Food Additives Permitted for Direct Addition to Food for Human Consumption; Olestra
Federal RegisterJan 30, 1996
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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.
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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 oles
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