title: Effect of oral L-arginine supplementation on blood pressure: a meta-analysis of randomized, double-blind, placebo-controlled trials.
abstract: BACKGROUND
  Previous studies suggest that L-arginine, an amino acid and a substrate of nitric oxide synthase, may have blood pressure (BP)-lowering effect. Because some studies were performed with limited number of patients with hypertension and therefore limited statistical power with sometimes inconsistent results, we aimed to examine the effect of oral L-arginine supplementation on BP by conducting a meta-analysis of randomized, double-blind, placebo-controlled trials.
  
  
  METHODS
  PubMed, Cochrane Central Register of Controlled Trials, and the ClinicalTrials.gov databases were searched through June 2011 to identify randomized, double-blind, placebo-controlled trials of oral L-arginine supplementation on BP in humans. We also reviewed reference lists of obtained articles. Either a fixed-effects or, in the presence of heterogeneity, a random-effects model was used to calculate the combined treatment effect.
  
  
  RESULTS
  We included 11 randomized, double-blind, placebo-controlled trials involving 387 participants with oral L-arginine intervention ranging from 4 to 24 g/d. Compared with placebo, L-arginine intervention significantly lowered systolic BP by 5.39 mm Hg (95% CI -8.54 to -2.25, P = .001) and diastolic BP by 2.66 mm Hg (95% CI -3.77 to -1.54, P < .001). Sensitivity analyses restricted to trials with a duration of 4 weeks or longer and to trials in which participants did not use antihypertensive medications yielded similar results. Meta-regression analysis suggested an inverse, though insignificant (P = .13), relation between baseline systolic BP and net change in systolic BP.
  
  
  CONCLUSIONS
  This meta-analysis provides further evidence that oral L-arginine supplementation significantly lowers both systolic and diastolic BP.
authors.affiliation: Department of Nutrition and Food Hygiene, School of Public Health, Soochow University, Suzhou, China.
authors.forename: Jia-Yi
authors.initials: JY
authors.lastname: Dong
authors.forename: Li-Qiang
authors.initials: LQ
authors.lastname: Qin
authors.forename: Zengli
authors.initials: Z
authors.lastname: Zhang
authors.forename: Youyou
authors.initials: Y
authors.lastname: Zhao
authors.forename: Junkuan
authors.initials: J
authors.lastname: Wang
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Arigoni
authors.forename: Weiguo
authors.initials: W
authors.lastname: Zhang
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000368:Aged; D000959:Antihypertensive Agents / Q000008:administration & dosage*; D001120:Arginine / Q000008:administration & dosage*; D001794:Blood Pressure / Q000187:drug effects; D019587:Dietary Supplements; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D006973:Hypertension / Q000188:drug therapy*; D008297:Male; D008875:Middle Aged; D016032:Randomized Controlled Trials as Topic; D055815:Young Adult
chemical_list: D000959:Antihypertensive Agents; D001120:Arginine