title: Absorption, metabolism and excretion of Choladi green tea flavan-3-ols by humans.
abstract: Ten healthy human subjects consumed 500 mL of Choladi green tea, containing 648 mumol of flavan-3-ols after which plasma and urine were collected over a 24 h period and analysed by HPLC-MS. Plasma contained a total of ten metabolites, in the form of O-methylated, sulphated and glucuronide conjugates of (epi)catechin and (epi)gallocatechin, with 29-126 nM peak plasma concentrations (C(max)) occurring 1.6-2.3 h after ingestion, indicative of absorption in the small intestine. Plasma also contained unmetabolised (-)-epigallocatechin-3-gallate and (-)-epicatechin-3-gallate with respective C(max) values of 55 and 25 nM. Urine excreted 0-24 h after consumption of green tea contained 15 metabolites of (epi)catechin and (epi)gallocatechin, but (-)-epigallocatechin-3-gallate and (-)-epicatechin-3-gallate were not detected. Overall flavan-3-ol metabolite excretion was equivalent to 8.1% of intake, however, urinary (epi)gallocatechin metabolites corresponded to 11.4% of (epi)gallocatechin ingestion while (epi)catechin metabolites were detected in amounts equivalent to 28.5% of (epi)catechin intake. These findings imply that (epi)catechins are highly bioavailable, being absorbed and excreted to a much greater extent than most other flavonoids. It is also evident that flavan-3-ol metabolites are rapidly turned over in the circulatory system and as a consequence C(max) values are not an accurate quantitative indicator of the extent to which absorption occurs.
authors.affiliation: Plant Products and Human Nutrition Group, Division of Environmental and Evolutionary Biology, Faculty of Biomedical and Life Sciences, University of Glasgow, Glasgow, UK.
authors.forename: Angélique
authors.initials: A
authors.lastname: Stalmach
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Troufflard
authors.forename: Mauro
authors.initials: M
authors.lastname: Serafini
authors.forename: Alan
authors.initials: A
authors.lastname: Crozier
mesh_terms: D002392:Catechin / Q000031:analogs & derivatives / Q000097:blood / Q000652:urine; D002851:Chromatography, High Pressure Liquid; D005419:Flavonoids / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D006801:Humans; D007408:Intestinal Absorption; D021241:Spectrometry, Mass, Electrospray Ionization; D013662:Tea / Q000737:chemistry*
chemical_list: D005419:Flavonoids; D013662:Tea; C404987:flavan-3-ol; D002392:Catechin; C062669:epicatechin gallate; C045651:epigallocatechin gallate; C057580:gallocatechol