Over-the-Counter Sports Supplements: What Clinicians Need to Know

Federman DG, Kenkare ZN

Due in part to endorsements by professional athletes, nutritional sports supplements have experienced increased popularity. Because the supplements are thought of as "natural," they are also considered to be safe by users. However, studies have shown that the supplements are often not used according to directions, and physicians are not consulted about safety or efficacy before use. This article discusses four popular supplements and aims to educate physicians on the potential benefits and risks of these supplements. Creatine Manufacturers claim that creatine increases lean body mass, strength, and endurance and decreases muscle soreness. A study of eight men found a 6 percent increase in maximum weight lifted on the bench press by subjects who took creatine when compared with those who took placebo for 14 days. But, according to the authors, because of the small sample size, it's difficult to determine whether creatine enhances performance, and weight gain may be secondary to an increase in water retention in other studies. No serious side effects have been linked with the use of creatine supplements, which are legal in amateur and professional sports, but there have been two case reports of associated renal failure. Most alarming is a recent study that demonstrated that the majority of health club members sought information regarding creatine from popular magazines rather than a physician or dietician. Androstenedione Androstenedione, along with dehydroepiandrosterone (DHEA), is a precursor in the steroid synthesis pathway. It can be converted by the body to testosterone and, therefore, used to enhance athletic performance. Both supplements are taken as a "natural alternative" to anabolic steroids because nonprescription testosterone use is illegal. However, both androstenedione and DHEA have been banned by the International Olympic Committee, National College Athletic Association, and National Football League. Although information on study subjects and data were not presented, the initial German patent application reported that serum testosterone increased between 40 percent and 83 percent with 50 mg doses of androstenedione and between 111 percent and 237 percent with 100 mg doses. More recent studies have produced inconsistent results as to whether the supplement significantly increases serum testosterone levels, and there is no evidence of an ergogenic effect. When the supplement did increase testosterone levels, they were still within the limits of normal at a dose of 300 mg daily. However, many athletes ingest higher doses; advertisements recommend doses between 500 and 1,200 mg daily. Although no research on high-level usage has been conducted, adverse effects of testosterone above the upper limit of normal could include testicular atrophy, acne, behavior changes, and a possible increased risk of prostate cancer. Additionally, studies have found an increase in estrone and estradiol levels, which has been linked to an increased risk of breast cancer in women and pancreatic cancer in men, and a lowered high-density lipoprotein cholesterol concentration, which is associated with increased cardiovascular risk. Dehydroepiandrosterone (DHEA) Similar to androstenedione, manufacturers claim that DHEA aids in weight loss, increases muscle mass, and reduces the risk of cardiovascular disease and cancer with a recommended dosage of 30 to 90 mg daily. There have been inconsistent findings with respect to weight loss and no evidence of increase in testosterone or ergogenic effect. As with creatine and androstenedione, studies have involved a small number of subjects. In one study, five men received 1,600 mg daily of DHEA for 28 days. There was a 31 percent reduction in body fat and no increase in serum testosterone. Another study examined the effects of DHEA on an obese adolescent population. Subjects were given 40 mg of DHEA sublingually twice daily for eight weeks. Despite a significant increase in serum DHEA levels—as compared to subjects receiving placebo—testosterone levels were not increased and body weight and lipid levels did not change. Chromium An essential trace element found in meats, grain, mushrooms, wine, beer brewer's yeast, and oysters, chromium is said to decrease body fat and aid in promoting muscle growth. But, as with the other supplements, the studies have included a small number of subjects and produced conflicting results. Twenty college swimmers given 400 mg daily for 24 weeks experienced a 6.4 percent decrease in body fat and a 3.3 percent increase in lean body mass when compared with placebo, but a change in body composition or performance variables was not found in wrestlers given chromium supplements for 14 weeks. Because chromium and iron compete for binding on transferrin, it's possible for chromium to impair iron transport and contribute to iron deficiency anemia. In 36 men supplemented with chromium, there was a 24 percent decrease in transferrin saturation. Conclusion The authors suggest that further research, including studies with larger samples, be conducted to determine the merits and toxicity of these supplements. Most studies have included only a small number of subjects, and although there appear to be no serious side effects from the recommended doses, many patients exceed recommended doses. Comp Ther 2002; 28(2):148-154. Return to Top