CHICAGO -- Androstenedione, the supplement once used by Mark McGwire, really does raise testosterone above normal levels and could be hazardous, Harvard researchers say in a study financed by major league baseball.
A study last year found that the over-the-counter drug had no effect on testosterone levels or strength and instead may promote breast enlargement, heart disease and cancer.
The new study lasted just one week and did not measure whether andro can do what promoters have claimed -- make bigger muscles. But the researchers said andro could have that effect because it increases levels of the male hormone.
"If a patient of mine came to me and asked whether he should take androstenedione, I would caution against it simply because we don't know what the long-term effects are," said Dr. Benjamin Z. Leder, the Harvard University endocrinologist who led the study, published in Wednesday's Journal of the American Medical Association.
Side effects of elevated testosterone levels include acne, male pattern baldness and a decrease in "good" cholesterol, which could lead to heart disease. In women, high testosterone can also cause increased body hair, deepening of the voice and other male characteristics.
Androstenedione supplements are made of a naturally occurring steroid hormone the body uses to make testosterone. When supplements of testosterone are taken in high doses, they are known to have an anabolic effect -- increasing muscle size and strength.
Andro sales soared after McGwire acknowledged using it in 1998, the year he hit a record 70 home runs for the St. Louis Cardinals. He has since said he has stopped using it.
Andro is considered a dietary supplement, but the federal government is reviewing whether it should be reclassified as a steroid, which would remove it from store shelves and make it available by prescription only for legitimate medical uses.
It is banned by the Olympics, the NCAA, the NFL and the men's and women's tennis tours, but not by major league baseball. Baseball commissioner Bud Selig has been awaiting the Harvard study results to decide whether to take a stronger stance.
The study of 42 men found increases in testosterone levels when andro was taken for seven days in a single daily 300-milligram dose -- an amount that is probably far smaller than what athletes and bodybuilders use.
The subjects, ages 20 to 40, were divided into three groups and received either no androstenedione, 100 mg daily or 300 mg daily.
In the 300 mg group, testosterone levels in the blood increased by an average of 34 percent by the seventh day, though levels had returned to normal by the following day. The lower dose had no significant effect on testosterone levels, though levels of the female hormone estrogen increased substantially with both doses.
An eight-week Iowa State University study published last year in JAMA found no increased testosterone levels with 300 mg, but the dosages were given in 100 mg increments three times daily. The authors of that study and the new research said the dosage differences probably explain the new findings.
The Iowa study also found that andro increased levels of estrogen, which in men can result in breast enlargement and other feminizing effects.
The new study results "will be factored into the federal review of the proper classification" for andro, said Robert Housman, deputy director for strategic planning for White House drug adviser Barry McCaffrey.
Rob Manfred, executive vice president of labor and human resources for the baseball owners, said Tuesday there are no immediate plans for a policy change. "We've had the results for a very short period of time," he said.
Players' union official Gene Orza had no immediate comment.
Dr. Gary Wadler, an associate professor at New York University's medical school who has worked with McCaffrey, said the findings should come as no surprise. He advocates reclassifying androstenedione as a prescription drug.
"We now see what we all knew, just being in the business," he said.