title: Effect of green tea supplementation on blood pressure among overweight and obese adults: a protocol for a systematic review.
abstract: BACKGROUND
  Emerging randomised controlled trials (RCTs) exploring the effect of green tea (GT) supplementation or GT extract (GTE) on blood pressure (BP) among overweight and obese adults yielded inconclusive results. We aim to conduct a systematic review to summarise the evidence of RCTs until now, to clarify the efficacy of GT supplementation or GTE in BP in overweight and obese populations.
  
  
  METHODS
  The Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE and ClinicalTrials.gov will be searched to retrieve potential RCTs. Unpublished studies will be identified by searching the abstract books or websites of the three major conference proceedings: the International Society of Hypertension, the Nutrition & Health Conference and the World Congress of Nutrition and Health. A random-effects meta-analysis will be performed to pool the mean difference for the change in BP from baseline (ie, postintervention BP minus baseline BP) between intervention groups and placebo groups of the included studies, presenting the pooled results with 95% CIs. Subgroups analyses will be conducted according to different doses of GT or GTE, trial duration, geographic regions, overweight versus obese participants, and participants with versus without change in body weight after intervention. Sensitivity analysis will be performed by excluding studies classified as having a high risk of bias, applying a fixed-effects model, using the postintervention BP for analyses and excluding trials with non-study cointerventions.
  
  
  BACKGROUND
  This systematic review will be published in a peer-reviewed journal. It will be disseminated electronically and in print. Summarising the RCT evidence to clarify the efficacy in BP among overweight and obese adults will aid in making the dietary recommendation of GT and improving the clinical management of hypertension.
  
  
  BACKGROUND
  PROSPERO CRD42014007273.
authors.affiliation: Department of Clinical Epidemiology & Biostatistics, McMaster University, Hamilton, Ontario, Canada.
authors.forename: Guowei
authors.initials: G
authors.lastname: Li
authors.forename: Yuan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Lawrence
authors.initials: L
authors.lastname: Mbuagbaw
authors.forename: Anne
authors.initials: A
authors.lastname: Holbrook
authors.forename: Mitchell A H
authors.initials: MA
authors.lastname: Levine
authors.forename: Lehana
authors.initials: L
authors.lastname: Thabane
mesh_terms: D000975:Antioxidants / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects*; D019587:Dietary Supplements; D006801:Humans; D006973:Hypertension / Q000188:drug therapy / Q000517:prevention & control; D009765:Obesity / Q000503:physiopathology*; D050177:Overweight / Q000503:physiopathology*; D010936:Plant Extracts / Q000494:pharmacology*; D011788:Quality of Life; D000078202:Systematic Reviews as Topic; D013662:Tea / Q000009:adverse effects; D014665:Vasodilator Agents / Q000494:pharmacology
chemical_list: D000975:Antioxidants; D010936:Plant Extracts; D013662:Tea; D014665:Vasodilator Agents
keywords: blood pressure; green tea; obese; overweight; systematic review protocol
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