Influence of phytoestrogens on humans and animals.

摘要

Phytoestrogens are compounds found in plants with oestrogenic activity. Their chemical structure is similar to estradiol. The three main classes of phytoestrogens are isoflavones, lignans and coumestans. The major bioactive isoflavones are genistein and daidzein. Phytoestrogens are widely present in plants regularly consumed by animals and humans: e.g. oats, barley, wheat, corn and clover. The most significant sources of isoflavones are soyabeans and soya foods. Lignans are present in plant foods; mainly in flaxseed, but also in grains, fruit and vegetables. Phytoestrogens are compounds which exhibit oestrogenic activity. This activity was first recognized in sheep and is known as "Clover Disease". In these animals, phytoestrogens cause reproductive disorders or even infertility. The feeding of female rats with a soya-rich diet induces an increase in uterine weight. Vaginal modifications have also been observed. Phytoestrogens also exhibit anticarcinogenic activity. Animal studies have demonstrated reduced cancer development with soyabean consumption. Genistein and other phytoestrogens have a beneficial role in obesity and diabetes mellitus. These compounds cause slight decreases in insulin, total cholesterol and triglyceride contents. Phytoestrogens also increase the amount of cholesterol in high density lipoproteins (HDL) and decrease the amount of very low density lipoprotein (VLDL) and low density lipoprotein (LDL) cholesterol, and can reduce risk of cardiovascular diseases. Experiments performed on animals demonstrate that genistein and daidzein clearly inhibit lipogenesis and enhance lipolysis. Phytoestrogens also have a special role in the prevention of osteoporosis..