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Feb. 8, 2000 (Washington) -- Androstenedione, a supplement sold in health food stores and taken by baseball great Mark McGwire, increased the amount of testosterone in men who took it for a week. That's according to a new study in the Journal of the American Medical Association, which was funded by Major League Baseball and the Major League Baseball Players Association. But that study is being criticized because the Harvard researchers did not investigate whether "andro" helped the men pump up their muscles. And some experts tell WebMD that not only is andro ineffective for this purpose, it is harmful and should be withdrawn from the market.

"Nobody cares that it raised testosterone levels," Charles E. Yesalis III, MPH, ScD, tells WebMD. "People who are buying this are not buying it for increasing their testosterone level ... they are buying it to increase their muscle mass and strength and enhance their physical appearance. The big question still remains. Are these changes of a magnitude to do that? If you asked me, does androstenedione work, I would say no."

Yesalis was not involved in this new study, but spoke out against andro last year after another study was published showing that andro raised levels of estrogen -- a female hormone -- in men who consumed it for eight weeks while involved in weight-training activities. In that study, the supplement had no effect on the men's muscle gain, compared to men who also trained and did not take andro. The study also showed that andro caused a drop in the HDL "good" cholesterol in these men.

This new study also showed increases in estrogen levels approaching those found in women, a fact that should sound alarms that andro could be bad news, especially for men and children, Yesalis says.

Andro, available without a prescription and not regulated by the FDA, received widespread publicity after it was revealed that McGwire, the home-run baseball record-holder, had used it. Although the substance is permitted in baseball, it is banned by the National Football League, the National Collegiate Athletic Association, and the International Olympic Committee.

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