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Article Excerpt
The U.S. marketplace for dietary supplements is large and changing rapidly. National surveys indicate that dietary supplements are used by roughly 50 percent of the U.S. population (Balluz, Kieszak, Philen, & Mulinare, 2000; Slesinsky, Subar, & Kahle, 1995). Industry sources suggest that sales of all forms of supplements combined--including nutrients, herbals, sports products, and meal supplements--rose from $8.6 billion in 1994 to $16 billion in 2000 (Heasman & Mellentin, 2001). During that same period, sales of nutrient supplements, specifically, rose from $3.9 billion to $6.1 billion. This rise in consumption of dietary supplements is only the beginning of a much larger "functional foods revolution" built upon the development and marketing of a wide variety of supplements, genetically engineered foods, fortified foods, and conventional foods with compositional properties that are perceived or marketed as having links to improved health, performance, or well-being (Heasman & Mellentin, 2001). The U.S. market for functional foods is estimated to rise from about $20 billion in 2000 to $50 billion by 2010 (Government Accounting Office [GAO], 2000).
The rapid rise and high prevalence of supplement use in the United States stand in marked contrast to the views and positions of professional and scientific nutrition communities. Organizations such as the American Dietetic Association (ADA) (Hunt, 1996), the Dietary Guidelines for Americans Advisory Committee (U.S. Department of Agriculture [USDA] & U.S. Department of Health and Human Services [DHHS], 2000), and the Food and Nutrition Board of the Institute of Medicine (IOM, 1994) have maintained that most individuals can and should obtain all necessary nutrients in adequate amounts from a varied diet and that supplements are needed only in special circumstances. The position of the ADA regarding supplementation is that
the best nutritional strategy for promoting optimal health and reducing the risk of chronic disease is to obtain adequate nutrients from a wide variety of foods. Vitamin and mineral supplementation is appropriate when well-accepted, peer-reviewed, scientific evidence shows safety and effectiveness. (Hunt, 1996, p. 73)
Notwithstanding the views of the ADA, the Food and Drug Administration (FDA), and other professional and scientific bodies, Congress created the Dietary Supplement Health and Education Act in 1994 that has little or no requirement for manufacturers to demonstrate the safety and efficacy of dietary supplements and is more permissive than conventional foods regarding the claims that marketers can make about the benefits of these products. In a recent report, the GAO (2000) concluded that the
FDA's efforts and federal laws provide limited assurances of the safety of functional foods and dietary supplements [and] ... we also found that agencies' efforts and federal laws concerning health-related claims on product labels and in advertising provide limited assistance to consumers in making informed choices and do little to protect them against misleading and inaccurate claims. (pp. 4-5)
While nutrient supplements taken in moderation do not raise the same safety concerns as do herbals and other dietary supplements, they do raise two other issues. One is their low efficacy in individuals and populations that do not suffer from nutrient deficiencies (USDA, 1999). In such cases, the exaggerated marketing claims regarding their benefits may mislead some consumers. While most studies show that supplement use is more common among Whites, women, those with higher levels of education, and those with higher incomes (USDA, 1999; Koplan, Annest, Layde, & Rubin, 1986; Lyle, Mares-Perlman, Klein, Klein, & Greger, 1998; Pelletier & Kendall, 1997), usage is not restricted to those groups. For instance, analysis of the 1994-95 Continuing Survey of Food Intakes by Individuals (CSFII) reveals that supplements were used by 49 percent of higher income individuals (greater than 130 percent of the poverty line) and 36 percent of lower income individuals (USDA, 1999).
The second issue related to nutrient supplements is whether they are used as true supplements for an already healthful diet or as a substitute for such a diet. This is important because of the wide range of health-promoting substances contained in whole foods, compared with supplements, which still are far from being understood fully. Most studies have shown that supplement users, compared with nonusers, tend to have higher vitamin and mineral intakes from food (Koplan et al., 1986; Looker, Sempos, Johnson, & Yetley, 1998; Lyle et al., 1995), suggesting a supplementing effect rather than a substitutive effect. Those studies have, however, assumed that such a finding applies equally to all consumers. The one study that examined potential heterogeneity in that relationship revealed that supplement use is associated with more healthful food intakes in some population groups but also is associated with less healthful food intakes in other groups defined by sociodemographic or attitudinal characteristics (Pelletier & Kendall, 1997).
The present study was initiated within the context of a rapidly expanding dietary supplement industry, a permissive set of laws and regulations, continued uncertainty regarding safety and efficacy, and questions concerning the positive or negative relationships between supplement use and the quality of food intake. The specific motivation for the study was the proposal considered by Congress on numerous occasions in the last decade to permit the use of food stamps to purchase nutrient supplements. This proposal was included in a House bill leading up to the welfare reform effort in 1996 (H.R. 104-236) and more recently in a Senate bill (S. 1731) leading up to the 2002 Farm bill. The proposal has yet to be incorporated into legislation on these and other occasions.
An expert committee of the Life Sciences Research Office (LSRO, 1998) and the USDA (1999) raised a number of...
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