Don’t believe the hype. These supplements might not do any good, and they could in fact do some harm.

Ginkgo biloba: Once thought to improve memory, this herb has been shown to be about as effective as a placebo.
Human growth hormone: “It may increase muscle mass,” says Roger McCarter, Ph.D., chair of the scientific-review committee for the American Federation for Aging Research, “but it may also be a stimulator of cancer-tumor growth.”
DHEA: Levels of this hormone fall off with age. The results are mixed on whether DHEA can help build muscle in older people. Experts caution that DHEA supplements can cause overproduction of estrogen and testosterone, high levels of which play a role in breast and prostate cancers.
Ginseng: Several studies have shown that daily doses of this herb modestly enhance mental performance. But further research is needed to determine whether it can help prevent cancer, lower blood pressure, or boost stamina.