Bioavailability and metabolism of coffee chlorogenic acids in humans

Abstract

Chlorogenic acids are coffee bioactives that are becoming of great interest for their health promoting effects. However, human bioavailability of these compounds is not fully understood. We investigated plasma appearance of coffee chlorogenic (CGAs) and phenolic (PAs) acids after ingestion of coffee by healthy volunteers. Two groups of metabolites appeared over the 24h after coffee ingestion where plasma CGAs and PAs were measured after enzymatic treatment. Caffeoyl quinic, feruloyl quinic, caffeic, ferulic (FA) and isoferulic acid appeared rapidly with mean Cmax less than 2 hours after ingestion, indicative of intestinal absorption. Dihydrocaffeic and dihydroferulic acid peaked between 10 and 12h, which might suggest colonic metabolism and absorption. While colonic metabolites were present in high amounts (Cmax > 1μM), other PAs acids were present in lesser quantities (Cmax < 500nM). CGAs were present in low quantities (Cmax < 100nM), while di-caffeoylquinic acids were only detected in trace amounts. Surprisingly, FA and isoFA showed strong biphasic plasmatic curve while the methylated form of FA (dimethoxycaffeic acid) did not. Taken together, these data show the complexity of absorption and metabolism of coffee polyphenols in healthy humans. It also highlights the importance of this beverage as a significant dietary source of bioactive compounds.