Some of the anti aging hormones normally made by your body are now available in bottles at your local health food store. And while the government classifies these "bottled hormones" as dietary supplements, some experts say that they shouldn't be.

"These products are powerful substances and should be viewed as drugs," says Alan R. Gaby, M.D., professor of nutrition at Bastyr University in Kenmore, Washington. "They have potential for great benefit, but they can also cause significant harm."

One example is DHEA (dehydroepiandrosterone). In animal studies, this male hormone (which a woman's body makes, too) appears to boost immunity and help protect against diabetes, heart disease, and even cancer.

Here's the problem. Our bodies convert DHEA into estrogen and testosterone. So if even a small amount is converted to estrogen in a woman with a family history of breast cancer, she may be increasing her risk of developing the disease, says Dr. Gaby.

Pregnenolone, the precursor to DHEA, is another bottled hormone that's flying off the shelves. But clinical research on this hormone is sparse. "There's an animal study that suggests that it improves memory, and that's about it," says Dr. Gaby.

In the body, pregnenolone may be converted into DHEA, increasing our bodies' amounts of estrogen and testosterone. There are potential risks in using pregnenolone, says Dr. Gaby. It hasn't been used long enough to determine if it is safe.

The bottom line: Don't self prescribe hormone supplements, says Dr. Gaby. Consult a doctor, who will advise you if hormone supplements are appropriate, prescribe them at the appropriate dosage (if necessary), and monitor your progress.