Effect of milk tripeptides on blood pressure: a meta-analysis of randomized controlled trials.

OBJECTIVE To better understand and summarize the relation between milk peptide intake and blood pressure (BP), we conducted a meta-analysis of randomized controlled trials to assess the effects of the milk-derived tripeptides isoleucine-proline-proline and valine-proline-proline on BP in prehypertensive and hypertensive subjects. METHODS Nine studies including 12 trials published between 1996 and 2005 with a total of 623 participants were included. Two researchers independently extracted data from the original publications. A fixed-effects model was used for meta-analysis because of the homogeneity among trials. RESULTS Significant decreases of 4.8 mmHg (95% confidence interval 3.7-6.0) in systolic BP and 2.2 mmHg (95% confidence interval 1.3-3.1) in diastolic BP were found after the pooling of these trials. When trials were separated by BP status, hypotensive effects appeared to be larger in hypertensive subjects than in prehypertensive subjects. As a trend, the hypotensive effects became more obvious as the intervention lengthened. CONCLUSION Our analysis provided evidence that milk-derived tripeptides have hypotensive effects in prehypertensive and hypertensive subjects.