genistein

Genistein is an isoflavone, a naturally occurring plant compound classified as a phytoestrogen because it can interact with human estrogen receptors. It is most abundant in soybeans and soy-derived products such as tofu, tempeh, and soy milk, but it is also present in smaller amounts in other legumes and grains. In plants genistein exists mainly as a glycoside; during digestion it is released and absorbed as the aglycone, with further metabolism in the liver and gut.

Chemically, genistein is 4',5,7-trihydroxyisoflavone, with an approximate molecular weight of 270 g/mol. It shows a higher affinity for estrogen receptor beta (ERβ) than for ERα, which is thought to contribute to tissue-selective estrogenic activity.

Biological effects observed in laboratory studies include inhibition of certain tyrosine kinases, modulation of cell signaling pathways such as MAPK and PI3K/Akt, antioxidant activity, and effects on cell growth and apoptosis in some cancer cell lines. In animals and humans, genistein and soy isoflavones have been investigated for potential effects on cancer risk, cardiovascular health, bone density, and menopausal symptoms, with results that are not yet conclusive.

Safety and intake: Dietary consumption of soy foods provides genistein at levels generally regarded as safe for most people. High-dose supplements raise concerns about estrogenic activity in hormone-sensitive tissues and may interact with thyroid function in iodine-deficient individuals or during pregnancy; clinical guidance is advised. Overall, evidence from clinical trials is mixed, and no definitive recommendations can be made regarding disease prevention.