DIETARY SUPPLEMENT FORMULATION "CANNOT REASONABLY BE BASED" ON RDAs
This article was originally published in The Tan Sheet
DIETARY SUPPLEMENT FORMULATION "CANNOT REASONABLY BE BASED" ON RDAs, or any multiple of the Recommended Dietary Allowances, Council for Responsible Nutrition Executive Director Annette Dickinson, PhD, told a public meeting sponsored by the Food and Nutrition Board (FNB) of the National Academy of Sciences on June 28. Noting that FNB's most recent RDA publication in 1989 "acknowledges that the RDAs are not intended to represent optimum intakes," Dickinson said that "neither the RDA nor any simple, across-the-board multiple is appropriate" for dictating the levels of vitamins and minerals contained in supplements. Rather, those levels should be considered nutrient by nutrient based on the biologic function, according to Dickinson. Although Dickinson acknowledged that "for some nutrients, there may indeed be no rationale for consumption of higher than RDA levels," she suggested that "for other nutrients, such as vitamin E or vitamin C, there may be abundant scientific support for the likely benefit of intake at levels considerably in excess and largely unrelated to the RDA." Dickinson added that "in the case of the antioxidants, in particular, the function of the higher level of the nutrient is indistinguishable from the function of lower intakes." Regarding the safety of some nutrients, she noted that "there may be safety considerations which need to be addressed at intakes which are, in fact, not greatly in excess of the RDA." Examples of such nutrients include vitamin A and vitamin D, Dickinson said, while other nutrients, such as thiamine, riboflavin, and beta carotene, "are generally recognized to have no known toxicity." Although currently the "nutrient reference standards developed by FDA for food labeling purposes are the most prominent feature of dietary supplement labeling," Dickinson concluded from market research conducted through CRN that "the vast majority of vitamin and mineral supplements on the market today are formulated largely without any meaningful reliance on the U.S. RDAs as a driving force for formulation." Multivitamins are the "extremely important exception" to this, Dickinson said, noting that multivitamins comprise 42% of the dietary supplement market. Dickinson added that the RDA levels were adhered to most uniformly in supplements marketed for children. "It seems evident that within the dietary supplement industry, and among many consumers of supplements, RDAs are not, in fact, viewed as optimal targets for nutrient intake and, accordingly, are not viewed as optimal guidelines for supplement formulation," Dickinson stated. According to CRN market research, 58% of dietary supplements on the market are nutrient-specific formulations that often contain megadoses of micronutrients such as vitamins E and C. Dickinson reported that the antioxidants were a rapidly growing segment: beta carotene supplement sales grew 32% in 1992, compared with 19% growth for the overall dietary supplement category. Dickinson characterized FDA's June 18 advanced notice of proposed rulemaking on dietary supplements ("The Tan Sheet" June 21, p. 1) as a return by the agency to "the notion that it may be possible to establish product limits based on the RDA or some other multiple of the RDA, either on grounds of rationality or on grounds of safety concerns." Dickinson noted that a similar motion by FDA to set nutrient supplement upper levels at 150% of RDAs was repeatedly overturned in the 1970s. Until such time as the board establishes safe levels of nutrients for optimal health benefit, Dickinson said that CRN would support "legislation that would require FDA to develop new label reference standards which do in fact take into account the levels of nutrients that have been shown to be associated with decreased risk of chronic disease, or the levels likely to be contained in diets, meeting the dietary guidelines, for example, of the [National Cancer Institute's] five-a-day [vegetable diet] program," Dickinson said.
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