Androstenedione
Androstenedione--"andro" to its enthusiasts--is a pro-hormone, one of several compounds formed in the body during production of testosterone, the male hormone, a potent muscle-building steroid. To sports aficionados, it's the Mark McGwire drug, the supplement that the brawny Cardinals slugger took on the way to hitting 70 home runs in 1998.
"The first time I ever heard of these supplements was on TV, when Mark McGwire broke the home-run record," wrote Kevin, 14, responding to our questionnaire. "Soon after, I heard kids in school talking about it, wondering whether they should take them."
But andro flunked the two most rigorous studies of its efficacy. In both studies, volunteers took daily doses of andro while on a strength-training program; control groups followed the same training, but without taking andro.
One of the studies, published in 1999 in the Journal of the American Medical Association, involved young men ages 19 to 29; the other, published last November in the Archives of Internal Medicine, involved men 35 to 65. In both studies, those who didn't take andro gained just as much muscle and strength as those who took the supplement.
For the younger group, taking andro didn't even increase the average testosterone level. The older men experienced a temporary rise in testosterone, which subsided to normal levels by the end of the 12-week study. That's because taking the supplement for more than a few weeks disrupts the normal feedback that signals the body to produce its own sex hormones, says Craig Broeder, Ph.D., director of the human performance laboratory at East Tennessee State University and leader of the study involving the older men. "The body says 'I've got too much testosterone' and starts shutting off its own production of the hormone."
In both age groups, the androstenedione also produced unwelcome changes in blood-cholesterol levels, with an increase in the harmful kind and a decrease in the protective kind.
But perhaps the most disconcerting result of both studies was a marked increase in levels of the female hormone estrogen. In theory, that could lead to feminization, including the development of breast tissue, in long-term male users--a common side effect of prolonged steroid use.
Andro use in boys before or during puberty hasn't been studied formally. "We're just hypothesizing," Broeder says, "but based on everything we know, the minute a child took andro, his normal hormonal development would go awry." Among the possible results, depending on whether the andro ends up mainly as estrogen or testosterone: feminization, premature puberty, male-pattern baldness, and premature growth cessation.