Urolithin

[1] They are produced in the gut, and found in the urine in the form of urolithin B glucuronide after absorption of ellagitannins-containing foods, such as pomegranate.

[2] During intestinal metabolism by bacteria, ellagitannins and punicalagins are converted to urolithins, which have unknown biological activity in vivo.

[medical citation needed] Ellagitannins exhibit low bioavailability and are transformed in the gut to ellagic acid and its microbiota metabolites.

[medical citation needed] Urolithins are found in plasma mostly as glucuronides at low concentrations.

Individuals producing urolithins show a much higher abundance of the Clostridium leptum group of Firmicutes phylum than Bacteroides or Prevotella.