Metabolic fate of tea polyphenols in humans

Polyphenols, a ubiquitous group of secondary plant metabolites sharing at least one aromatic ring structure with one or more hydroxyl groups, represent a large group of natural antioxidants abundant in fruits, vegetables, and beverages, such as grape juice, wine, and tea, and are widely considered to contribute to health benefits in humans. However, little is yet known concerning their bioactive forms in vivo and the mechanisms by which they may alter our metabolome, which ultimately contribute toward disease prevention. Here we report a study to determine the metabolic fate of polyphenolic components in a Chinese tea (Pu-erh) in human subjects using a metabonomic profiling approach coupled with multivariate and univariate statistical analysis. Urine samples were collected at 0 h, 1 h, 3 h, 6 h, 9 h, 12 h, and 24 h within the first 24 h and once a day during a 6 week period including a 2 week baseline phase, a 2 week daily Pu-erh tea ingestion phase, and a 2 week "wash-out" phase, and they were analyzed by gas chromatography mass spectrometry and liquid chromatography mass spectrometry. The dynamic concentration profile of bioavailable plant molecules (due to in vivo absorption and the hepatic and gut bacterial metabolism) and the human metabolic response profile were measured and correlated with each other. This study demonstrates that the metabonomic strategy will enable us to integrate the overwhelming amount of metabolic end points as a systems' response to the absorption, metabolism, and disposition of a multicomponent botanical intervention system, leading to a direct elucidation of their mechanisms of action.