December 29, 2010
Soy Supplements Deemed OK For Long-Term Use
Studies suggest that soy supplements taken regularly by menopausal women don't put them at a higher risk for breast cancer or any other health issues.
The soybean (Glycine max) belongs to the legume family, whose members include peas, beans, and peanuts, as well as clovers and alders. Legumes feature phytonutrients that lend some unique benefits to women in menopause. The soybean in especially rich in isoflavones, the most widely studied class of phytonutrients. Of the three main types of soybean isoflavones, the ones found most effective for menopause symptoms relief are genistein and daidzein. A third isoflavone, glycitein, is also being studied to determine its health benefits.
In addition to the healing power of isoflavones, soy is also high in antioxidants, omega-3's, and protein. Plus, it's low on the glycemic index.
Dr. Francene M. Steinberg of the University of California, Davis, noted in the American Journal of Clinical Nutrition that while there is little evidence from current research that the supplements can cause harm, the researchers add, they allow women to consume up to four times the amount of isoflavones contained in a typical Asian diet.
However, very few studies have looked at the long-term safety of consuming too much soy.
To investigate, the researchers evaluated data from the Osteoporosis Prevention Using Soy (OPUS) Study. A previous analysis of the results found no effect of soy supplements on the density of breast tissue, one indicator of breast cancer risk. In the current study, the researchers looked at blood tests, health exams and adverse events to further examine the risks of soy.
A total of 403 women completed the study, including 134 women taking placebo, 135 women taking 80-milligram soy tablets, and 134 taking 120-milligram tablets.
Overall, no big health issues became apparent in the participants except for one woman in the 120-milligram soy group who developed breast cancer after taking the supplement for 14 months, while another woman in the 80-milligram soy group developed uterine cancer.
However, the researchers note, the rate of both cancers in the study was lower than would have been expected in the population of menopausal women as a whole.
A researcher concluded the findings support the safety of soy hypocotyl isoflavone supplementation over a 2-year period.
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