Dehydroepiandrosterone (DHEA) is a steroid or hormone precursor, produced by the adrenal glands. It can be turned into testosterone, estrogen, and other chemicals we need. DHEA supplements, usually made from wild yams, are marketed as "the superhormone."

Claims, purported benefits: Builds muscle; staves off aging, cancer, and chronic diseases; eases menopausal symptoms and sexual dysfunction; cures Addison’s disease, atherosclerosis.

Evidence: DHEA has been extensively studied, both in lab animals and humans, but the research has not yet borne out any claims made by its manufacturers or promoters. A study in the Archives of General Psychiatry a few years ago did suggest that DHEA might be effective against mild depression. Studies continue around the world.

Bottom line: There’s no research to support the use of DHEA supplements at this time. Though DHEA production begins to decline at age 25 and falls to much lower levels by age 70, it does not necessarily follow that replacing it might slow or even reverse the aging process. DHEA has not been shown to reduce body fat, build muscle, improve sex drive, prevent Alzheimer’s or bone loss, or work against the many conditions for which it is touted. Side effects include fatigue and headache; in rare cases, women may develop facial hair growth or increased girth; men may experience breast enlargement or elevated blood pressure. Some experts think high levels of DHEA might promote breast or prostate cancer over time. DHEA interacts with many drugs, including tamoxifen (a breast cancer drug), Halcion (a sleeping pill), and insulin. Because DHEA is unregulated, you don’t know whether the pills even contain the amount of DHEA they claim.