Bioactive isoflavones in functional foods: the importance of gut microflora on bioavailability.

Isoflavones present in soy may have risk and benefits to human health. Human gut microflora have been shown to exert metabolic activities on isoflavones, which influences bioavailability and bioactivity. Absorption of isoflavones is likely to occur in the small intestine where there is a diverse range of microfloral species able to hydrolyze conjugated isoflavones, releasing the bioactive aglycone for absorption or further metabolism and reconjugation. The identification of gut microbes that metabolize isoflavone aglycones is not well established. Such information may lead to a better understanding of the bioavailability of isoflavones in functional foods.