DHEA, or dehydroepiandrosterone, is a hormone that breaks down into various sex hormones, including testosterone, which helps build muscle. Researchers report in the March issue of Fertility and Sterility (vol 81, no 5) however, that the testosterone created from DHEA does not stay long in the blood, but instead, quickly breaks down into other hormones associated with prostate gland growth.
"Our study showed that taking DHEA did not increase testosterone levels, but it did increase byproduct hormones that are potentially bad for the prostate," said Rebecca Z. Sokol, professor of obstetrics and gynecology and medicine at the Keck School and the paper's senior author. "Not only are users not getting the testosterone, but they may be getting something harmful in the process."
Sokol said that interest in the steroid supplement DHEA rose after baseball's former slugger Mark McGwire said he used androstenedione, or 'andro', a similar muscle-pumping pill to help achieve his record-setting home-run tally in 1998. DHEA is readily sold in health food stores and nutrition centers in 25mg and 50mg doses, though many athletes take 200 mg or more at a time.
Sokol and colleagues tested DHEA in a randomized, double-blind placebo-controlled study of 12 healthy men aged between 18 and 42. It was the first such study to compare an intermediate dosage of DHEA and a relatively high dosage of DHEA in non-elderly men.
Every day for six months, each man took either 50 mg DHEA, 200 mg DHEA or a sugar pill. Researchers tested blood for levels of various hormones (DHEA, DHEA sulfate, androstenedione, testosterone, estradiol, dihydrotestosterone, and 5-alpha-androstane-3-alpha-17beta-diol glucoronide, or ADG for short). They also performed numerous medical tests and monitored men's prostate size through digital exams.
The team found that over six months, taking DHEA regularly - whatever the dose - increased the circulating level of DHEA, DHEA sulfate and ADG circulating in the men's blood. Sokol and her colleagues had expected to see levels of testosterone rise, but they stayed the same. Levels of androstenedione, estradiol and dihydrotestosterone circulating in the blood also did not change significantly.
"When the body gets an excess of DHEA, it appears to preferentially turn the DHEA into testosterone, then DHT and then ADG," Sokol explains. Testosterone may quickly break down into DHT, which quickly breaks down into the more stable hormone ADG. Elevated levels of that hormone then remain circulating in the blood.
Other studies have indicated that ADG is a growth factor for the prostate, and may prompt benign prostatic hypertrophy, the prostate enlargement commonly seen as men age, she says. When they conducted digital exams, the Keck School researchers did not find signs of enlarged prostate glands, Sokol says, but the time-span of the study may have been too brief to detect enlargement. Digital examination also may not detect changes in size as well as other techniques such as ultrasound.
Researchers are unsure about potential effects of elevated DHEA and DHEA sulfate in the blood. "It is possible that DHEA itself enhances muscle development, but that's not been documented," Sokol said. DHEA is normally produced by the adrenal gland.
Sokol notes that further study is needed on the specific effects of DHEA and similar hormones, which are classified as nutritional supplements and unregulated by the United States Food and Drug Administration.
"Young kids of high school and college age are taking this drug because they think it's going to enhance their athletic performance," she said. "But little is known about what the drug really does."