Hot flushes, night sweats, vaginal dryness and decreased sexual desire are classic symptoms of menopause that improve when affected women are treated with hormone replacement therapy, or HRT. Usually a combination of estrogen and progestin, HRT was once thought to not only relieve menopausal symptoms, but to protect women from breast cancer as well. However, in 2003 a large clinical trial stopped when it discovered that HRT actually increased a woman's chances of developing breast cancer and heart disease. Since that time, women have sought alternatives to HRT.
Phytoestrogens
Dozens of plants contain phytoestrogens, compounds that exert estrogen-like effects when you consume them. Many experts, including Dr. Duane Townsend, author of "A Maverick of Medicine Speaks to Women," believe that phytoestrogens are safe, effective alternatives to HRT. According to Townsend, phytoestrogens act like weak estrogens in your body, binding to the same receptors that your own circulating estrogens do. This effectively stimulates these receptors and lessens menopausal symptoms without causing the undesirable side effects of HRT.
Soy Isoflavones
Because the incidence of breast cancer and heart disease is lower in populations where soy is regularly consumed, soy isoflavones, a special class of phytoestrogens, have garnered scientists' attention as a potential replacement for HRT. Specifically, genistein, one of soy's primary isoflavones, has been the subject of dozens of scientific studies and clinical trials to evaluate both its effectiveness for treating menopausal symptoms and its safety in women who are at risk for breast cancer and other estrogen-dependent malignancies.
Benefits and Safety
A two-year study involving nearly 400 women, published in "Menopause" in 2009, demonstrated that genistein reduced the number of hot flushes by over 50 percent after a year of therapy. Notably, this benefit was achieved without any evidence of endometrial thickening. The endometrium is the inner lining of the uterus that thickens when stimulated by estrogen, and long-term estrogen stimulation can lead to uterine cancer. Other studies have shown similar results, but not everyone agrees that genistein is safe for all menopausal women.
Breast Cancer
One of the primary concerns surrounding the consumption of soy products is whether or not they increase the risk for breast cancer. A 2010 review in "The Journal of Nutrition" reported that moderate consumption of soy products does not increase the risk for recurrence in Western women who have been diagnosed with breast cancer, and that Asian women with breast cancer who continue to consume soy actually have better survival rates. However, these benefits may only accrue after years of soy consumption. Similarly, a five-year study published in the "Canadian Medical Association Journal" showed a lower risk of breast cancer recurrence among soy-consuming women whose tumors were estrogen- and progesterone-receptor-positive.
Controversy
Not all scientific evidence is so supportive of soy's benefits and safety. A 2010 study in "Clinical and Experimental Metastasis" raised the possibility that consumption of soy foods could increase the spread of existing breast cancers, and one earlier study showed that low levels of genistein could interfere with the ability of immune cells to destroy breast cancer cells. If you want to try soy products for menopausal symptoms, check with your physician first.
References
- PubMed.gov: HABITS (hormonal replacement therapy after breast cancer -- is it safe?), a randomized comparison: trial stopped
- "A Maverick of Medicine Speaks to Women"; Duane Townsend, M.D., and Rita Elkins, M.H.; 2003
- PubMed.gov: Effects of the phytoestrogen genistein on hot flushes, endometrium, and vaginal epithelium in postmenopausal women: a 2-year randomized, double-blind, placebo-controlled study
- PubMed.gov: Is soy consumption good or bad for the breast?
- CMAJ: Effect of soy isoflavones on breast cancer recurrence and death for patients receiving adjuvant endocrine therapy
- PubMed.gov: Individual and combined soy isoflavones exert differential effects on metastatic cancer progression
