What are Phytoestrogens Anyways?

Though phytoestrogens are a varied group of substances, they all share a chemical structure similar to estrogen. This structure allows them to bind weakly to estrogen receptors in the body and to exhibit weak estrogenic effects, although their activity is approximately only 2% as strong.

However, because of this low activity, phytoestrogens are considered to have a balancing action on estrogen effects. If estrogen levels are low, since phytoestrogens have some estrogenic activity, they will cause an increase in estrogen effect. If estrogen levels are high, since phytoestrogens bind to estrogen receptor binding sites, thereby competing with estrogen, there will be a decrease in estrogen effects.

A high intake of phytoestrogens is thought to explain, in part, why hot flashes and other menopausal symptoms rarely occur in cultures consuming a predominantly plant-based diet. Several phytoestrogens such as lignans and isoflavonoids are converted by intestinal bacteria to estrogenic compounds which decrease hot flashes, increase maturation of vaginal cells and help to inhibit osteoporosis.

However, this is a popular theory and though some information has been gathered with regard to the use of phytoestrogens therapeutically, more studies must be done before we fully understand their overall effect in the body. For example, the optimal dose of isoflavones has not been determined. A reasonable approach would be to take a daily level of isoflavones that does not exceed the amount consumed in ethnic diets that contain high amounts of isoflavones. It appears that this amount is somewhere between 50-150 mg of isoflavones per day for adults. When it comes to taking concentrated dietary soy supplements, we should be aware that a different biological activity and effect may be possible.