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MGH Research
Shows Androstenedione Can Raise Testosterone Levels
A study led by researchers from the Massachusetts General
Hospital (MGH) has found that 300 milligram (mg) doses of
androstenedione -- a dietary supplement used by some athletes
-- can raise blood testosterone levels in healthy young men.
The report, in the Feb. 9 issue of the Journal of the American
Medical Association also showed an increase in estrogen levels
with both 100 and 300 mg doses. It did not examine whether
taking androstenedione increases strength or muscle mass or
whether androstenedione has long-term side effects.
"A lot of people have been taking androstenedione under
the assumption that it will raise their testosterone levels,"
says Joel Finkelstein, MD, of the MGH Endocrine Unit, the
report's senior author. "This is the first study to show
that sufficient doses do raise serum testosterone. But we
now need to go on and study whether that increase actually
translates into changes in athletic performance or into negative
health effects."
Androstenedione is a steroid
hormone naturally produced in both men and women
Androstenedione produced in the body is converted to either
testosterone or to an estrogen. It is widely available as
a dietary supplement and primarily marketed to athletes and
bodybuilders in the belief that taking it will increase strength,
stamina and muscle mass. Currently classified as a dietary
supplement under the Dietary Supplement Health and Education
Act of 1994, androstenedione is sold over the counter. Its
use received wide public attention in 1998 when home run champion
Mark McGwire revealed that he had taken the supplement as
part of his training regimen.
The MGH-led study was designed only to test the claim that
taking oral androstenedione supplements would raise testosterone
levels. The research team -- led by Benjamin Leder, MD, also
of the MGH Endocrine Unit -- enrolled 42 healthy men aged
20 to 40 with no previous history of taking androstenedione,
steroids or any medication known to affect steroid levels.
Participants were divided randomly into three groups: 15 received
100 mg daily doses of androstenedione, 14 received 300 mg
doses of androstenedione, and 13 received no androstenedione.
During the seven-day study, blood tests taken at frequent
intervals after participants took the capsules measured levels
of four hormones: androstenedione, testosterone and the estrogens
estrone and estradiol.
While the 100 mg doses had no significant effect on testosterone
levels, the 300 mg doses increased testosterone levels by
an average of 34 percent. In one-third of those taking the
300 mg doses, testosterone levels exceeded the normal range
for men. Testosterone levels returned to normal within a day
of androstenedione administration. Estrogen levels also increased
in both the 100 and 300 mg groups: estrone increased 74 percent
at 100 mg and 196 percent at 300 mg, and estradiol increased
42 percent at 100 mg and 128 percent at 300 mg.
While this study examined only the direct effect of androstenedione
on hormone levels, the authors noted that long-term increases
in testosterone or estrogen can have serious side effects
in certain susceptible patient populations. Elevated testosterone
levels can lower levels of HDL (or "good") cholesterol
and can have masculinizing effects on women. Men with increased
estrogen levels can experience feminizing effects such as
the growth of breasts. Young people who have elevated levels
of either hormones could develop early puberty and a premature
cessation of bone growth, leading to shorter-than-normal adult
height.
The authors also note that the effects of androstenedione
were different for different individuals. Some participants
developed higher or lower hormone levels, suggesting that
certain people may be more or less sensitive to the hormonal
effects of androstenedione.
"We simply don't know what the long-term effects are
of taking a supplement that changes one's hormone levels,"
says Leder. "However, if a patient of mine asked whether
he should take this supplement, I would have to caution against
it."
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