(S)-equol (4′,7-isoflavandiol) – also called 5-hydroxy-equol – is produced by intestinal probiotics after they consume the isoflavones daidzein and genistein we eat. Some have proposed that S-equol only comes from daidzein but recent research clearly indicates that certain probiotics will produce S-equol from genistein. Tyrosine metabolite.
Equol is a nonsteroidal estrogen, and a compound that can exist in two enantiomers, (S)-equol and (R)-equol. Only (S)-equol is produced in humans and animals with the ability to produce equol after soy isoflavone consumption, and is characterized as an isoflavan and an inhibitor of steroid sulfotransferases such as SULT1A1, SULT1E1. (S)-equol is a nonsteroidal, selective agonist of ERβ (estrogen receptor beta), with 13-fold selectivity for ERβ over ERα.