Catechin metabolites after intake of green tea infusions

Biofactors. 1998;8(1-2):111-8. doi: 10.1002/biof.5520080119.


Green tea contains relatively large amounts of catechins, that have been recognized to be efficient free-radical scavengers. In spite of a largely described antioxidant effect, the metabolic fate of catechins in humans has been scarcely studied. An infusion of green tea (about 400 mg of catechins) was given to healthy volunteers; plasma and urine samples were collected for 5 h and 2 days, respectively. Epigallocatechin gallate and epicatechin gallate were detected in plasma samples, reaching the maximum concentration (2 microM) at 2 h. Urine samples collected at 6-48 h contained detectable amounts of final catechin metabolites, including 4-hydroxybenzoic acid, 3,4-dihydroxybenzoic acid, 3-methoxy-4-hydroxy-hippuric acid and 3-methoxy-4-hydroxybenzoic acid (vanillic acid). The total content of these metabolites averaged 60 mg. The levels of free plasma catechins account only partly for the increased (approximately +20%) total radical-trapping antioxidant parameter (TRAP) detected after green tea intake. Catechin conjugates (glucuronide and sulphate) and metabolites may add further contribution and explain the measured TRAP increase.

MeSH terms

  • Antioxidants / metabolism
  • Benzoates / urine
  • Catechin / analogs & derivatives*
  • Catechin / blood
  • Catechin / pharmacokinetics*
  • Catechin / urine
  • Humans
  • Tea*


  • Antioxidants
  • Benzoates
  • Tea
  • Catechin
  • epicatechin gallate
  • epigallocatechin gallate