“Little is known about the long-term safety of [sports supplements] in adults, and even less about their effect on youngsters,” warns Consumer Reports in its June 2001 issue.

Androstenedione, the supplement Mark McGwire took on the way to hitting 70 home runs in 1998 flunked the two most rigorous studies of its efficacy in building muscle and strength. Both studies showed it produced increased levels of the female hormone estrogen and unwelcome changes in blood cholesterol.

Supplemental use of creatine, an amino acid, has been shown in a few well-designed studies to enhance performance requiring brief, intense bursts of strength. But muscle cramping and exacerbation of existing kidney problems among creatine users have appeared in the medical literature.

Ephedra (ma huang) is an herbal product containing several stimulants including ephedrine and pseudoephedrine. Almost all ephedra products contain at least one other stimulant such as caffeine from the herb guarana. Ephedra has been shown to produce heart palpitations at levels that produce moderate weight loss.

Of 140 adverse event reports to the FDA related to ephedra alkaloids from June 1997 to March 1999, 87 of the events were “definitiely,” “probably,” or “possibly” caused by the ephedra. Ten of the these 87 events resulted in death and 13 produced permanent disability. [New England d Medicine 343:1833–1838, 2001.]

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