Study Casts Dim Light on Androstenedione

Androstenedione, the dietary supplement used by slugger Mark McGwire, does nothing to boost men’s strength and instead may promote breast enlargement, heart disease and cancer, a study suggests.

The study, published in today’s Journal of the American Medical Association, compared the substance with a dummy pill in 20 men ages 19 to 29 during an eight-week weightlifting program.

In the study, androstenedione had no effect on testosterone levels in the blood, and no difference in strength could be found between the two groups of men, said Douglas S. King, an exercise biochemist at Iowa State University in Ames who led the research.

But the men who took the supplement showed significant declines in levels of the “good” cholesterol that helps prevent heart disease. The androstenedione also raised the men’s levels of the female hormone estrogen, King said.

Elevated levels of estrogen in men are known to promote breast enlargement and are also associated with a higher risk of cancer, he noted.

McGwire, who hit a record 70 home runs last year, had no comment on the findings. A furor erupted last year when The Associated Press reported that he used androstenedione.

Experts not involved in the new study praised it but said it leaves many questions unanswered.

“It’s the most comprehensive study on androstenedione that’s ever been done,” said Dr. Joel S. Finkelstein, an endocrinologist at Massachusetts General Hospital. But “what we really need are higher doses and larger groups of men studied.”