Unfortunately, the amount of scientific evidence to support claims about soy is not as great as many believe. Two leading researchers in the United States have recently questioned the benefits of soy and the feeling that eating soy products can substitute for hormone replacement therapy. Dr. Lorraine Fitzpatrick from the Mayo clinic cautions about the belief that the two strategies - hormone replacement therapy and the addition of soy to the diet are equally effective. She questions the lack of scientific data to support the claims made for soy. Dr. Margo Woods at the Tufts University School of Medicine stated that in an experiment that she carried out where the benefits of soy were tested versus a placebo, there was no difference in the frequency or severity of hot flashes.
Soy contains plant steroids called isoflavones that structurally are related to estrogen.
This similarity in the chemical structure has led many people to conclude that soy isoflavones could play the same role in human metabolism as estrogen. This may be true, but if it is, the plant steroids may not be as powerful as natural human estrogen. Therefore, a long period of consuming soy products may be necessary in order to see any benefits. Epidemiological studies of Asian countries where the consumption of soy bean products is high and the incidence of hormone-dependent diseases such as breast cancer and ovarian cancer are used to support this argument. For many women adding foods that contain soy is a more natural way to treat the effects of menopause.