In 1997, oral DHEA (dehydroepiandrosterone) was reportedly the fastest-selling product in health food stores. Millions of Americans are probably still taking medically unsupervised DHEA supplements in the belief that DHEA may have anti-aging properties. It may, but is it safe? On the basis of what's known of the relation between DHEA and insulin-like growth factor-I (IGF-I), it might not be.

In a recent issue of Science, Chan and coworkers [1] reported that high endogenous plasma IGF-I levels may represent a major risk factor for prostate cancer. In their series, men in the highest quartile of IGF-I levels had a relative risk for prostate cancer of 4.3 compared with men in the lowest IGF-I quartile; in men older than 60 years of age, the relative risk was 7.9. Along with growth hormone, DHEA is known to increase serum IGF-I levels. In a clinical study of 30 patients aged 40 to 70 years who were receiving 50 mg of DHEA daily for 3 months, Morales and colleagues [2] found that this hormone increased serum IGF-I levels in men from a mean of 151.3 ± 10.2 ng/mL to 180.1 ± 15.4 ng/mL and increased the bioavailability of IGF-I (ratio of IGF-I to IGF-binding protein type 1) by 52% ± 15.9%. In our study of 10 men aged 50 to 68 years given 25 mg of micronized DHEA for 3 months, mean IGF-I levels increased from 175 ± 11.8 ng/mL to 247 ± 16.2 ng/mL. Neither serum testosterone nor prostate-specific antigen levels changed significantly in any participant during this period.

In women, but not in men, daily DHEA supplements in the dose range of 25 to 50 mg increase, and in many cases double, the level of serum testosterone [2]. Thus, women who take too much of this hormone or who are unduly sensitive to its effects can develop such unpleasant androgenic side effects as acne, hirsutism, irregular menses, and male-pattern hair loss.

Chan and associates concluded their report by warning that "the administration of [growth hormone] or IGF-I over long periods, as proposed for elderly men to delay the effects of aging, may increase the risk of prostate cancer." If the proposed link between high blood levels of IGF-I and risk for prostate cancer can be confirmed, the same warning may apply to the unsupervised and possibly excessive ingestion of DHEA. Moreover, the following recommendations make sense: 1) The availability of oral DHEA should be under supervision of the U.S. Food and Drug Administration and 2) for men receiving DHEA supplements, serum levels of DHEA, prostate-specific antigen, and IGF-I should be periodically measured and the minimally effective dose prescribed.