 percent and 5.5 percent
olestra). The reductions observed in the 12-week DR study were very
similar, with the highest olestra intake (7.7 percent) causing a
greater than 90 percent decrease. Serum vitamin A levels also decreased
in a dose-response manner with increasing olestra intake in both
studies.\28\
\28\Unlike adult pigs, weanling pigs do not have large stores of
vitamin A so liver stores are not able to compensate for olestra's
interference with absorption of vitamin A; thus the effect on
vitamin A status is also manifest in the serum levels.
---------------------------------------------------------------------------
In both the 12-week VR and the 26-week DR/VR studies, the addition
of varying levels of vitamin A to the diet resulted in a linear
increase in liver vitamin A stores. For the 12-week VR study, the
petitioner calculated that the effect of olestra on liver vitamin A
stores could be offset by adding 58.1 IU of vitamin A/g olestra in the
diet. FDA calculates the appropriate compensation level separately for
each level of olestra in the diet, because the required compensation
level in IU/g changed as a function of dietary olestra level, and
determined that the compensation level ranged from 130.8 IU vitamin A/g
olestra at 0.1 percent olestra to 45.8 IU vitamin A/g olestra at 7.7
percent olestra (Ref. 49).
For the 26-week DR/VR study, the petitioner calculated that 170 IU
vitamin A/g of olestra compensates for olestra's effects on vitamin A
liver status, which is equivalent to 93 g retinyl palmitate/g
olestra, or 0.34 RDA of vitamin A per 1-oz serving of snacks containing
10 g olestra. FDA agrees that this calculation is appropriate and that
when olestra is present at 0.25 percent of the pig diet, approximately
170 IU of retinol/g olestra maintains the liver vitamin A levels at
control values\29\ (Ref. 49). One hundred and seventy IU of retinol/g
olestra is equivalent to 51 retinol equivalents/g olestra.
\29\The estimates from the 12-week study are somewhat smaller
than estimates obtained from the 26-week pig study; in the 12-week
study, the required supplementation level for 0.25 percent olestra
was 128 IU/g olestra.
---------------------------------------------------------------------------
The petitioner concluded and FDA agrees that the results of the 39-
week VR
[[Page 3141]]
study confirm olestra's effect on vitamin A liver stores, although FDA
notes that the amount of vitamin A added to the diet in the 39-week
study (60 IU vitamin A/g olestra) was not sufficient to compensate for
olestra's effect on vitamin A.
ii. Vitamin E. In the 26-week DR/VR study, the decreases in liver
vitamin E (relative to controls) were 24 percent for 0.25 percent
olestra, 31 percent for 0.5 percent olestra, 53 percent for 1.1 percent
olestra, 71 percent for 3.3 percent olestra, and 75 percent for 5.5
percent olestra. In the 12-week DR study, the reductions were slightly
larger (e.g., 60 percent for 1.1 percent olestra, 69 percent for 2.2
percent olestra, 75 percent for 3.3 percent olestra, 78 percent for 4.4
percent olestra, 80 percent for 5.5 percent olestra, and 81 percent for
7.7 percent olestra). Vitamin E concentration in adipose tissue showed
a slightly smaller decrease in both studies; for example, with 5.5
percent olestra, adipose vitamin E concentration had fallen by about 73
percent in both the 12-week DR and 26-week DR/VR studies.
The results of the 12-week DR and 26-week DR/VR studies showed that
effects of olestra on vitamin E status were similar in the serum and
liver, although the percent decrease in vitamin E was slightly larger
for liver than for serum. The petitioner concluded, and FDA concurs,
that this relationship confirms that serum vitamin E concentration is a
reliable measure of vitamin E status. The concentration of vitamin E in
adipose tissue also changed in a similar fashion to the changes in
serum and liver concentrations although the magnitude and rate of
change were not as great.
The petitioner concludes that 2.09 IU of vitamin E/g olestra offset
olestra's effects in the 12-week VR study; in the 26-week DR/VR study
(where olestra was fed at a lower level), 2.79 IU of vitamin E/g
olestra (which translates to 2.06 mg d--tocopheryl acetate/g
olestra) offset olestra's effects. FDA concurs with the petitioner's
general conclusions and with the calculated level of 2.79 IU vitamin E/
g olestra from liver measurements in the 26-week VR/DR study. FDA's
calculated compensation levels for the other studies, as shown in Table
9, differ slightly because of small differences in the choices of
variables to fit the curves in the statistical analyses (Refs. 50 and
51).
[[Page 3142]]
TABLE 9.--FDA-CALCULATED COMPENSATION LEVELS OF VITAMIN E TO RESTORE LIVER AND SERUM LEVELS BASED ON 12-WEEK VR AND 26-WEEK DR/VR STUDIES
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Vitamin E compensation (IU/g olestra)
Study Olestra level (%) -------------------------------------------------------------------------------------------------------------------
Liver compensation level Serum compensation level
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
26-week DR/VR 0.25 2.79 2.98
12-week VR 1.1 2.66 2.76
12-week VR 4.4 2.27 2.34
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
[[Page 3143]]
iii. Vitamin D.--a. Petitioner conclusions. The petitioner
concluded that the 12-week DR study established a dose-response effect
for olestra on dietary vitamin D at olestra levels up to 4.4 percent of
the diet, as measured by serum concentration of 25-OHD2; the serum
concentration of 25-OHD2 was about 10 percent less than control in
the 1.1 percent olestra group and about 35 percent less than control in
the 2.2 percent, 3.3 percent, and 4.4 percent groups. At higher olestra
levels, changes in the dietary contribution to total circulating 25-OHD
were confounded by changes in the contribution from vitamin D3
synthesized in the skin.
The petitioner also concluded that in the 12-week VR study, serum
concentration of 25-OHD2 increased in a dose-response manner as
the amount of vitamin D2 added to the basal diet was increased, at
all levels of olestra. However, interpretation of the serum 25-
OHD2 data at the mid- and high-olestra levels (4.4 and 7.7
percent) was confounded because the proportion of 25-OHD3 in the
serum decreased with increasing levels of olestra at these treatment
levels. The petitioner has suggested, that this decrease in serum 25-
OHD3 may have resulted from the effect of the high levels of
olestra on the reabsorption of biliary vitamin D3. Reduced
reabsorption of biliary vitamin D3 would tend to increase the
serum concentration of 25-OHD2 because of diminished vitamin
D3 competition for the liver 25- hydroxylase.
Using the serum 25-OHD2 concentrations from the groups fed 1.1
percent olestra in the 12-week VR study, the petitioner calculated that
the amount of vitamin D required to restore serum 25-OHD2 to the
control level was 13.0 IU vitamin D/g olestra, which is equivalent to
0.33 RDA/1 oz serving of chips containing 10 g olestra. The petitioner
considers that the confounding effect of vitamin D3 was absent or
minimal when olestra was fed at 1.1 percent of the diet.
The petitioner concluded that in the 26-week DR/VR study, 5.5
percent olestra (no extra vitamins) reduced plasma 25-OHD2 by 20
percent at week 26. At week 16, serum 25-OHD2 levels in the 3.3
percent and 5.5 percent olestra groups were significantly lower than
controls by 23 percent and 35 percent, respectively.
The petitioner concluded that in the 39-week VR study, olestra
decreased serum levels of 25-OHD2 by the same magnitude as in the
26-week DR/VR study, while serum 25-OHD3, total serum 25-OHD, and
serum 1,25-(OH)2D were not affected. Serum 25-OHD2 levels
were 13 to 15 percent lower than week 12 and week 26. At week 39, the
values were 6 to 11 percent lower than controls, but this difference
was not statistically significant.
b. FDA conclusions. FDA concludes that the results of the pig
studies are of limited utility for quantifying olestra's effects on
vitamin D, for several reasons. First, FDA notes that vitamin D levels
were never measured in the diet as fed in any of the pig studies. This
lack of measurement leaves open the possibility that addition or mixing
errors might have occurred, affecting the vitamin D levels in the feed.
Second, the confounding effect of UV exposure in several of the studies
makes interpretation of the results difficult.
The 26-week DR/VR study was designed to prevent UV light exposure
to any group except the 5.5 percent olestra/low vitamin group where 2
minutes of exposure were to be provided per day. However, an accidental
UV light exposure (not more than 13 hours) to this group on day 23 of
the study likely caused the very high 25-OHD3 levels and very low
25-OHD2 levels observed at week 4. In addition to the accidental
exposure of the 5.5 percent olestra/low vitamin group to UV light, it
appears that at least 10 other animals may have been exposed to UV
light in at least the 12th week of the study, as evidenced by their
elevated serum 25-OHD3 levels. Because a definitive cause for
these elevated serum 25-OHD3 values could not be determined, FDA
considers the vitamin D data from the 26-week DR/VR study to be
confounded (Ref. 52).
Although pigs in the 39-week study were not exposed to UV light,
pigs consumed only one level of olestra, therefore no dose-response
information was obtained.
FDA agrees with the petitioner that in the 12-week VR study, serum
concentration of 25-OHD2 increased in a dose-response manner as
the amount of vitamin D2 added to the basal diet was increased, at
all levels of olestra. FDA further agrees with the petitioner that the
decrease in serum 25-OHD3 observed in the mid- and high-level
groups may have resulted from olestra's effects on the reabsorption of
biliary vitamin D3. However, FDA also believes that the serum 25-
OHD2 levels may have been confounded by the daily 2-minute
exposure to UV light, which caused an increase in serum levels of 25-
OHD3 in both 12-week studies. Therefore, FDA concludes that the
results from the mid- and high-dose groups in the 12-week VR study
cannot be used to determine a quantitative compensation value for
vitamin D2 because of the apparent interaction between serum 25-
OHD3 and 25-OHD2 levels.
FDA believes that the most useful data from the pig studies comes
from a comparison of the control and 1.1 percent olestra groups in the
12-week VR study. Accordingly, FDA believes that the petitioner's
calculation based on the 12-week VR study that 13 IU vitamin D/g
olestra will compensate for olestra's effects in pigs exposed to daily
UV light may be an approximation of appropriate supplementation level
for vitamin D. However, the agency believes that it cannot rely on the
12-week VR data by themselves to establish a compensation value for
vitamin D2, because of the possible confounding effects of UV
exposure and the lack of measurements of vitamin D levels in the diets
as fed (Refs. 53 and 54).
iv. Vitamin K. There were no statistically significant effects of
olestra on prothrombin time in any of the pig studies. The petitioner
concluded, therefore, that olestra does not affect vitamin K status.
Although FDA agrees that prothrombin time was not affected by olestra
consumption, the agency does not believe that these results are
adequate to determine the potential effects of olestra on vitamin K
status, because, as discussed below, prothrombin time is not a
sufficiently sensitive analytical method and the diets of the test
animals appear to have been overfortified with vitamin K.
Prothrombin time is an insensitive indicator of vitamin K status.
The petitioner agrees that there are more sensitive indicators of
vitamin K status such as direct measurements of clotting factors in
blood, urinary excretion of -carboxyglutamic acid, and plasma
levels of des-carboxylated or under-carboxylated vitamin K-dependent
proteins (the PIVKA-II assay). The petitioner states however, that
these methods were not used because they had not been used previously
or validated in the pig and no body of historical data exists.
Nevertheless, FDA believes that use of an insensitive indicator limits
the conclusions that can be drawn from these pig studies regarding
vitamin K status.
FDA believes that the usefulness of the data from the 12-week and
26-week DR/VR studies is further limited because test animal diets were
oversupplemented with vitamin K. Because vitamin K is a highly
lipophilic fat-soluble vitamin, FDA considers it reasonable to assume
that it will partition into the olestra in the GI tract, in the same
manner as the other fat-soluble vitamins. Thus, oversupplementation is
significant
[[Page 3144]]
because it could mask any effect of olestra on vitamin K status.
FDA believes the pig diets were oversupplemented with vitamin K in
the 12-week and 26-week DR/VR studies for two reasons. First, the NRC
requirement for vitamin K in swine is in terms of amounts of menadione,
not phylloquinone (the form of vitamin K fed to the pigs). The NRC
requirement for menadione, 500 g/kg, is in a corn-soybean meal
base and this likely exceeds the requirements needed for a casein-based
semisynthetic diet that should not contain any substance that might
inhibit vitamin K metabolism. Second, FDA disagrees with the
petitioner's assumption that phylloquinone is necessarily of equal
potency on a weight basis as menadione. Unlike phylloquinone, menadione
is biologically inactive and must be alkylated in the liver to
menaquinone to become biologically active. Phylloquinone, following
intracardiac administration, was 10 times more active than menadione on
a weight basis at restoring the prothrombin response in rats that were
partially depleted of vitamin K (Ref. 55). Therefore, FDA cannot rule
out the possibility that phylloquinone is a more potent source of
vitamin K on a weight basis than menadione in swine following oral
administration, which would lead to further oversupplementation (Ref.
56).
4. Overall Conclusions Regarding Olestra's Effects on Fat-Soluble
Vitamins-
a. Consumption scenarios. The petitioner has asserted that in the
8-week human studies and in all of the pig studies (except the 4-week
DC study), olestra's effects on fat-soluble nutrients are exaggerated
because the additive was always consumed with meals. In addition, in
the pig studies, olestra was admixed with all the feed, rather than
being present in only select dietary ingredients (such as chips). The
petitioner hypothesizes that if olestra is eaten in a snack between
meals (instead of being eaten with a meal), there will be fewer
nutrients available with which it can interact, and that olestra's
effects on nutrients would be expected to be greatest when olestra and
the nutrients are intimately intermixed in the GI tract at the same
time.
The petitioner has provided results of consumption surveys showing
that in the United States, at the estimated 90th percentile consumption
level, savory snacks are eaten only four times per week, and one-third
of those occasions are between meals. With this consumption pattern,
olestra savory snacks will be eaten 32 times in an 8-week period (as
compared to 168 meals during that time), and 20 of those times will be
with meals. (In other words, during the 8-week period, 148 meals (or 88
percent) will be consumed without a savory snack.) These data mean
that, although a majority of snacks are eaten with meals, because of
the infrequency of snack consumption, a majority of nutrient intake
will occur in the absence of olestra savory snacks. In contrast, in
both 8-week studies, olestra was eaten 165 times in 8 weeks with every
meal, which means that essentially all of the nutrient intake occurred
with olestra consumption.
The petitioner presented the following examples of the consequences
of consumption patterns on olestra's effects on nutrients. First, the
petitioner calculated the expected effect of olestra on -
carotene in consumers eating snacks with the eating patterns reported
in the MRCA survey data.\30\ In the first scenario, the petitioner
assumed that absorption of -carotene eaten with olestra would
be decreased by 60 percent and absorption of -carotene eaten
at all other times would not be affected. In a second scenario,
presented at the Olestra Working Group and FAC meetings,\31\ the
petitioner assumed that absorption of -carotene eaten with
olestra would be decreased by 60 percent, absorption of -
carotene eaten at eating occasions either before or after the olestra
eating occasion would be decreased by 30 percent, and absorption of
-carotene eaten at all remaining times would not be affected.
Using these assumptions the petitioner calculated that an average snack
consumer would have a decrease in serum -carotene levels of
5.6 percent in the first scenario and about 6.8 percent in the second
scenario. For the heaviest consumers (top 10 percent), the first
scenario would result in a decrease in serum levels of about 10
percent, while the second scenario would result in decreases of 13 to
14 percent.
\30\ Transcript, vol. 1, p. 84 and vol. 3, p. 234.
\31\Transcript, vol. 3, p. 234.
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The petitioner further asserts that the 4-week DC study in pigs and
16-week vitamin E study provide evidence that olestra's effects on fat-
soluble nutrients measured in the pig studies and in the 8-week human
studies exaggerate the effects expected with a normal savory snack
consumption pattern. This effect is confirmed by a comparison of the 8-
week DR study (where olestra and the vitamins were always consumed
concurrently) with results of the 16-week vitamin E study (in which
free-living subjects consumed olestra throughout the day but not
necessarily concurrently with the consumption of all vitamin E or
carotenoids). In the 8-week DR study, the effects on vitamin E status
and serum -carotene concentration measured in the 20 g/d
olestra group are about three-fold greater than those measured in the
free-living subjects in the 16-week vitamin E study consuming 18 g/d
olestra.
In the 4-week DC study in pigs, the reduction of vitamin A liver
stores in pigs fed 2.2 percent olestra was about 44 percent compared to
controls when olestra was fed admixed in the diet and about 14 percent
when olestra was fed in potato chips with all meals. Similarly, the
reduction of liver and serum vitamin E concentrations in pigs fed 2.2
percent olestra admixed in the diet was about twice as large (60
percent for liver and 52 percent for serum compared to controls) when
olestra was fed admixed as when olestra was fed in potato chips with
all meals (30 percent and 20 percent for liver and serum,
respectively). Therefore, the petitioner has concluded that the effects
of olestra that were measured in the 12-week DR, 12-week VR, 26-week
DR/VR, and 39-week VR pig studies were exaggerated by about 3-fold for
vitamin A and about 2-fold for vitamin E over what would have been
observed if the olestra were fed in chips with meals.
FDA agrees that when savory snacks containing olestra are eaten
without other foods, olestra's effects on fat-soluble vitamins will be
less than the effects measured in the 8-week human studies or in the
12-, 26-, and 39-week pig studies. However, FDA concludes that, given
the wide variety of possible dietary patterns, the most protective
approach is to ensure that compensation levels that accommodate most,
if not all of those dietary patterns. Slight overcompensation with
vitamins A, E, D, and K that might occur if an individual were to eat
all olestra-containing snacks separate from other foods would not raise
any health concerns, as discussed below. In contrast, the potential for
developing vitamin deficiencies in some of the population that
preferentially eat olestra-containing snacks with meals is of
sufficient concern to merit this approach. Further, calculating
compensation levels using the with-meal study results provides an
additional measure of safety, because based on the MRCA data, it is
probable that not all olestra consumed in savory snacks will be eaten
with meals. Therefore, FDA is not relying on the results of the
contextual studies or calculations based on eating patterns in
[[Page 3145]]
evaluating the safety of olestra with regard to nutrient effects.
b. Vitamin A. FDA and the petitioner agree that olestra's effects
on vitamin A present significant health concerns and, therefore,
compensation for olestra's interference with this vitamin's absorption
should be made. The pig studies show that olestra consumption has a
dose-response effect on vitamin A that is nonlinear, having the
greatest effect (on a per-gram-of-olestra basis) at low olestra
consumption levels. The level of vitamin A compensation was calculated
using data from the pig studies in which the effect of olestra and
olestra with added retinyl palmitate on vitamin status were determined.
Thus, the pig studies provide the most direct measure of vitamin A
status. Calculations were based on the effect at the lower olestra
doses to ensure that compensation is sufficient for all consumers.
Both the petitioner and FDA have calculated that 170 IU of vitamin
A/g olestra (51 retinol equivalents/g) compensates for olestra's
effects on vitamin A (from both preformed vitamin A and the provitamin
A carotenoids). This amount is equivalent to 0.34 times the RDA in a 1-
oz serving of savory snacks containing 10 g of olestra.
The results of the vitamin A/fat study in humans showed that only
the highest dose of olestra (32 g/d) had a measurable effect on
preformed vitamin A absorption. This direct measurement of olestra's
effect on absorption of preformed vitamin A in humans shows less of an
effect than the observed effect on vitamin A stores in the pig studies,
a difference likely due to the decreased absorption of carotenoids in
the pig studies, which are therefore less available as provitamin A
sources. Vitamin A added to olestra in the 12-week DR, 26-week DR/VR
and 39-week VR pig studies compensated for both the loss of preformed
vitamin A and carotenoids as provitamin A sources, as it would when
olestra is compensated in savory snacks. Therefore, FDA concludes that
relying on the pig data to calculate the compensation level will
account for olestra's effects on absorption of both preformed vitamin A
and carotenoids as contributors to the vitamin A body stores.
During the Olestra Working Group meeting, the members of the
Olestra Working Group unanimously agreed that FDA had appropriately
evaluated the amount of vitamin A with which olestra should be
compensated.\32\
\32\Transcript, vol. 3, pp. 220-225.
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At the FAC meeting, Dr. Rodier, an embryologist and member of the
FAC, expressed concern about the potential toxicity, especially
teratogenicity, of the vitamin A that would be added to olestra.\33\
She pointed out that since 1986, the Teratology Society has recommended
that vitamin supplements not contain preformed vitamin A, but that they
contain carotenoids instead. FDA is aware of a recent study
investigating the teratogenicity of vitamin A intake (Ref. 57), in
which an association was found between the prevalence of defects
associated with cranial-neural-crest tissue in babies and consumption
by their mothers of preformed vitamin A supplements during pregnancy.
The researchers found an apparent threshold for the effect of about
10,000 IU of supplemental preformed vitamin A (i.e., in addition to
vitamin A consumed in the diet). Consumers eating large amounts of
olestra might obtain a small amount of bioavailable vitamin A from
olestra because the compensation level was calculated from low olestra
doses where the effect/g olestra is the highest. However, because the
teratogenic effects seen by Rothman et. al., occur with vitamin A
intakes more than 10,000 IU above that which is consumed in the daily
diet, and because most of the vitamin A in olestra will remain in the
olestra as it passes through the body, FDA concludes that there is no
reasonable scenario of olestra consumption from savory snacks that
would lead to vitamin A leaching out of the olestra at levels anywhere
near 10,000 IU. Therefore, the agency is requiring vitamin A
compensation at 170 IU/g olestra (51 retinol equivalents/g).
\33\Dr. Patricia Rodier, is a senior scientist in the Department
of Obstetrics and Gynecology, University of Rochester. Transcript,
vol. 4, p. 99.
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c. Vitamin E. FDA and the petitioner agree that olestra's effects
on vitamin E present significant health concerns and, therefore,
compensation for this vitamin should be made. Serum data from the human
studies provide the basis for calculating the appropriate compensation
level for vitamin E, and the calculations are supported by the results
of the pig studies. The petitioner has calculated that 1.9 mg
-tocopherol equivalents (2.8 IU vitamin E) should be added per
g of olestra to compensate for olestra's effect on vitamin E levels.
This amount is equal to 0.94 times the RDA in a 1-oz serving of snack
containing 10 g of olestra. The compensation level calculated from the
pig studies for the lowest olestra consumption level (which shows the
largest effect when calculated per g of olestra) is 2.79 IU vitamin E/g
olestra, which is essentially the same as the compensation level
calculated from the 8-week human studies.
During the Olestra Working Group meeting, the members of the
Olestra Working Group unanimously agreed that FDA had appropriately
evaluated the amount of vitamin E with which olestra should be
compensated. Therefore, FDA is requiring vitamin E compensation at 2.8
IU/g olestra (1.9 mg -tocopherol equivalents/g olestra), which
will adequately compensate for olestra's effects in all realistic
consumption scenarios.
d. Vitamin D. The petitioner concluded that the effects of olestra
on vitamin D2 concentration do not warrant compensation with
vitamin D. As support, the petitioner cites the absence of changes in
serum 1,25-OH2D concentration in the pig studies as evidence that
olestra has no significant effect on overall vitamin D status despite
the decrease in dietary vitamin D2 status. Typically, the
contribution of dietary vitamin D to total vitamin D status in the
general population is from 10 to 20 percent (the rest from sunlight-
induced synthesis in the body). Therefore, the petitioner reasons that
a 23 percent decrease in dietary vitamin D status would result in only
a 2.3 to 4.6 percent reduction in overall vitamin D status in a normal
healthy human under the exaggerated conditions of olestra consumption
used in the studies. In worst-case situations, where dietary vitamin D
can contribute up to 50 percent of total vitamin D, the petitioner
calculates that the reduction in overall vitamin D status would be 11.5
percent when olestra was consumed with every meal.
FDA disagrees with the petitioner's position that the effect of
olestra on vitamin D is not sufficient to warrant compensation.
Although most individuals can produce vitamin D through exposure to
sunlight, there are some people who may not synthesize sufficient
vitamin D to compensate for potential decreases due to olestra effects,
either because they are not exposed to sufficient sunlight or because
they utilize sunlight poorly to synthesize vitamin D. Therefore, FDA
concludes that compensation for vitamin D should also be required for
olestra-containing foods.
From the 8-week human studies, the petitioner calculated that 0.07
g vitamin D2/g olestra (0.07 times the RDA per 10 g of
olestra) would be sufficient to compensate for the olestra-induced
decrease in 25-OHD2. FDA notes that in the 8-week VR study, 0.2
g vitamin D2/g olestra slightly overcompensated for
olestra's effects on vitamin D status, as measured by total 25-OHD
levels.
[[Page 3146]]
However, these values are based on only two compensation levels, and
may be confounded by the fact that serum vitamin D levels continued to
decrease over time in the study.
The petitioner has also calculated, from the 1.1 percent olestra
group of the 12-week DR pig study, that 13.0 IU vitamin D/g olestra
(0.33 times the RDA per 10 g of olestra) would compensate for olestra's
effects in that group. Although the design of that study also contains
some weaknesses, FDA believes that the results of both the pig study
and the 8-week human studies, considered together, support the need for
a compensation level and provide an approximation of an appropriate
level.
Given the importance of vitamin D, FDA concludes that it is
preferable to compensate consistent with olestra's demonstrated effects
on vitamin D, rather than risk a deficiency (Ref. 58). FDA concludes
that addition at levels of 12 IU vitamin D/g olestra (0.3 g/g
olestra) or 0.3 times the RDA per 10 g of olestra, is adequate to
compensate for any vitamin D that is lost due to diminished absorption
caused by olestra. This level of vitamin D includes the amount that was
observed to compensate for olestra's effects in the 12-week DR pig
study and is slightly higher than the 0.2 g/g that was
observed to be sufficient in the 8-week VR human study. During the
Olestra Working Group meeting, the members of the Olestra Working Group
unanimously agreed that FDA had appropriately evaluated the amount of
vitamin D with which olestra should be compensated.
This level of vitamin D compensation does not raise any toxicity
concerns, even if olestra as actually consumed has no effect on the
absorption of vitamin D, because it is generally accepted in the
medical community that one would have to ingest five times the RDA (the
RDA is 400 g of vitamin D) before toxicity effects begin to
occur (Ref. 59). Thus, slight overcompensation with vitamin D would not
cause health concerns. Assuming that the daily diet contains an RDA of
vitamin D, olestra would have to contribute four times the RDA (or
1,600 IU), which is equivalent to the amount added to about 13 oz of
potato chips, to reach levels where toxicity effects begin. However,
most of the vitamin D in olestra would not be bioavailable. Therefore,
FDA is requiring compensation with 12 IU vitamin D/g olestra (0.3
g/g olestra).
e. Vitamin K.--i. Petitioner conclusions. The petitioner concluded
that the effects of olestra on serum phylloquinone levels will not pose
a potential public health concern, and therefore, compensation of
olestra savory snacks with vitamin K is not necessary. The petitioner
based this conclusion on: (1) The absence of olestra effects on the
sensitive measures of vitamin K function under exaggerated conditions
of the studies conducted in humans; (2) the presence in the U.S. diet
of significantly more vitamin K than the single RDA fed in the studies
in which no effects on sensitive measures were observed; (3) the fact
that the dietary level of vitamin K associated with detectable effects
on sensitive functional parameters is well below the RDA; and (4) the
absence of either a dietary pattern consistent with, or clinical
evidence for, the existence of subgroups within the U.S. population at
risk of vitamin K deficiency.
The petitioner concluded that functional measures of vitamin K
status provide a reliable basis for public health decisions regarding
this vitamin, because these measures provide a direct assessment of the
ability of the vitamin K supplied to the tissues to maintain normal
vitamin K function. Because, unlike vitamins A, D, and E, there are no
significant phylloquinone stores in the body and serum concentrations
of the vitamin fluctuate significantly throughout the day, these
functional measures provide an integrated picture of the supply of
vitamin K over a time period as short as 2 to 3 days. Fasting serum
measures of phylloquinone, on the other hand, may not reflect the true
status of vitamin K because of the very short half-life of the vitamin
in the plasma (less than 2 hours). At any given time during the day,
the serum concentration of phylloquinone may suggest low or inadequate
vitamin K supply, while the tissues may be receiving more than adequate
amounts to support maximal rates of carboxylation.
The petitioner further concluded that urinary Gla excretion and
plasma des--carboxylated prothrombin (PIVKA-II) are the
markers of vitamin K function that best reflect the integrated vitamin
K status of the individual over time. If the phylloquinone supply from
the diet falls below a level adequate to support maximal synthesis of
vitamin K-dependent proteins in the body, PIVKA-II and urinary Gla will
change to reflect the inadequate supply. The half-lives of prothrombin
(Factor II) and of the vitamin K-dependent proteins which contribute
the majority of the urinary Gla excretion (60 hours or more) are
significantly longer than the half-life of phylloquinone in plasma
(about 2 hours). Therefore, the petitioner argues, these functional
measures provide a sensitive index of potential chronic effects on the
adequacy of vitamin K in the diet. Urinary Gla is particularly
important because it reflects carboxylation of vitamin K-dependent
proteins in all tissues, including bone and kidney. Although the
petitioner believes that compensation for vitamin K is unnecessary, the
petitioner has evaluated olestra's effect on vitamin K by comparing
serum vitamin K levels with vitamin K dietary intake at varying olestra
levels, and has determined that 3.3 g vitamin K/g olestra will
restore serum vitamin K levels to those of the control group. This
level is less than one-half of the 80 g RDA, when contained in
a 1-oz serving of savory snacks containing 10 g olestra. Because the 8-
week DR study was not designed to assess the olestra dose response for
vitamin K, the compensation level calculated by the petitioner is only
an estimate of an appropriate compensation level.
ii. FDA conclusions. FDA concludes that the data from the 8-week
human studies show that serum vitamin K levels were decreased by
consumption of olestra, and that the lack of effect on functional
assays could be attributable to the use of a subject population that is
not at risk for vitamin K deficiency. Similarly, as noted, the lack of
an olestra effect on prothrombin time in the pig studies may be
explained by the insensitivity of the analytical method and
oversupplementation of the test diet with vitamin K. While olestra may
not pose a health risk due to moderate reductions in serum vitamin K
levels for healthy adults consuming diets that, on average, provide
them with the minimum RDA for fat-soluble vitamins and other nutrients,
these reductions of vitamin K could be of concern for segments of the
population at risk for vitamin K deficiency or where the control of
blood clotting is more critical.
There were no studies designed to assess the dose-response nature
of olestra's effect on vitamin K. The pig studies are not useful in
this case because of the uncertainty regarding the activity of
menadione and phylloquinone in the swine diet and the likelihood that
the NRC requirements for swine are much higher than actual need. In
contrast, the 8-week DR study in humans is useful for estimating an
appropriate compensation level because the diet contained approximately
1 RDA of vitamin K and the dietary levels of vitamin K on the day
before blood draws varied for each blood draw.
FDA believes that the consequences of vitamin K depletion are
sufficiently serious and their onset so sudden as to warrant addition
of vitamin K to olestra-containing food. Also, it is well
[[Page 3147]]
recognized in the medical community that large doses of vitamin K can
be tolerated with no toxic effects.\34\ Thus, even if compensation with
vitamin K is not necessary for all olestra consumers, such compensation
poses no safety concern. FDA further believes it is appropriate to
require compensation at a level somewhat higher than that calculated
from the 8-week DR study, to provide a greater assurance of safety.
Given that the RDA is 80 g/d and vitamin K exhibits no known
toxicity, FDA recommended at the Olestra Working Group and the FAC
meetings that a level of 8 g vitamin K/g olestra, or one times
the RDA per 10 g of olestra, would provide an adequate compensation
level of vitamin K and would not cause any concern over toxicity.
\34\FDA is not aware of any toxic effects of phylloquinone. In
addition large quantities are routinely given for certain specific
situations. For example, infants usually receive a single dose of
0.5 to 1.0 mg vitamin K injected intramuscularly shortly after birth
to protect against bleeding.
---------------------------------------------------------------------------
During the Olestra Working Group meeting, the members of the
Olestra Working Group unanimously agreed that FDA had appropriately
evaluated the amount of vitamin K with which olestra should be
compensated. Although there was no disagreement among FAC members that
slight overcompensation with vitamin K would not be of concern to the
general public, a Working Group member\35\ and two presenters\36\
expressed concern about the effect that olestra consumption (whether or
not compensated with vitamin K) would have on persons for whom blood
clotting should be controlled, such as persons taking coumarin drugs.
\35\Donna Richardson, J.D., R.N., Howard University, Midlantic
Women's Health Initiative. Ms. Richardson is a member of the FAC
(Transcript, vol. 3, p. 255).
\36\Dr. Michael Jacobson, CSPI (Transcript, vol. 3, p. 179 and
vol. 4, p. 15), and Dr. Ian Greaves, Associate Professor, and Deputy
Director, Minnesota Center for Environmental and Health Policy,
University of Minnesota School of Public Health. Dr. Greaves
presented at the request of CSPI (Transcript, vol. 2, p. 267).
---------------------------------------------------------------------------
Dr. John Suttie, a researcher in the vitamin K field,\37\ responded
to these concerns. Dr. Suttie stated that monitoring of Coumadin
therapy is a well-recognized problem, and that Coumadin doses must be
titrated because of a number of adverse influences in such therapy. He
and the petitioner\38\ stated that diet is usually not one of the
primary factors of concern in anticoagulation therapy, even though
dietary vitamin K intake can vary day-to-day by three- to four-fold.
Dr. Suttie asserted that changes due to consumption of vitamin K-
compensated olestra would likely be within the normal range of dietary
variation.
\37\Dr. John Suttie is a biochemist and nutritionist at the
University of Wisconsin. Dr. Suttie consulted with the petitioner
and presented at its request. Transcript, vol. 3, p. 256.
\38\Dr. John Peters, Procter and Gamble, Transcript vol. 1, p.
147.
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FDA concurs with Dr. Suttie's statements and concludes that olestra
should be compensated with 8 g vitamin K/g olestra. The
majority of the FAC members also agreed that olestra should be
compensated with vitamin K, and that the level selected by FDA is
appropriate. FDA notes that if, in the future, the petitioner develops
data that demonstrate that a lower level of compensation would be
adequate, a petition could be submitted requesting an appropriate
change in the required compensation level.
f. Carotenoids.--i. Data and information regarding carotenoids. The
human studies demonstrate that consumption of olestra affects serum
carotenoid levels. The petitioner concludes, and FDA concurs, that
supplementing olestra with vitamin A will compensate for olestra's
effects on the provitamin A function of carotenoids. There was no
disagreement with this conclusion during the discussions at the Olestra
Working Group and FAC meetings. The petitioner also concluded that it
is not necessary to compensate olestra with any carotenoids, as there
are no established beneficial health effects (aside from their
provitamin A role) and further, that olestra's effect on carotenoid
availability in the body is likely to be much smaller than that shown
in the 8-week studies.
At the Olestra Working Group and FAC meetings, there was a thorough
discussion of the possible beneficial health effects of carotenoids in
preventing illnesses such as macular degeneration, prostate and lung
cancer, and heart disease and whether olestra's effects on carotenoids
would increase the risk of disease. In addition, the White Paper which
was provided to the Committee, addressed the potential detrimental
health impact of olestra's effect on carotenoids (Ref. 3). Information
was also presented on whether carotenoids themselves have beneficial
health effects, or whether it is other substances in the fruits and
vegetables that provide the health benefits, and that carotenoids are
serving solely as markers for fruit and vegetable consumption.
In his presentation to the Olestra Working Group,\39\ Dr. Meir
Stampfer, a professor of nutrition, stated that the results of an
epidemiological study showed that higher levels of carotenoid intake,
particularly lutein and zeaxanthin (which concentrate in the macula),
have a marked protective effect against macular degeneration (Ref. 60).
In addition, he stated that epidemiologic data show that individuals
with high levels of lycopene intake were at a lower risk for developing
prostate cancer a reduction that was statistically significant (Ref.
61). Dr. Stampfer also stated that there are many epidemiologic studies
showing that individuals with high levels of plasma or serum
carotenoids have a lower risk of lung cancer. Written information
provided to the Committee also discussed the role of carotenoids in
preventing cataracts, cardiovascular disease, and stroke.\40\
\39\Dr. Meir Stampfer is a professor of nutrition at Harvard
University School of Public Health. Transcript, vol. 1, p. 154. CSPI
also provided FDA with a letter from Dr. Stampfer and Dr. Walter
Willett prior to the FAC meeting. Dr. Stampfer presented at the
request of CSPI.
\40\See for example Refs. 3 and 62.
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Dr. Alvan Feinstein critiqued the epidemiological data for
carotenoids in his presentation to the FAC.\41\ Dr. Feinstein stated
that the epidemiologic evidence is not conclusive that carotenoids
reduce the incidence of cancer or any other disease. Dr. Feinstein
stated that epidemiologic case-controlled or other observational
studies are problematic because the baseline state of those studied is
not identified. In the studies of macular degeneration and of various
cancers, for example, the health or disease state of participants
before exposure is not known and differences may not be noted or
adjusted for. Also, the compared agents are ascertained in retrospect,
after they were taken; that ascertainment may be inaccurate or biased
by a knowledge of outcome events. In addition, epidemiological studies
lack reliability in terms of participants' accounts of what they ate or
did not eat in the past. Finally, in such epidemiologic studies it is
difficult to determine and adjust for the agent of interest (e.g.,
carotenoids, fruits, vegetables, or lycopenes).
\41\Transcript, vol. 1, p. 172.
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Dr. Feinstein stated that, given these limitations with
epidemiological studies, researchers, in general, are very reluctant to
draw causal conclusions from epidemiologic data and prefer to rely,
whenever possible, on randomized trials. One reason that randomized,
experimental trials are preferable for
[[Page 3148]]
establishing cause and effect relationships is that the baseline state
is clearly specified by the admission criteria, and the randomization
produces an equal distribution for the differences in susceptibility to
disease.
Dr. Feinstein discussed the results of the randomized trials
concerning the health effects of carotenoid. He stated that to date,
there have been five randomized trials of the effects of carotenoid
consumption on disease, and that the data thus far have shown no
convincing beneficial effect. A 1994 study in Finland assessed the
effects of dietary supplements containing -carotene versus
placebo with lung and other cancers and identified a possible harmful
effect of the carotenoid supplements.\42\ Other studies assessing the
possible association between carotenoid supplement intake and
nonmelanoma skin cancer (Ref. 64), and colorectal cancer (Ref. 65) also
established no difference between the carotenoid and placebo groups in
the selected outcome or in effects in the eye or coronary disease.
Finally, a study examined the association between a combination of
supplements (no placebos) and the death certificate diagnoses of cancer
and found no statistically significant differences (Ref. 66).
\42\Dr. Greaves mentioned that blood draws at the beginning of
the Finland study showed that men in the lower quartile for serum
-carotene in the blood had significantly higher incidence
rates of lung cancer than the men with the high levels of -
carotene in blood (Ref. 63).
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The assessment of the significance of olestra's depletion of serum
carotenoid should include consideration of the magnitude of the effect
compared to variations in carotenoid utilization. Dr. James Olson, a
professor of biochemistry,\43\ noted in his presentation to the Olestra
Working Group, that in the broader context of the diet, the effects of
olestra on carotenoid utilization when used in savory snacks will be
relatively minor, because a number of other factors influence
carotenoid utilization, including carotenoid stability,
bioavailability, and absorption. In the presence unsaturated fatty
acids such as vegetable oils, for example, carotenoid are very rapidly
destroyed. Similarly, carotenoid bioavailability can vary from almost
zero to about 50 percent, depending on the vegetable concerned, cooking
practice, and the presence and type of oils in the GI tract. (For
example, in butter fat or coconut oil, carotenoid are only about 50
percent as well absorbed as in more unsaturated oils.) Inhibitors to
carotenoid absorption also exist, including fiber, particularly acidic
pectins, and high concentrations of vitamin E. Dr. Olson subsequently
provided FDA with a published study that shows that the increase in
plasma -carotene concentration 30 hours following consumption
of a controlled meal containing 25 mg -carotene and 12 g
citrus pectin was only half as large as the increase observed in the
absence of citrus pectin (Ref. 67). Furthermore, Dr. Olson noted that
competitions occur between various carotenoid for absorption; in
particular, lutein, canthaxanthin, and -carotene mutually
inhibit each other's absorption.
\43\Dr. James Olson, Professor, Biochemistry and Biophysics
Department of Iowa State University, researcher in the filed of
carotenoid and vitamin A. Dr. Olson has consulted with the
petitioner and presented at its request. Transcript, vol. 3, p. 190.
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Although olestra does affect carotenoid absorption, the petitioner
asserted that only the more lipophilic carotenoid would likely be
affected by olestra. The petitioner presented data regarding the
octanol:water partition coefficients (PC's), a measurement of how fat-
soluble a substance is,\44\ for the various carotenoids, and noted that
substances with a log10 PC above about 7.5 can be affected by
olestra if they are consumed simultaneously with the olestra.\45\ Three
of the four carotenoids monitored (-carotene, -
carotene, and lycopene) are the most lipophilic carotenoids with
octanol:water PC's of approximately 17.6 each and would thus be
expected to be the most affected by olestra. Indeed, the 8-week studies
and 16-week vitamin E study show that the effects of olestra on the
serum levels of these carotenoids are very similar. Lutein and
zeaxanthin, which have more hydroxyl groups, are about 1,000 times less
lipophilic (PC's of 14.82 and 14.95, respectively) than -
carotene (Ref. 68).
\44\Octanol:water partition coefficients (PC's) are generally
expressed on a log scale so that a substance with a PC of 12 is 10
times as fat soluble as a substance with a PC of 11.
\45\Transcript, vol. 2, p. 125.
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In addition, it is possible that serum carotenoid levels are not
good indicators of carotenoid availability in the body. Dr. Olson
pointed out that the plasma carotenoids amount to approximately one
percent of the total tissue content of carotenoids. Plasma carotenoid
concentrations can vary fairly rapidly within 1 to 4 weeks whereas
tissue concentrations change much more slowly. Because protective
aspects of carotenoids would be expressed at the intracellular level,
plasma carotenoid concentrations, particularly in short-term studies,
may not be very accurate indicators of useful carotenoid levels.\46\
Similarly, Dr. Leonard Cohen,\47\ in a presentation to the Olestra
Working Group, also pointed out that serum measurements are single-
point at a certain time of the day, but that carotenoid levels have
Circadian rhythms. Therefore, one cannot tell at one point of the day
whether levels will be the same at another point of the day.
\46\Transcript, vol. 3, p. 192.
\47\Dr. Leonard Cohen, Section Head, Nutrition and
Endocrinology, American Health Foundation. Transcript, vol. 3, p.
149.
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Finally, Dr. Olson noted that five different conferences or
reviewing groups have examined the relationship between carotenoids and
disease: A U.K. Committee on the medical aspects of food policy (1987);
the Life Science Research Offices of the Federated American Societies
of Experimental Medicine in Biology; a European Union of Scientific
Committees for Food (1992); an International Life Sciences Workshop on
Antioxidants and Health (1993); and an FDA Conference on Antioxidant
Nutrients (1993). He stated that all of these groups concluded that
there is insufficient evidence to recommend specifically consumption of
carotenoids, except to encourage the consumption of vegetables and
fruit.
After considering all the presentations and information submitted
by CSPI in their White Paper (Ref. 3), a substantial majority of the
Olestra Working Group felt that there is a reasonable certainty of no
harm from olestra's effects on serum carotenoid levels.
However, some members of the Olestra Working Group voiced concern
about olestra's effects on carotenoid serum levels. Because of this
concern, FDA subsequently consulted with scientists at the National
Institutes of Health (NIH) and requested their views on whether
olestra's effects on lipophilic carotenoids raise any significant
public health issues with respect to the possible association between
carotenoids and cancer risk\48\ and macular degeneration\49\ (Refs. 69
and 70). The agency provided these scientists with copies of letters
concerning carotenoids that the agency had received (including the
letter from Dr.'s Willett and Stampfer (Ref. 62)), submissions by the
petitioner, excerpts discussing carotenoids from the White Paper, and
relevant sections of the Transcript from the Olestra Working Group and
FAC meetings.
\48\Dr. Peter Greenwald, Director of the Division of Cancer
Prevention and Control, National Cancer Institute, NIH.
\49\Dr. Carl Kupfer, Director of the National Eye Institute,
NIH.
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Regarding cancer risk, Dr. Peter Greenwald stated that the effects
of olestra on carotenoid utilization under
[[Page 3149]]
the conditions of use would be expected to be relatively minor, that
the provitamin role of carotenoids is the only function that has been
adequately documented, and that plasma carotenoid concentration (which
were used in the reported epidemiological studies) probably is not a
reliable indicator of tissue levels and may in fact be misleading.
Therefore, he concluded that no significant health issue was raised by
the reported effects of olestra on lipophilic carotenoids. Furthermore,
he recommended against supplementing olestra with -carotene or
other carotenoids at this time (Ref. 71).
Regarding macular degeneration, Dr. Carl Kupfer stated that
although theoretical considerations have raised the possibility that
carotenoids might play some protective role in macular degeneration,
there are currently no convincing clinical data to substantiate the
hypothesis. Furthermore, he asserted that no clear eye health benefit
has been demonstrated for carotenoids (Ref. 72).
ii. FDA's evaluation of olestra's effects on carotenoids.
On balance, having considered all the comments, data, and
information that the agency has received on this subject, FDA has
determined that the information currently available show that olestra's
effects on the absorption of the lipophilic carotenoids is reasonably
certain to be insignificant from a public health standpoint. First, FDA
has determined that the available data do not establish any
identifiable nutritional or prophylactic benefits for the carotenoids,
either individually or collectively. Specifically, controlled
randomized studies have been performed to test the potential cancer-
protective effects of carotenoid consumption and have shown no
association between carotenoid consumption and cancer.\50\ Also, there
have been no controlled studies to examine the association between
carotenoid consumption and eye disease.
\50\In fact, well-controlled studies indicate that there may be
higher incidence of lung cancer in smokers consuming high levels of
-carotene.
---------------------------------------------------------------------------
The agency believes that its conclusion regarding the absence of
harm from olestra's effect on some carotenoids, which conclusion is
based on the scientific evidence currently available, is not
inconsistent with the currently available epidemiological studies. This
is because the epidemiologic studies show an association between diets
rich in fruits and vegetables and decreased cancer risk and do not
evaluate the association between carotenoids per se and lower disease
risk. Thus, there is no direct evidence from these epidemiologic
studies that carotenoids are the substances responsible for the
protective effect. In fact, as noted by several experts, serum
carotenoid levels may simply be markers for consumption of fruits and
vegetables.
The agency's determination that olestra's effects on the absorption
of carotenoids is reasonably certain to be insignificant is bolstered
by the fact that the actual magnitude of olestra's effects on
carotenoid absorption is likely to be within the range of the normal
variation due to diet and bioavailability because the percentage of
consumed carotenoids that are actually available to the body is highly
variable and affected by a number of factors. In fact, the agency
believes that it is likely that olestra's effects on carotenoid
absorption will likely be substantially less that those observed in the
8-week studies and will be more similar to the effects observed in the
16-week vitamin E study.\51\ Finally, the association between serum
carotenoid levels and the availability of carotenoids at the cellular
level is unclear. Hence, the relationship between olestra's effects on
serum carotenoids and the body's utilization of carotenoids is also
unclear.
\51\While FDA finds that the petitioner's hypothesis that actual
reductions in carotenoid levels will be affected by consumption
patterns and will therefore be even less than those observed in the
16-week vitamin E study is plausible, the actual magnitude of the
effect is not supported with data at this time.
---------------------------------------------------------------------------
Therefore, FDA has determined, based upon the scientific evidence
that exists at this time, that there is currently no justification or
need to require compensation of olestra-containing foods with specific
carotenoids.\52\
\52\This conclusion is consistent with the recommendations of
the various conferences that have been held to examine the
relationship between carotenoids and disease and is also consistent
with FDA's decisions regarding health claims for antioxidant
vitamins and cancer (58 FR 2622, January 6, 1993.)
---------------------------------------------------------------------------
C. Effects of Olestra on Water-soluble Nutrients that are Hard-to-
Absorb or Limited in the Diet
The two 8-week clinical studies in the human and the two 12-week,
the 26-week DR/VR, and the 39-week VR studies in the pig were used to
assess olestra's potential effects on water-soluble nutrients. Iron,
folate, vitamin B12, and zinc status were measured in both the pig
and human studies. Vitamin B12 absorption was also measured in the
human studies. Calcium status was measured only in the pig studies,
because there are no non-invasive methods sufficiently sensitive to
assess calcium status in humans. The human and pig studies are
described in section V.B. of this document, and the methods used to
measure the status of calcium, zinc, iron, folate, and vitamin B12
are summarized in Table 4 (human studies) and Table 6 (pig studies).
1. Results and Conclusions from Human Studies
a. Vitamin B12. In the 8-week human DR and VR studies, there
was no change in serum measures of vitamin B12. However, 8 weeks
is insufficient to observe effects in serum, and the presence of excess
vitamin B12 in the diets likely reduced the sensitivity of the
studies to evaluate vitamin B12 status. The petitioner also found
that absorption of vitamin B12 did not change as a result of
olestra consumption in either 8-week human study, as measured by the
Schilling test. FDA notes that dietary levels of vitamin B12 were
approximately 2.2 and 1.7 times the RDA in the DR and VR studies,
respectively. However, this overfortification does not affect
interpretation of the results of the Schilling test because the level
of vitamin B12 in the diet is not a factor in the Schilling
test.\53\ FDA concludes that the results of the Schilling test shows
that olestra has no effect on vitamin B12 absorption in humans.
\53\The Schilling test is an acute test that measures the
absorption of a dose of radiolabeled vitamin B12
---------------------------------------------------------------------------
b. Iron. Measures of iron status were performed in the 8-week VR
study. The petitioner concluded that olestra had no effect on iron
status, and that sporadic, statistically significant trends with
olestra dose in one or more of the measures at one or more time points
resulted from differences in status at baseline or from a general
decrease in iron stores resulting from phlebotomy (drawing blood for
analysis). FDA agrees with the petitioner's conclusion that there were
no changes in all measures of iron stores, with the exception of serum
ferritin levels for both treatment and control groups. FDA further
concludes that the decreased serum ferritin levels were consistent with
loss due to phlebotomy (Ref. 73).
c. Folate. Folate status was monitored in the 8-week DR study in
which folate was consumed at levels between 80 and 120 percent of its
RDA. There was no olestra dose response on the indices for folate
(serum and red blood cell folate concentration). FDA considers red
blood cell folate levels to be excellent
[[Page 3150]]
indicators of folate status.\54\ Thus, the agency agrees with the
petitioner's conclusion that olestra consumption does not affect folate
status.
\54\Transcript, vol. 3, p. 117.
---------------------------------------------------------------------------
d. Zinc. Zinc status was evaluated in the 8-week DR study. There
was no olestra dose response on the indices for zinc that can be
measured noninvasively in humans (serum and urinary concentration). FDA
agrees with the petitioner's conclusion that there is no evidence that
olestra affects zinc status. However, the agency notes that serum and
urinary concentrations are not sensitive indicators of zinc status in
humans. Although these data are not particularly sensitive indicators
of zinc status, FDA finds that the data support a finding of no effect.
However, FDA does not consider the data sufficiently sensitive to
support, in and of themselves, a conclusion of no effect.
2. Results and Conclusions from Pig Studies
Data from the studies of olestra consumption in pigs generally
corroborate the findings from the human studies regarding the effect of
olestra on iron and zinc status. Although, the results of the pig
studies regarding vitamin B12, calcium, and folate, do not
indicate any effect of olestra, these studies are of limited utility in
assessing olestra's effects because of several weaknesses in study
design, as discussed below.
a. Vitamin B12. There were no statistically significant
effects of olestra on liver vitamin B12 in the 12-week VR, the 26-
week VR/DR, and the 39-week VR pig studies. In the 12-week DR study, a
statistically significant downward trend in liver vitamin B12
levels, produced by a low value in the 7.7 percent olestra group, was
observed. There were no statistically significant decreases in the 1.1
percent, 2.2 percent, 3.3 percent, 4.4 percent, or 5.5 percent olestra
groups. The low value in the 7.7 percent olestra group was not
accompanied by an elevation in mean corpuscular volume, and thus, the
petitioner concluded that this decrease did not represent a change in
vitamin B12 status. (FDA notes that the downward trend was not
found in other pig studies.)
FDA concludes that the pig studies are limited in their usefulness
in assessing olestra's effects on vitamin B12. FDA's principal
reservation is that the level of vitamin B12 was measured only in the
diet premix and not in the complete diets; such analysis of the premix
is not as reliable as analysis of the complete diet because an
accidental mixing error may have occurred or the vitamin may have been
degraded or spared from degradation by an interaction with another
ingredient during the mixing process or during storage. Accordingly,
FDA finds that, although there was no consistent effect of olestra on
vitamin B12, these pig studies are inadequate by themselves to
evaluate olestra's effect on vitamin B12.
b. Iron. A battery of tests (liver iron concentration, serum total
iron binding capacity, and serum total iron concentration) conducted in
the 12-week VR, 26-week DR/VR, and 39-week VR studies showed no adverse
effects on iron status when olestra was fed at any level (up to 7.7
percent of the diet). There were statistically significant decreases in
liver iron values in the 12-week DR study in both the 5.5 percent and
7.7 percent olestra groups. However, in these groups, mean corpuscular
hemoglobin, mean corpuscular hemoglobin concentration, and red blood
cell count were unaffected by olestra consumption. The petitioner
postulated that the trend in liver iron concentration was probably
secondary to the poor vitamin A status of the animals, and thus,
concluded that iron status was not affected by olestra.
FDA notes that there was a large variability in liver iron values
in all pig studies. FDA postulates that the variability in liver iron
levels may have been due to several factors, such as blood loss from
gastric ulcers, dewclaw lesions or abscesses, or differences in the
amount of blood present in the liver after sacrifice. FDA further notes
that the test diets were oversupplemented with iron in that the diets
contained between 1.7 to 2.4 times the NRC requirements. FDA finds that
these results make it possible to rule out gross effects on iron status
but the foregoing factors make it difficult to exclude subtle effects
in these studies (Ref. 56). Accordingly, FDA finds that the pig studies
are inadequate by themselves to evaluate olestra's effect on iron.
c. Folate. The petitioner stated that there were a few
statistically significant differences in plasma folate concentration at
week 4 in the 26-week DR/VR study, but the values in the olestra groups
were greater than the control. There were no statistically significant
changes in plasma folate in the two 12-week studies, nor in the 39-week
VR study. Therefore, the petitioner concluded that folate status in
pigs was not affected by olestra consumption.
FDA finds that a conclusion on folate status cannot be drawn from
the pig studies for several reasons. First, no measurements of folacin,
either in the premix or in the diet as fed, were made in any of the
studies. Second, folic acid was added to the diet, rather than
folylpolyglutamates, the predominant form of folate in the American
diet. Folic acid (folylmonoglutamate) is absorbed directly, while
folylpolyglutamates must be cleaved by folylpolyglutamate hydrolase in
the intestine prior to being absorbed. Therefore, folacin is not a
hard-to-absorb nutrient when it is supplied as folic acid, as in these
studies. Finally, plasma folate is not as sensitive a measure of folate
status as red blood cell folate (the method used in the human studies).
Therefore, FDA concludes that the pig studies are of limited utility in
assessing olestra's effects on folate (Ref. 56).
d. Zinc. There were no significant effects of olestra on liver,
bone, or serum zinc levels in the 12-week DR study or the 26-week DR/VR
study. The only significant differences from control values in these
three measures of zinc status in the 12-week VR and 39-week VR studies
were small (and probably spurious) increases in liver zinc in the 0.25
percent low vitamin group in the 39-week VR study and in serum zinc in
four olestra groups at week eight in the 12-week VR study. Accordingly,
the petitioner concluded that liver, bone, and serum zinc
concentrations were not affected by olestra in any of the pig studies.
In general, FDA concurs with this conclusion, with some
qualifications, as discussed below.
Although they did not show any significant differences, the bone
zinc measurements are less than an ideal means of assessment because
the methodology used to analyze the bone has several flaws that limit
the power and reliability of the results. (These flaws are discussed in
the calcium section below.) Because of these methodological flaws, FDA
concludes that the bone zinc measurements of the pig studies do not
provide a completely reliable assessment of zinc status.
FDA notes that liver and serum measurements of zinc, in controlled
swine studies, are acceptable measurements of zinc status that have
sensitivities comparable to properly performed bone measurements. A
potential confounding factor in the assessment of zinc status in the
pig studies is the amount of zinc in the test animal diets. FDA
estimates that zinc consumption in the 12-week VR, 26-week DR/VR, and
39-week VR studies exceeded the NRC requirements by at least 68
percent. However, a review of the literature shows that serum and liver
zinc measurements will reflect dietary zinc over a wide range of
dietary
[[Page 3151]]
concentrations in controlled swine studies. Therefore, FDA believes
that this oversupplementation would not mask any effects of olestra on
zinc status. FDA concludes, therefore, based on the results of the
liver and serum measurements in these studies, that there is no
evidence that consumption of olestra affects zinc status.
e. Calcium. Bone ash and bone calcium levels were not affected by
olestra consumption in the 12-week VR, 26-week DR/VR, or 39-week VR pig
studies. The only change was seen in the 12-week DR study where bone
ash but not bone calcium was less (60.6 2.0 vs. 61.1
1.0 percent) in the 4.4 percent olestra dose group than in
the control group (Refs. 74 and 75), a difference that was
statistically significant. The other dose groups showed no
statistically significant change in bone ash or bone calcium. The
petitioner concludes that these results demonstrate that olestra
consumption does not have an effect on calcium status.
FDA concludes that the results from the pig studies are not useful
for determining whether olestra has any subtle effects on calcium
status; the results show only that there were no gross changes in
calcium status. FDA's determination that these studies are seriously
limited in their utility to determine calcium status changes is based
on two factors: oversupplementation of calcium in the diet and flawed
methodology in measuring bone ash and bone calcium.
FDA believes that the bone ash measurements are not reliable
because the test animals' diet was oversupplemented with calcium.
Specifically, test animals received approximately 1.0 to 1.3 times the
NRC calcium requirements during the 12-week studies (with the greater
amounts during the last 7 weeks) (Refs. 76 and 53), and 1.2 to 1.7
times the NRC requirement during the 26-week DR/VR and 39-week VR
studies (Ref. 52). Based on published studies (Refs. 77 and 78), FDA
believes that bone ash will reach maximum levels when dietary calcium
is approximately 1.2 times the NRC requirement and adequate levels of
phosphorus are provided (Ref. 56). Therefore, the supplementation above
1.2 times the NRC requirement would mask any subtle effect on calcium
absorption.
In the 26-week DR/VR and 30-week studies, olestra would have to
have inhibited the absorption of approximately 30 percent of the
calcium before any adverse effects on bone ash would have been observed
(Ref. 56). Thus, the bone ash data from these studies are not a
stringent test of calcium status. Although the oversupplementation in
the 12-week studies would not mask olestra effects on calcium as much
as it would in the 26-week DR/VR and 39-week VR studies, methodological
factors in obtaining the data on bone ash, as described below, in
combination with the slight oversupplementation during the last 7
weeks, make the calcium data only useful in determining whether there
were gross effects of olestra on calcium status.
Factors that CFSAN considers contributing to the limitations of the
methodology that was used to evaluate bone ash include the following:
(1) Only half of the bone selected for analysis (the L5 lumbar
vertebra) was used, rather than using the whole bone; (2) after drying
and grinding the half bone, an aliquot of the ground bone
(approximately 1.5 g) was taken for fat extraction, rather than
extracting the entire sample; (3) an aliquot (approximately 0.5 g) of
the fat-free bone powder was ashed, rather than ashing the entire
sample; and (4) ashing was performed at 500 deg.C for 8 hours, rather
than more typical conditions of > 550 deg.C for > 12 hours (Ref. 79).
Because of these methodological flaws, FDA concludes that the bone
ash and bone calcium measurements performed in the pig studies do not
provide a reliable assessment of calcium status.
Although FDA finds that the data from the pig studies are of
limited use in determining whether olestra affects the absorption of
calcium because the test diet was overfortified with calcium and
appropriate measures of bone were not made, FDA notes that the animals
grew normally and all outward observations indicated that they had
normal skeletal growth.
3. Overall Conclusions Regarding Olestra's Effects on Water-Soluble
Nutrients
The agency received no significant comments expressing concern
about olestra's effects on water-soluble nutrients. Similarly, Dr.
Connie Weaver, FDA's consultant on water-soluble nutrients, also found
no basis for concern (Ref. 75). FDA's specific conclusions on these
nutrients follow.
a. Vitamin B12. FDA has determined that there is no need for
compensation of olestra-containing foods with vitamin B12. In
reaching this conclusion, the agency relied primarily on the 8-week
human DR and VR studies in human to evaluate the effect of olestra on
vitamin B12. Both studies showed no effect of olestra on vitamin
B12 using the Schilling test, which is a sensitive test that is
not affected by dietary vitamin B12 levels. The vitamin B12
results of the pig studies are consistent with the results of the human
studies. In the pig studies, no effect of olestra was seen in the 12-
week DR, the 26-week DR/VR, or 39-week VR studies. There was a
statistically significant decrease in liver B