The estrogen-like effects of red clover are due to its contents of isoflavones (biochanin A, formononetin, genistein, and daidzein), which are all considered phytoestrogens. Because of their structural similarity to estrogen, these isoflavones can bind to estrogen receptors in the body which may help reduce some of the symptoms of menopause that occur due to estrogen deficiency. There are two subtypes of estrogen receptors, estrogen receptor beta (ERβ) and estrogen receptor alpha (ERα), which are distributed differently throughout body tissues and have different actions. While estrogen binds both receptors equally, red clover isoflavones have a particular affinity for estrogen receptor β (ERβ) and only a weak affinity for estrogen receptor α (ERα), which means that the estrogenic effects of isoflavones will differ slightly from estrogen.[1][2]
Red clover also contains many other bioactive compounds, including the polyphenols coumaric acid, ferulic acid, and quercetin. While these contribute to the antioxidant and antimicrobial effects of red clover in vitro, it’s unclear what effects they might have when red clover is used as a supplement.[3]