Figure 1.

Ellagitannins and their hydrolysable derivative, ellagic acid, are natural polyphenols abundant in some fruits, nuts, and seeds. Ellagitannin is metabolized by gut microbiota into distinct types of urolithins that are further converted by large intestine enterocytes and the liver into conjugates. Both conjugated and unconjugated urolithins enter the blood circulation system and reach the body tissues. Besides accumulation in certain organs, urolithins are excreted in urine and feces [9]. Figure was adapted from [10,17].