title: The effects of chronic tea intake on platelet activation and inflammation: a double-blind placebo controlled trial.
abstract: BACKGROUND
  Tea drinking appears to protect against the development of coronary heart disease (CHD), but the mediating pathways are uncertain. We studied the effects of 6 weeks of black tea or placebo on platelet activation, C-reactive protein (CRP), total antioxidant status, and soluble (s) P-Selectin in a randomized double-blind trial.
  
  
  METHODS
  Healthy non-smoking men aged 18-55 years were randomized to black tea (N=37) or placebo (N=38) following a 4-week washout period during which they drank no tea, coffee or caffeinated beverages, but consumed caffeinated placebo tea. Bloods were drawn after 6 weeks of treatment. Platelet activation was assessed by measuring leukocyte-platelet aggregates using whole blood flow cytometry.
  
  
  RESULTS
  Following treatment, the tea group had fewer monocyte-platelet aggregates (means 5.84 versus 6.60%, P=0.027), neutrophil-platelet aggregates (P=0.017), total leukocyte-platelet aggregates (P=0.027), and lower plasma C-reactive protein (means 0.76 versus 0.97 mg/L, P=0.05) than the placebo group. There were no differences in total antioxidant status or soluble P-Selectin.
  
  
  CONCLUSIONS
  Chronic tea consumption reduces platelet activation and plasma C-reactive protein in healthy men. Effects cannot be attributed to observer bias or lifestyle confounders. These effects of tea may contribute to sustained cardiovascular health.
authors.affiliation: Department of Epidemiology and Public Health, University College London, 1-19 Torrington Place, London WC1E 6BT, UK. a.steptoe@ucl.ac.uk
authors.forename: Andrew
authors.initials: A
authors.lastname: Steptoe
authors.forename: E Leigh
authors.initials: EL
authors.lastname: Gibson
authors.forename: Raisa
authors.initials: R
authors.lastname: Vuononvirta
authors.forename: Mark
authors.initials: M
authors.lastname: Hamer
authors.forename: Jane
authors.initials: J
authors.lastname: Wardle
authors.forename: Jane A
authors.initials: JA
authors.lastname: Rycroft
authors.forename: John F
authors.initials: JF
authors.lastname: Martin
authors.forename: Jorge D
authors.initials: JD
authors.lastname: Erusalimsky
mesh_terms: D000293:Adolescent; D000328:Adult; D000975:Antioxidants / Q000032:analysis; D001628:Beverages; D002097:C-Reactive Protein / Q000032:analysis; D004311:Double-Blind Method; D006801:Humans; D007249:Inflammation; D008297:Male; D008875:Middle Aged; D018384:Oxidative Stress / Q000187:drug effects*; D019007:P-Selectin / Q000097:blood; D015539:Platelet Activation / Q000187:drug effects*; D013662:Tea
chemical_list: D000975:Antioxidants; D019007:P-Selectin; D013662:Tea; D002097:C-Reactive Protein