NUTRITIONAL SUPPLEMENTS HAVE "NO EFFECT" ON ATHLETIC PERFORMANCE

NUTRITIONAL SUPPLEMENTS HAVE "NO EFFECT" ON ATHLETIC PERFORMANCE when taken above recommended daily allowances and in certain cases may be harmful, according to a literature review published in the December edition of Clinical Pharmacy. Susan Durden Beltz, PharmD, et al., Shands Hospital, noted that athletes frequently consume certain nutritional supplements to enhance athletic ability. However, the authors concluded that the supporting studies are "marred by flawed design" and "very few" of the studies have been published in peer-reviewed journals. The authors noted that, unlike anabolic steroids, the use of supplements does not bar athletes from competition. After reviewing the existing literature on the substances frequently touted as ergogenic -- including vitamins and minerals, protein supplements, carnitine, ginseng, chromium, growth hormone releasers, octacosanol and cobamamide -- Beltz et al. contended that "athletes may unknowingly be wasting their money on products that may not work and could be jeopardizing their health." Of the six classes of nutrients frequently supplemented by athletes, vitamins and minerals are used most often, the article notes. The authors contended that, based on the existing literature, "supplementation with vitamins in excess of RDAs has no effect" on athletic performance and "does not prevent injury when a deficiency state does not exist." Moreover, the authors asserted, there is "no strong evidence to suggest t at athletes have increased utilization, destruction, or loss of vitamins associated with exercise that would necessitate supplementation." The authors pointed out that at one time B-complex vitamins were believed to have ergogenic potential because they are coenzymes in the metabolism of fats and carbohydrates and are also involved in the production of erythrocytes. However, Beltz et al. maintained that current studies show no value of these vitamins when taken in excess of RDAs on athletic performance. In addition, early reports indicating that vitamin C may play a role in wound healing have not been supported by later studies, the authors found. Athletes' protein needs are less clear, the authors acknowledged. However, they noted that while "athletes may require slightly more protein than sedentary people do to maintain positive nitrogen balance," there is no evidence in the literature to demonstrate that "extra dietary protein will help someone to achieve athletic goals." Beltz et al. also pointed out that "purified amino acids have become a popular form of protein supplementation" for body builders without scientific evidence to support their use. Amino acid supplements, the authors maintained, are produced by "large- scale microbial fermentation processes and can be very expensive." Manufacturers, the authors asserted, claim that the extra cost is warranted for absorption purposes in order to optimize the supplements" potential for increasing muscle mass. "Many of these marketing claims are based on extrapolations from limited data," the authors contended. Beltz et al. called for "reputable, double- blind controlled studies" to "establish the true effects" of commercially available protein and amino acid supplements. Furthermore, many of the supplements on the market supply relatively little protein, the authors asserted. The researchers compared Joe Weider's Dynamic Protein Shake, which provides 16 grams of protein, to a 3.5-ounce serving of chicken without skin, which provides 30.9 grams of protein, and a three-ounce serving of tuna, which provides 25.1 grams of protein. "It is easy to see that careful dietary selection can adequately meet an athlete's protein requirement without the need for supplementation," the authors stated. The authors cited several studies that suggest that "athletes require more chromium than sedentary individuals." However, the authors questioned whether the study results reflected widespread chromium deficiencies that, according to another study, may affect "up to 90% of the general population." Beltz et al. noted that chromium deficiency "might have detrimental effects on athletic performance, but whether chromium supplementation has an ergogenic effect when a deficiency does not exist is another question entirely." The authors suggested that "more research seems warranted" on possible chromium benefits. The study authors also found that claims that carnitine, cobamamide, growth hormone releasers, octacosanol or ginseng enhance an athlete's performance are not supported by the studies that have been conducted thus far. Beltz et al. reported that none of the athletic performance tests involving these nutrients demonstrate that they improve athletic performance in a statistically significant way. They also said that while ginseng and growth hormone releasers should be evaluated further as to their adverse effects, cobamamide, carnitine and octacosanol do not appear to demonstrate a pattern of toxicity. Manufacturers of nutritional supplements in general, the authors maintained, "have gotten away with making entirely unsubstantiated claims about the ergogenic potential of a product as long as the product does not pose a danger to the consumer or the FDA does not receive a large number of consumer complaints." Beltz, et al. asserted that labeling and packaging "should not make claims of effectiveness for a particular use." Instead, they suggested that "pharmacists are in an ideal position to retrieve and interpret published data for the public." The authors also advised that more rigid quality control standards for nutritional supplement manufacturers are warranted, citing one "sampling" where 25% of the products purported to contain ginseng "contained no ginseng whatsoever."