Q. Lately I've been hearing a lot about bio-identical natural hormone replacement therapy for women. What is it? Is it safer than conventional hormones? And why would women want to take it?

A. For at least 20 years, naturopathic physicians have prescribed bio-identical natural hormones to help women with a number of different hormone imbalances. "Bio-identical" means that the chemical structure of the hormones is exactly like the hormones that women make in their own bodies; "natural" means that the hormones come from a natural source, such as a plant or an animal.

Many physicians now recommend bio-identical natural hormone replacement therapy rather than synthetic non-bio-identical hormones for a number of reasons. Bio-identical natural hormone replacement therapy appears to be safer than synthetic hormones, such as those found in many prescription hormone regimes, including Provera and Premarin. (Premarin could be considered "natural" by some because it is derived from the urine of pregnant horses, but it is not bio-identical because it contains many different hormones — including horse hormones).

It is important to note that in 2002, the landmark hormone study called The Women's Health Initiative was abruptly halted because it was found that Premarin and Provera increased the risk of breast cancer, heart disease and strokes. A 2009 article by Dr. Kent Holtorf published in the journal Postgraduate Medicine stated, "Physiological data and clinical outcomes demonstrate that bio-identical hormones are associated with lower risks, including the risk of breast cancer and cardiovascular disease, and are more efficacious than their synthetic and animal-derived counterparts. Until evidence is found to the contrary, bio-identical hormones remain the preferred method of hormone replacement therapy. Further randomized controlled trials are needed to delineate these differences more clearly."

Why would women want to take bio-identical natural hormone replacement therapy? As a naturopathic doctor specializing in women's health, and with many of my patients going through mid-life changes associated with perimenopause, I have found that using very low-dose natural bio-identical hormones can enhance quality of life and improve libido. Natural hormones such as progesterone can also help women who suffer from PMS, heavy menstrual periods and insomnia associated with low progesterone. Low-dose estrogen can help reduce midlife changes including hot flashes, night sweats, mood changes and vaginal dryness.

There are contraindications to using bio-identical natural hormone replacement therapy; for example, women who have had an estrogen- or progesterone-related cancer, or a history of blood clots, should not use any hormones. Every woman should be carefully evaluated by a doctor before beginning therapy, and she will need to have an annual pelvic exam, including a pap smear, and mammogram.

Naturopathic physician and licensed acupuncturist Laurie Steelsmith is the author of "Natural Choices for Women's Health" (Random House). Contact her and read her columns at www.DrSteelsmith.com. This column is for information only; consult your health provider for medical advice.