Green tea flavan-3-ols: Colonic degradation and urinary excretion of catabolites by humans

Suri Roowi, Angelique Stalmach, William Mullen, Michael E.J. Lean, Christine A. Edwards And, Alan Crozier

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226 Citations (Scopus)

Abstract

Following the ingestion of green tea, substantial quantities of flavan-3-ols pass from the small to the large intestine (Stalmach et al. Mol. Nutr. Food Res. 2009, 53, S44-S53; Mol. Nutr. Food Res. 2009, doi: 10.1002/mnfr.200900194). To investigate the fate of the flavan-3-ols entering the large intestine, where they are subjected to the action of the colonic microflora, (-)-epicatechin, (-)epigallocatechin, and (-)-epigallocatechin-3-0- gallate were incubated in vitro with fecal slurries and the production of phenolic acid catabolites was determined by GC-MS. In addition, urinary excretion of phenolic catabolites was investigated over a 24 h period after ingestion of either green tea or water by healthy volunteers with a functioning colon. The green tea was also fed to ileostomists, and 0-24 h urinary excretion of phenolic acid catabolites was monitored. Pathways are proposed for the degradation of green tea flavan-3-ols in the colon and further catabolism of phenolic compounds passing into the circulatory system from the large intestine, prior to urinary excretion in quantities corresponding to ca. 40% of intake compared with ca. 8% absorption of flavan-3-ol methyl, glucuronide, and sulfate metabolites in the small intestine. The data obtained point to the importance of the colonic microflora in the overall bioavailability and potential bioactivity of dietary flavonoids.

Original languageEnglish
Pages (from-to)1296-1304
Number of pages9
JournalJournal of Agricultural and Food Chemistry
Volume58
Issue number2
DOIs
Publication statusPublished - 27 Jan 2010

Keywords

  • Catabolites
  • Colonic degradation
  • Flavan-3-ols
  • Green tea
  • Urinary excretion

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