The effects of whey protein on blood pressure: A systematic review and dose-response meta-analysis of randomized controlled trials

AimsThis systematic review and dose-response meta-analysis was conducted to summarize data from available clinical trials on the effects of whey protein (WP) supplementation on blood pressure (BP) in adults.Data synthesisA comprehensive literature search was conducted in the electronic databases PubMed, Web of Science, ProQuest, Embase, and SCOPUS from inception to October 2022. Weighted mean differences (WMD) and 95% confidence intervals (CI) were calculated to assess pooled effect sizes. Heterogeneity between studies was assessed using the Cochran's Q test and I². Subgroup analysis was performed to assess potential sources of heterogeneity. The dose–response relationship was assessed using fractional polynomial modeling. Of the 2,840 records, 18 studies with 1,177 subjects were included. Pooled analysis showed that whey protein supplementation resulted in a significant reduction in systolic blood pressure (WMD: −1.54 mmHg; 95% CI: −2.85 to −0.23, p = 0.021), with significant heterogeneity between studies (I² = 64.2%, p < 0.001), but not for diastolic blood pressure (DBP) (WMD: −0.27 mmHg; 95% CI: −1.14, 0.59, p = 0.534) with high heterogeneity between studies (I² = 64.8%, p < 0.001). However, WP supplementation significantly reduced DBP at a dose of ˃30 g/day, in RCTs that used WP isolate powder for their intervention, in sample sizes ≤100, in studies with an intervention duration of ≤10 weeks, and in those studies that were conducted in patients with hypertension and had participants with a BMI of 25–30 kg/m².ConclusionThis meta-analysis demonstrated that WP intake significantly reduced SBP levels. Further large-scale studies are needed to specify the exact mechanism, and optimal dosage of WP supplementation to obtain a beneficial effect on BP.