Performance-Enhancing Supplements Not for Everyone
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
"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
While much of the public attention has been focused on
androstenedione, other performance- enhancing supplements are also gaining
popularity, says Jeffrey Stout, PhD, assistant professor of exercise science
and director of the human performance laboratory at Creighton University in
Omaha, Neb. Chief among these other supplements is creatine. "The body
synthesizes creatine, and it is stored in muscles. But, we have found that
supplementation can increase creatine levels," he says.