Long-Term Use of Soy is Safe for Postmenopausal Women
Menopausal and postmenopausal women look for the effective remedy for menopause symptoms, and, therefore, they draw more and more attention to soy isoflavones. Recent studies has shown that soy had no clinically significant effect on endogenous hormone balance, i.e. its use is safe.
None postmenopausal women in those studies took hormone replacement therapy. They were randomly assigned to one of three low-fat, low-cholesterol diets incorporating a daily portion of either 40 g of test protein as milk casein, or 56 mg or 90 mg of soy isoflavones. The test protein was incorporated into baked products, beverages and soups as part of a standard menu.
In order to measure serum concentrations of several hormones, blood samples were collected at the beginning of the examination and after three and six months. As a result, scientists found no significant changes in serum estrogen, cortisol, dehydroepiandrosterone sulfate, or follicle stimulating hormone in any of the examined women. As for women that took the highest dose of soy isoflavones for more than six months, their circulating thyroid hormone levels were modestly increased, as well as their bone mineral density and higher HDL concentrations.