Pharmacokinetics of black tea-derived phenolic acids in plasma

Little is known about the pharmacokinetics of black tea metabolically-derived phenolic acids (PAs). This knowledge is required to better understand their putative role in human health. Plasma concentrations of 18 PAs were measured after intake of 2650 mg black tea extract, combined with a 50 mg dose of three selected mass-labelled PAs. Levels of 15 PAs remained constant at low-µmol/L range. In contrast, those of 4-O-methylgallic acid, gallic acid, and hippuric acid peaked at up to 6.5 µmol/L after 1.3 to 8.8 h. Absorption and elimination half-lives of the mass-labelled PAs ranged from 0.35 to 1.24 h. A wide range of PAs were accurately quantified in plasma after black tea extract intake. Their mostly constant plasma concentrations may be due to slow formation and fast elimination, as indicated by the fast pharmacokinetics of mass-labelled PAs. These findings support the physiological significance of identified black tea metabolites.