title: Effect of tea on blood pressure for secondary prevention of cardiovascular disease: a systematic review and meta-analysis of randomized controlled trials.
abstract: BACKGROUND
  Tea has been proposed as an antihypertensive agent for individuals with elevated blood pressure, yet the evidence for this has not been systematically reviewed to date.
  
  
  OBJECTIVE
  The aim of this review was to evaluate the effects of tea on blood pressure in individuals within the prehypertensive and hypertensive blood pressure ranges.
  
  
  METHODS
  The CENTRAL, PubMed, Embase, and Web of Science databases were searched for all relevant studies published from 1946 to September 27, 2013.
  
  
  METHODS
  The selection criteria included randomized controlled trials of adults whose blood pressure was within hypertensive or prehypertensive ranges and in which the applied intervention was green or black tea; controls consisting of placebo, minimal tea intervention, or no intervention; and a follow-up period of at least 2 months.
  
  
  METHODS
  Two reviewers independently extracted data on participants, interventions, comparators, outcomes, and study design. Mean differences (MDs) and 95% confidence intervals (95%CIs) were pooled to generate summary effect estimates.
  
  
  RESULTS
  Meta-analyses of 10 trials (834 participants) showed statistically significant reductions in systolic blood pressure (MD -2.36 mmHg, 95%CI -4.20 to -0.52) and diastolic blood pressure (MD -1.77 mmHg, 95%CI -3.03 to -0.52) with tea consumption.
  
  
  CONCLUSIONS
  Consumption of green or black tea can reduce blood pressure in individuals within prehypertensive and hypertensive ranges, although further investigation with studies of longer duration and stronger methodological quality is warranted to confirm these findings.
authors.affiliation: J. Yarmolinsky, was with the London School of Hygiene and Tropical Medicine, London, United Kingdom, and is currently with the Postgraduate Studies Program in Epidemiology, School of Medicine, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil. G. Gon and P. Edwards are with the London School of Hygiene and Tropical Medicine, London, United Kingdom. At the time of manuscript preparation, J. Yarmolinsky was with the London School of Hygiene and Tropical Medicine, London, UK. jamesyarmolinsky@gmail.com.
authors.forename: James
authors.initials: J
authors.lastname: Yarmolinsky
authors.affiliation: J. Yarmolinsky, was with the London School of Hygiene and Tropical Medicine, London, United Kingdom, and is currently with the Postgraduate Studies Program in Epidemiology, School of Medicine, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil. G. Gon and P. Edwards are with the London School of Hygiene and Tropical Medicine, London, United Kingdom. At the time of manuscript preparation, J. Yarmolinsky was with the London School of Hygiene and Tropical Medicine, London, UK.
authors.forename: Giorgia
authors.initials: G
authors.lastname: Gon
authors.affiliation: J. Yarmolinsky, was with the London School of Hygiene and Tropical Medicine, London, United Kingdom, and is currently with the Postgraduate Studies Program in Epidemiology, School of Medicine, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil. G. Gon and P. Edwards are with the London School of Hygiene and Tropical Medicine, London, United Kingdom. At the time of manuscript preparation, J. Yarmolinsky was with the London School of Hygiene and Tropical Medicine, London, UK.
authors.forename: Phil
authors.initials: P
authors.lastname: Edwards
mesh_terms: D000959:Antihypertensive Agents / Q000494:pharmacology / Q000627:therapeutic use*; D001794:Blood Pressure / Q000187:drug effects*; D028241:Camellia sinensis; D006801:Humans; D006973:Hypertension / Q000517:prevention & control*; D008517:Phytotherapy; D010936:Plant Extracts / Q000494:pharmacology / Q000627:therapeutic use*; D016032:Randomized Controlled Trials as Topic; D055502:Secondary Prevention; D013662:Tea
chemical_list: D000959:Antihypertensive Agents; D010936:Plant Extracts; D013662:Tea
keywords: blood pressure; cardiovascular disease; hypertension; randomized control trials; tea