Absorption, metabolism and excretion of Choladi green tea flavan-3-ols by humans

Mol Nutr Food Res. 2009 May;53 Suppl 1:S44-53. doi: 10.1002/mnfr.200800169.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Catechin / analogs & derivatives
  • Catechin / blood
  • Catechin / urine
  • Chromatography, High Pressure Liquid
  • Flavonoids / administration & dosage
  • Flavonoids / blood
  • Flavonoids / pharmacokinetics*
  • Humans
  • Intestinal Absorption
  • Spectrometry, Mass, Electrospray Ionization
  • Tea / chemistry*

Substances

  • Flavonoids
  • Tea
  • flavan-3-ol
  • Catechin
  • epicatechin gallate
  • epigallocatechin gallate
  • gallocatechol