title: Bioavailability and antioxidant activity of tea flavanols after consumption of green tea, black tea, or a green tea extract supplement.
abstract: BACKGROUND
  Green and black tea polyphenols have been extensively studied as cancer chemopreventive agents. Many in vitro experiments have supported their strong antioxidant activity. Additional in vivo studies are needed to examine the pharmacokinetic relation of absorption and antioxidant activity of tea polyphenols administered in the form of green or black tea or tea extract supplements.
  
  
  OBJECTIVE
  The purpose of this study was to compare the pharmacokinetic disposition of tea polyphenols and their effect on the antioxidant capacity in plasma 8 h after a bolus consumption of either green tea, black tea, or a green tea extract supplement.
  
  
  METHODS
  Thirty healthy subjects were randomly assigned to 3 different sequences of green tea, black tea, or a green tea extract supplement in a 3 x 3 crossover design with a 1-wk washout period in between treatments.
  
  
  RESULTS
  Flavanol absorption was enhanced when tea polyphenols were administered as a green tea supplement in capsule form and led to a small but significant increase in plasma antioxidant activity compared with when tea polyphenols were consumed as black tea or green tea. All 3 interventions provided similar amounts of (-)-epigallocatechin-3-gallate.
  
  
  CONCLUSIONS
  Our observations suggest that green tea extract supplements retain the beneficial effects of green and black tea and may be used in future chemoprevention studies to provide a large dose of tea polyphenols without the side effects of caffeine associated with green and black tea beverages.
authors.affiliation: Center for Human Nutrition, David Geffen School of Medicine and the Department of Biostatistics, School of Public Health, University of California, Los Angeles, 90095, USA. shenning@mednet.ucla.edu
authors.forename: Susanne M
authors.initials: SM
authors.lastname: Henning
authors.forename: Yantao
authors.initials: Y
authors.lastname: Niu
authors.forename: Nicolas H
authors.initials: NH
authors.lastname: Lee
authors.forename: Gail D
authors.initials: GD
authors.lastname: Thames
authors.forename: Rosario R
authors.initials: RR
authors.lastname: Minutti
authors.forename: Hejing
authors.initials: H
authors.lastname: Wang
authors.forename: Vay Liang W
authors.initials: VL
authors.lastname: Go
authors.forename: David
authors.initials: D
authors.lastname: Heber
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000975:Antioxidants / Q000493:pharmacokinetics*; D001628:Beverages; D001682:Biological Availability; D002110:Caffeine / Q000008:administration & dosage / Q000009:adverse effects; D002392:Catechin / Q000031:analogs & derivatives*; D018592:Cross-Over Studies; D019587:Dietary Supplements; D005260:Female; D005419:Flavonoids / Q000494:pharmacology*; D044948:Flavonols / Q000097:blood / Q000493:pharmacokinetics* / Q000652:urine; D006801:Humans; D007408:Intestinal Absorption; D008297:Male; D010636:Phenols / Q000494:pharmacology*; D059808:Polyphenols; D013662:Tea / Q000737:chemistry*
chemical_list: D000975:Antioxidants; D005419:Flavonoids; D044948:Flavonols; D010636:Phenols; D059808:Polyphenols; D013662:Tea; D002110:Caffeine; D002392:Catechin; C045651:epigallocatechin gallate