Figure 5.

Metabolism fate of polyphenols by the human gut microbiota. In the mouth, the structure of polyphenols is broken down by enzymes, releasing the compounds from the food matrix. In the stomach, the polymeric polyphenols and their glycosidic bonds are hydrolyzed as the digestion process continues. Once they reach the small intestine, polyphenols undergo enzymatic deglycosylation, and absorption of some digested compounds (5–10%) takes place. The absorbed phenolic compounds enter the circulation and reach the liver, where they are metabolized further into smaller metabolites. At the same time, in the large intestine, gut microbiota hydrolyses unabsorbed polyphenols, making them available for absorption into the blood stream. Eventually, polyphenols metabolites are released from the body either through fecal matter or urine excretion.