Four common dietary polyphenols underwent in vitro human gastrointestinal digestion.
Colonic microbial biotransformation decreased the concentration of pure polyphenolic compounds.
Microbial metabolites included dihydrocaffeic, phenylpropionic, phenylacetic and vanillic acids.
20">Polyphenols increased antioxidant capacity and colonic short chain fatty acids (SCFA) concentrations.
25">Microbial metabolites and SCFA showed differing profiles in each of the colonic compartments.