The Beneficial and Adverse Effects of Phytoestrogens

Abstract

The most well-known phytoestrogens (flavonoids, isoflavonoids, lignans, coumestans, stilbenes, and prenylflavonoids) are isoflavonoids, which are important active ingredients in medicinal and food plants. They are highly abundant in the Fabaceae family. More than 1,000 types of isoflavonoids have been isolated from nearly 300 kinds of plants, and more are being discovered through modern analytical methods. Glycosides O and C of isoflavonoids are poorly absorbed in the intestine. They are converted by bacterial esterases and/or β-glycosidase enzymes to aglycones, which are absorbed more efficiently. Their bioavailability shows significant differences due to variation in the intestinal microflora of various races. The compounds formed during their biotransformation are structurally similar to estrogens. In Traditional Chinese medicine, several herbs rich in phytoestrogens are used to prevent and cure various diseases, such as osteoporosis, cardiovascular diseases, diabetes mellitus, hypertension, hyperlipidemia, tumors, and inflammation; additionally, 185 herbs are used to treat menopausal symptoms. Some of these herbs can be used to alleviate the unpleasant symptoms of menopause and treat breast and prostate cancer. From a nutritional physiology perspective, the consumption of Glycine max and Vigna unguiculata should be emphasized. Soy has been consumed in China for about 5,000 years while it was introduced to Europe nearly 300 years ago. Soybean cultivation in Hungary dates back only 100 years. The assessment of the efficacy of phytoestrogens is unclear. Although several experimental and molecular biology studies have shown favorable results, studies on humans have not shown prominent therapeutic benefits. However, comparing and interpreting the findings of modern studies might elucidate the therapeutic utility of phytoestrogens.