The Effects of Resveratrol Supplementation on Endothelial Function and Blood Pressures Among Patients with Metabolic Syndrome and Related Disorders: A Systematic Review and Meta-Analysis of Randomized Controlled Trials Abstract Introduction There are current trials investigating the effect of resveratrol supplementation on endothelial function and blood pressures among patients with metabolic syndrome (MetS); however, the findings are controversial. Aim This systematic review and meta-analysis of randomized controlled trials (RCTs) were carried out to summarize the effects of resveratrol supplementation on endothelial activation and blood pressures among patients with MetS and related disorders. Methods We searched systematically online databases including: PubMed-Medline, Embase, ISI Web of Science and Cochrane Central Register of Controlled Trials until October, 2018. Two independent authors extracted data and assessed the quality of included articles. Data were pooled using the fixed- or random-effects model and considered as standardized mean difference (SMD) with 95% confidence intervals (95% CI). Results Out of 831 electronic citations, 28 RCTs (with 33 findings reported) were included in the meta-analyses. The findings showed that resveratrol intervention significantly increased flow-mediated dilatation (FMD) levels (SMD 1.77; 95% CI 0.25, 3.29; P = 0.02; I2: 96.5). However, resveratrol supplements did not affect systolic blood pressure (SBP) (SMD − 0.27; 95% CI − 0.57, 0.03; P = 0.07; I2: 88.9) and diastolic blood pressure (DBP) (SMD − 0.21; 95% CI − 0.52, 0.11; P = 0.19; I2: 89.8). Conclusions Resveratrol supplementation significantly increased FMD among patients with MetS and related disorders, but did not affect SBP and DBP. Additional prospective studies are needed to investigate the effect of resveratrol supplementation on endothelial function and blood pressures, using higher-dose of resveratrol with longer durations.