Abstract
BACKGROUND: In clinical trials, peptides derived from food proteins have shown an effect on blood pressure. This biological mechanism is mainly due to inhibition of angiotensin-I-converting enzyme (ACE), thereby regulating blood pressure through the renin-angiotensin system. A meta-analysis of these trials is needed to better quantify their effect, sources of variation, and possible publication bias. OBJECTIVE: To perform a meta-analysis of placebo-controlled clinical trials on peptides derived from food proteins and their effect on blood pressure. DESIGN: Trials identified using a defined search strategy in PubMed were included in the meta-analysis, and their pooled effect was estimated with a random effects model. RESULTS: Pooled effect of peptides was -5.13 mmHg (95% CI: -7.12, -3.14) for systolic blood pressure, and -2.42 mmHg (95% CI: -3.82, -1.03) for diastolic blood pressure. There were indications of publication bias for diastolic blood pressure data. CONCLUSIONS: Peptides derived from food proteins may lead to significantly reduced blood pressure and could therefore be a supplement or alternative to pharmaceutical treatment for mild hypertension. Their effect seems more pronounced, or at least comparable, to that of other food components studied by randomized controlled trials. A high proportion of the reported trials was carried out using the well-known ACE inhibiting tripeptides - Valine-Proline-Proline (VPP) and Isoleucine-Proline-Proline (IPP).