Gastrointestinal absorption and urinary excretion of trans-cinnamic and p-coumaric acids in rats

trans-Cinnamic acid (CIN) and p-coumaric acid (COU) are ingested by humans in their diet. While the metabolism and health benefits of CIN have been widely documented, little is known about its absorption sites, and there have been few studies dedicated to COU. The gastrointestinal sac technique demonstrated that CIN and COU are absorbed by all digestive organs in rats and partially transported via MCT-mediated carrier. Absorption was lowest in the stomach. Regardless of the organs that were studied, CIN was more efficiently absorbed than COU. After their individual oral administration to rats, CIN and COU were excreted in 0-24 h urine (0.3% and 23% of ingested CIN and COU, respectively). This suggests that COU was less metabolized than CIN. CIN and COU are absorbed across the digestive epithelium and subsequently interact with target tissues. Despite its lower gastrointestinal absorption, COU may have greater health benefits because it seems to be less metabolized than CIN.