Phytoestrogens for Menopause:What does it all Mean?

This isn't easy for me to admit. After scouring the Internet and textbooks for the latest research on phytoestrogens for menopause, I'm stumped as to what it all means and what to recommend to women considering the use of phytoestrogens for the relief of menopausal symptoms. Quite frankly, I discovered that many of the studies and articles conflicted with one another. By the time I was finished, I didn't know which ones to believe. Nevertheless, let's take a look at the data and see what we can sort out.

Phytoestrogens are chemical substances found naturally in plants which are biologically related to human estrogen. There are phytoestrogens in soybeans, clover, alfalfa sprouts and flaxseeds, with soybeans being the most commonly-used source in the human diet. Soy protein is found in tofu, soy milk, soy nuts, "veggie" burgers and in some supplements in tablet form. It is the isoflavones in soy which give it phytoestrogenic properties.

What are phytoestrogens good for? Unfortunately, it depends on what kind of research you're looking at. Cultural studies contend that soy is good for the prevention of breast cancer and for the reduction of hot flashes in women because Asian women, who consume a fair amount of soy in their diet, have a reduced risk for both conditions as compared to American women. The problem as I see it, though, is that soy isn't the only difference in our diets (not to mention our genetic make up, either) and that the consumption of soy is might be unrelated to why Asian women have a better risk profile than we do.

Some clinical studies in menopausal women showed a reduction in hot flashes in those who consumed soy isoflavones as compared to those who took a placebo. Other studies showed no statistical difference. I don't know how to interpret studies which differ like this.

I was especially intrigued by the biochemical studies on phytoestrogens. It seems from these studies that plant estrogens do bind to estrogen receptors in the human body but to a degree that is 100-fold less than human estrogen. The results are split, however, on whether plant estrogen, once bound to an estrogen receptor, turns ON the receptor (therefore having estrogenic properties) or turns OFF the receptor (thereby having anti-estrogenic properties).

Why is this important? Because if soy protein has positive estrogenic properties, I'm not going to be too excited about recommending it to women who are at risk for developing estrogen-dependent cancers like breast cancer. Anything that acts like an estrogen theoretically could feed such cancers, stimulating their growth. On the other hand, studies in animals and in cancer cell cultures have shown that soy phytoestrogens actually inhibit the growth of such cancers rather than stimulate them.