Does equol production determine soy endocrine effects?

Isoflavones, a group of phytoestrogens, are selective oestrogen receptor (ER) modulators. They may positively impact endocrine-related conditions but the current evidence is sparse. Equol, a non-steroidal oestrogen, is produced by the metabolism of the isoflavone daidzein by intestinal bacteria. In Western countries, 30-50% of individuals metabolize daidzein into equol and are known as equol producers. Equol production may be the source of benefit from isoflavones in endocrine disease.