Soy isoflavone-specific biotransformation product S-equol in the colon: physiological functions, transformation mechanisms, and metabolic regulatory pathways

, and metabolic regulatory pathways affecting S-equol production. Advanced experimental designs and possible techniques in future research plan are also fully discussed. Furthermore, this review provides a fundamental basis for researchers in the field to understand individual differences in S-equol production, the efficiency of metabolic conversion of S-equol, and fermentation production of S-equol in vitro.