Background: This systematic review and meta-analysis of randomized controlled trials (RCTs) was performed to determine the effect of quercetin administration on blood pressures and endothelial function among patients with metabolic syndrome (MetS) and related disorders.
Methods: We searched systematically online databases including Cochrane Library, EMBASE, MEDLINE, and Web of Science to identify the relevant RCTs until December 2018. Q-test and I2 statistics were applied to assess heterogeneity among included studies. Data were pooled using a random-effects model and weighted mean difference (WMD) was considered as the overall effect size.
Results: Out of 284 citations, 9 RCTs were included in the meta-analysis. We found a significant reduction in systolic plod pressure (SBP) (WMD: -1.54; 95% CI: -2.94, -0.13) and vascular cell adhesion molecule 1 (VCAM-1) (WMD: -23.52; 95% CI: -40.48, -6.56) following the intake of quercetin supplements. However, quercetin supplementation did not significantly affect diastolic blood pressure (DBP) (WMD: -2.15; 95% CI: -4.52, 0.21), E-selectin (WMD: 0.71; 95% CI: -0.97, 2.39), intercellular adhesion molecule 1 (ICAM-1) (WMD: 1.90; 95% CI: -6.67, 10.47) and endothelin-1 (WMD: -0.08; 95% CI: -0.16, 0.00).
Conclusions: In summary, the current meta-analysis demonstrated that quercetin supplementation significantly reduced SBP and VCAM-1 levels, yet did not affect DBP, endothelin-1, E-selectin and ICAM-1 among patients with MetS and related disorders.