Health benefits of phytoestrogens in postmenopausal women

This review includes recent clinical evidence that phytoestrogens relieve menopausal symptoms and prevent cardiovascular diseases and osteoporosis in postmenopausal women. Soy isoflavones have been the most extensively investigated. Although the effects are not consistent and whether the effective component is soy protein or an isoflavone is still controversial, some studies have indicated their effects on reducing hot flash symptoms and blood lipids, improving bone mass, changing sex hormone metabolites, and increasing sex hormone-binding globulin levels, which might confer an anti-breast cancer effect. Moreover, they do not cause stimulation of the endometrium. A few studies have focused on flaxseed, yams and on indole-3-carbinol of cruciferous vegetables. All of them switch the metabolism of estrone to a less- carcinogenic pathway. Flaxseed lowers blood lipids but has no effect on bone mass. The inconsistent results of phytoestrogen research might have resulted from variations in the bioavailabilities of phytoestrogens among individuals. Although the relative potencies of phytoestrogens as compared to estradiol are small, they do not increase the risks of breast cancer and cardiovascular diseases as does the traditional estrogen therapy. Since the phytoestrogenic components in most foods are not well known, we suggest consuming a variety of phytoestrogen-containing natural foods to hopefully obtain additive effects.