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June 5, 2000 (Indianapolis) -- Fitness in a bottle has been a popular concept since the days of musclemen kicking sand in the faces of 98-pound weaklings. But, when Mark McGwire admitted to taking a performance-enhancing supplement while on his way to breaking Roger Maris' home run record, these pills and powders began making their way into gym bags in Little League lockers and major league clubhouses. That, says Harvard University's Joel Finklestein, MD, may be bad news.

Finklestein, an associate professor of medicine at Harvard, says that androstenedione -- McGwire's supplement of choice -- at doses of 300 mg "causes whopping increases" in the levels of the male hormone testosterone in the blood.

That testosterone booster is what may increase muscle mass, according to Shalendar Bhasin, MD, professor of medicine at Charles Drew University in Los Angeles. Bhasin and Finklestein joined other experts at the 47th Annual Meeting of the American College of Sports Medicine in a symposium discussing the effects of performance-enhancing supplements.

Finklestein and colleagues from Harvard recently studied the blood taken from healthy men given either 100 mg or 300 mg of androstenedione. At 100 mg, he says, there is no effect on blood levels of testosterone. But, even at the lower dose, androstenedione does affect the levels of estrone and estradiol. Both estrone and estradiol are potent forms of the female sex hormone estrogen, which is normally present only in minute quantities in men.

"Estradiol is so high it looks like these men are getting ready to ovulate," Finklestein says.

Androstenedione is purified from plant sources and so is not controlled as a drug by the FDA, says Finklestein. Asked if he had any recommendations about its use, he tells WebMD, "I'm very cautious about recommendations. But, in general, I don't think that people should be taking substances that have not be subjected to rigorous tests of both toxicity and efficacy. And, because this substance has [a masculinizing] and estrogenic effect, I don't think it's appropriate for women and children."

Olympic officials are also worried about the use of androstenedione and in 1998 added it to the list of substances banned in Olympic athletes, says Donald Catlin, MD, professor of medicine at UCLA. Caitlin is director of the UCLA U.S. Olympic test lab. He says that both the NCAA and the NFL took a cue from the Olympics and also banned the supplement. Professional baseball and professional basketball have not yet taken action.

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