Biliary excretion of quercetin metabolites in conscious rats was biphasic, a high peak within 3 h and a lower peak for next 6 h, after duodenal administration of soluble quercetin glycosides. We also found much higher biliary excretion of quercetin metabolites than urinary excretion on feeding a quercetin glycoside diet. These results suggest high levels of enterohepatic circulation of quercetin metabolites.
