Phenolic Acids Are Absorbed from the Rat Stomach with Different Absorption Rates

The intestinal absorption characteristics of phenolic acids (PAs) have been elucidated in terms of their affinity for the monocarboxylic acid transporter (MCT). Recently, the involvement of the stomach has been implicated in the absorption of polyphenols. The present work demonstrates that the gastric absorption efficiency of each PA is apparently different between various PAs. Various PAs with different affinities for MCT were administered (2.25 mumol) to rat stomach, and then the plasma concentration of the PA was measured. The plasma concentration of ferulic acid (FA) peaked 5 min after administration in the stomach. At 5 min after administration, the plasma concentration of each PA increased in the order: gallic acid = chlorogenic acid < caffeic acid < p-coumaric acid = FA. This order matches their respective affinity for MCT in Caco-2 cells, which we have demonstrated in previous studies. These results indicated that MCT might be involved in the gastric absorption of PAs, similar to the intestinal absorption.