Posted by Margie King
Soy has been touted as a lifesaver for menopausal women, with some claiming that its benefits include heart health, protection against bone loss and fewer episodes of hot flashes. But that may not be the case and in fact soy might make things worse.
Soy can be taken as a whole fresh food in the form of edamame, in a processed form as tofu, in a fermented form such as miso, tempeh and soy sauce, or in the form of supplements.
When it comes to supplements, however, research finds that soy isoflavone tablets do not appear to be associated with a reduction in bone loss or other menopausal symptoms in women within the first five years of menopause.
According to a report in the Archives of Internal Medicine, the beginning stages of menopause are often accompanied by rapid bone loss, hot flashes, vaginal dryness and sleep disturbances among other symptoms. Estrogen therapy with or without progesterone prevents most of these changes.
However, as a result of the Women’s Health Initiative findings suggesting that the overall risks of estrogen therapy outweigh the benefits, most menopausal women are increasingly seeking other alternatives, such as soy.
The Women’s Health Initiative study was halted early because of higher risks of breast cancer and cardiovascular disease in women using hormone replacement therapy.
In the University of Miami randomized controlled trial, study participants received either a placebo or a daily soy isoflavone dose of 200 mg, equivalent to approximately two times the amount that even the biggest soy fan would get through food sources in a typical Asian diet. Soy is often credited with the low rates of breast cancer and menopausal symptoms in Asian women.
During two years of follow-up, no significant differences were found between women in the soy isoflavone group and placebo group regarding changes in bone mineral density.
Menopausal symptoms were comparable between the two groups at the beginning and the end of the study, except for one surprising result: a significantly larger proportion of participants in the soy group experienced hot flashes and constipation compared with the control group.
The authors acknowledged that because of concerns regarding the risk of estrogens, a need exists for alternative interventions that could provide the beneficial effects of estrogens in bone and menopausal symptoms without the adverse effects on breast and cardiovascular health.
While there may be a need for some estrogen substitute to help midlife women deal with their symptoms and health risks, the authors concluded that in this study women in the first five years of menopause, on average, had low rates of bone loss, and that 200 mg of soy isoflavone tablets taken once daily does not prevent bone loss or reduce bone turnover or menopausal symptoms.
Silvina Levis, MD; Nancy Strickman-Stein, PhD; Parvin Ganjei-Azar, MD; Ping Xu, MPH; Daniel R. Doerge, PhD; Jeffrey Krischer, PhD Soy Isoflavones in the Prevention of Menopausal Bone Loss and Menopausal Symptoms A Randomized, Double-blind Trial Arch Intern Med. 2011;171(15):1363-1369.