Isoflavones are a sub-section of the plant isoflavonoids produced by members of the legume family, many of which function in mammals as plant oestrogens or phyto-oestrogens. These bond with oestrogen receptors in the body, where they may assist in enhancing oestrogen levels for menopausal women, counteracting symptoms such as hot flushes, and may help to improve cognitive function.
Soya isoflavones are the type most commonly found in human physiology, comprising two main sub-sectors, daidzein and genistein. Genistein is thought to work as a direct antioxidant, to counteract the cell-damaging effects of free radicals, as an anthelmintic to combat intestinal parasites, and as an anti-inflammatory helping to modulate the process of atherosclerosis.
Daidzein can be metabolised in the intestine to a metabolite with higher levels of oestrogenic activity than itself, called equol, or to other metabolites that have lower levels of activity, but equol is only produced by some 33% of westerners, influencing reliability as a dietary nutrient.
Postmenopausal women using dietary supplements of soya isoflavones have been found in many cases to retain a higher bone mass density, but the variation in results may be attributed to whether or not they can metabolise equol.