DIETARY SUPPLEMENT HEALTH CLAIMS FOR ANTIOXIDANTS EXPLICITLY DISALLOWED
This article was originally published in The Tan Sheet
DIETARY SUPPLEMENT HEALTH CLAIMS FOR ANTIOXIDANTS EXPLICITLY DISALLOWED by FDA along with health claims for four other nutrient-disease relationships under a proposed rule slated for publication in the Oct. 12 Federal Register. In the notice, the agency said it proposing "not to authorize health claims relating to an association between fiber and cancer, fiber and heart disease, antioxidant vitamins and cancer, omega-3 fatty acids and coronary heart disease [CHD], and zinc and immune function in the elderly on the labeling of dietary supplements." FDA declared that it has "tentatively determined that there is not significant scientific agreement among experts that claims on these nutrient-disease relationships are supported by the totality of publicly available scientific evidence," and that the agency is therefore making it "explicit that health claims" for the five relationships "are not authorized for foods in conventional food form or for dietary supplements." The proposal carries a 60-day comment period. Although FDA issued a proposal implementing the health claim provisions of the Nutrition Labeling & Education Act for supplements in June ("The Tan Sheet" June 21, p. 4), the agency noted that it "did not address the specific nutrient-disease relationships." Instead, FDA made dietary supplements subject to the same standards and procedures for using health claims that are required for conventional foods. FDA Office of Special Nutritionals Director Elizabeth Yetley, PhD, reported at the Council for Responsible Nutrition's recent annual conference in Washington, D.C. that FDA was working on such a proposal. She noted that FDA would be "reopening" the comment period for "health claim topics which were not approved" in the January NLEA final rule ("The Tan Sheet" Sept. 27, In Brief). In FDA's January 1993 NLEA implementing regs, the agency prohibited health claims for the same five nutrient-disease relationships plus folic acid claims for preventing neural tube defects. However, FDA has decided to authorize a folic acid claim for conventional foods and dietary supplements in a separate Oct. 12 Federal Register notice. The January final rule for foods also allows health claims for seven nutrient-disease relationships: calcium and osteoporosis; sodium and hypertension; fat and cancer; saturated fat and cholesterol and CHD; fiber-containing grain products, fruits and vegetables and cancer; fiber-containing fruits, vegetables and grain products and the risk of CHD; and fruits and vegetables and cancer. Three of the seven health claims authorized for foods, FDA emphasized in the Oct. 12 notice, "were for fresh fruits and vegetables and grains, and thus these claims are not authorized on dietary supplements." Regarding a health claim for antioxidant vitamins and cancer, FDA said it has tentatively determined, "based on the totality of publicly available scientific evidence, that there is not a sufficient basis to authorize a health claim." The notice does not address recent research findings that vitamin E may have potential cardiovascular protective effects. While people with "diets rich in fruits and vegetables experience many health advantages, including lower rates of some types of cancers," FDA continued, "it is not possible to specifically determine that the two antioxidant vitamins (beta, carotene and vitamin C) that are contained in fruits and vegetables are responsible for this effect." In explaining its rationale for determining that antioxidant vitamins should not carry a cancer prevention claim, FDA avoided addressing research findings on supplement use that have been published since the January NLEA rule and, instead, theorized about the possible beneficial effects of food substances that are either unknown or have not been measured in studies. The agency declared that it cannot "rule out the possibility of significant protective effects from nonmeasured components" in fruits and vegetables that contain vitamin C and beta carotene. The agency concluded that "there is not significant scientific agreement as to whether the observed protective effects of fruits and vegetables are the result of a single or combined effect of the antioxidant vitamins and other nutrients with antioxidant functions (e.g., selenium), to other nutritive compounds in such foods, to unmeasured components of such diets, or to displacement of other known risk components within the total diet." FDA emphasized that the Oct. 12 proposal provides an "opportunity for interested persons to submit new scientific data and comments on the five nutrient-disease relationships" disallowed by the document. The "available science" on antioxidants will be the focus of a Nov. 1-3 public symposium ("The Tan Sheet" Sept. 27, In Brief). FDA said the meeting will "identify any unmet research needs" and discuss "ways of facilitating research to meet these needs." Regarding omega-3 fatty acid supplements and their potential effect on heart disease, FDA pointed to its position in the NLEA final rule that there are "numerous physiological effects (e.g., increased bleeding times) of consumption of omega-3 fatty acids, but that at present, these endpoints are not generally accepted as being closely related to the risk of CHD." Because dietary supplements would contain only omega-3 fatty acids, "and there is not sufficient evidence that the omega-3 fatty acids alone caused the effects that were observed in studies of the effects of fish consumption on CHD, FDA tentatively finds that an appropriate basis" does not exist for allowing a health claim for omega-3 fatty acids, according to the notice. On claims for fiber supplements and cancer risk reduction, FDA again referred to its findings in the January NLEA regs for foods. Most of the studies that evaluated the potential link between fiber and cancer did not provide "evidence of an independent contribution of fiber itself (distinct from its presence in food) to risk reduction. Rather, the studies showed a relationship between diets rich in fiber-containing foods and a reduced risk in cancer," FDA stated. Overall, FDA concluded that "the available data are not sufficiently conclusive or specific for fiber to justify authorization of a health claim," especially because "there is no evidence that any specific fiber itself caused the effects that were seen in studies involving fiber-rich fruits, vegetables and grain products." FDA also prohibited health claims for dietary fiber and a reduced risk of cardiovascular disease based on an evaluation of "publicly available scientific evidence." A "major limitation in designing and evaluating research studies," the agency outlined, "has been the need for better defined measures of dietary soluble fiber and standardized descriptions of source, type and amount of dietary soluble fiber." "The inability to detect many of the differences among fibers, fiber components, and other substances in foods that contain soluble fiber, and the general lack of conclusions regarding the mechanisms of action for soluble fibers, raise questions about the ability of commonly used analytical methods to adequately predict biological actions of specific fibers," FDA pointed out. Therefore, currently available scientific evidence, the agency summarized, is "not sufficiently conclusive or specific for soluble fiber to justify the use of a health claim." Regarding a health claim that zinc boosts immune function in the elderly, FDA concluded that It although it is well accepted that adequate dietary zinc is essential for normal immune function, a specific protective role of zinc supplementation of the elderly population has not been demonstrated." Moreover, "there is some evidence in recent well-controlled studies that high levels of zinc intake will suppress immune function," the agency added. FDA said it plans to adhere to the statutory deadlines for publication of final rules implementing the NLEA for supplements - - Dec. 15 -- but lamented that "the agency has limited resources to both prepare the final rules that yet remain to be done under" the NLEA and to "carry out the administrative activities required by the final rules" for foods and supplements under the NLEA. FDA concluded the notice by emphasizing that it recognizes the "emerging nature of the scientific information regarding the relationships between the intake of nutrients and disease or health-related conditions" and cited the "full airing of the scientific data and other relevant information" on the five nutrient-disease relationships as a "primary objective."
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