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Phytoestrogens (Soy) Show Similar Benefits of Hormone Replacement Therapy And Help May Prevent Breast Cancer (dateline May 3, 2000)

A new study published in the May 2000 issue of the Journal of the American College of Cardiology finds that phytoestrogens (natural chemicals found in many plants) provide women with many of the same benefits as hormone replacement therapy (HRT) without increasing the risk of breast or uterine cancers. In addition to treating hot flashes and other menopausal symptoms, research has shown that phytoestrogens may help prevent breast cancer, heart disease, and osteoporosis (a degenerative bone disease). Phytoestrogens are found in soybeans, flaxseeds, black cohosh, alfalfa spouts, and other plants.

Researchers believe that phytoestrogens may provide multiple benefits to women because they help balance hormone levels in the body. A lack of the hormone estrogen has been shown to increase the risk for osteoporosis and heart disease. However, too much estrogen may contribute to breast or uterine cancer because some cancer cells depend on estrogen for survival.

Researchers say phytoestrogens (also called isoflavones) could be especially useful because they can act like weak estrogens when necessary, providing hormonal protection against menopausal symptoms (hot flashes, vaginal dryness, etc.), heart disease, and osteoporosis. On the other hand, phytoestrogens can also block estrogen from reaching estrogen receptors in cells, protecting the body from breast and uterine cancer.

In a study conducted at the Stanford University Medical Center in California, women who were given a soy-based diet lowered their total cholesterol levels by 9% and LDL cholesterol levels ("bad cholesterol") by 13% compared to women who did not include soy in their diets. Phytoestrogens were also shown to protect against menopausal symptoms, osteoporosis, and decrease the risk for breast cancer.

Research on phytoestrogens is relatively new, though. According to Lynette Wroblewski Lissin, MD and John P. Cooke, MD, phytoestrogens seem to provide several benefits, including protecting high risk patients from developing heart disease. However, further studies on phytoestrogens need to be conducted. Presently, Dr. Lissin and Cooke believe women at high risk of cardiovascular disease may benefit from a soy diet, especially if they do not have a family or personal history of breast or uterine cancer.

The average amount of soy recommended for women to help protect against breast cancer is 35 grams per day—also the average amount Asian women consume per day. 60 grams is the maximum amount of soy used in clinical trials involving breast cancer patients. Products rich in phytoestrogens include soy milk, tofu, roasted soy nuts, soy protein powders, and tempeh. Not all soy products contain phytoestrogens (also called isoflavones).

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