Effect of probiotic fermented milk on blood pressure: a meta-analysis of randomised controlled trials

Previous studies have suggested that probiotic fermented milk may possess blood pressure (BP)-lowering properties. In the present study, we aimed to systematically examine the effect of probiotic fermented milk on BP by conducting a meta-analysis of randomised controlled trials. PubMed, Cochrane library and the ClinicalTrials.gov databases were searched up to March 2012 to identify eligible studies. The reference lists of the obtained articles were also reviewed. Either a fixed-effects or a random-effects model was used to calculate the combined treatment effect. Meta-analysis of fourteen randomised placebo-controlled trials involving 702 participants showed that probiotic fermented milk, compared with placebo, produced a significant reduction of 3.10mmHg (95% CI -4.64, -1.56) in systolic BP and 1.09mmHg (95% CI -2.11, -0.06) in diastolic BP. Subgroup analyses suggested a slightly greater effect on systolic BP in hypertensive participants than in normotensive ones (-3.98 v. -2.09 mmHg). Analysis of trials conducted in Japan showed a greater reduction than those conducted in European countries for both systolic BP (-6.12 v. -2.08 mmHg) and diastolic BP (-3.45 v. -0.52 mmHg). Some evidence of publication bias was present, but sensitivity analysis excluding small trials that reported extreme results only affected the pooled effect size minimally. In summary, the present meta-analysis suggested that probiotic fermented milk has BP-lowering effects in pre-hypertensive and hypertensive subjects.