The effect of whole grape products on blood pressure and vascular function: A systematic review and meta-analysis of randomized controlled trials

Background and aims: Grape consumption-associated improvements in cardiovascular health have received significant attention over the last few years; however, major gaps have remained in the meta-evidence related to this topic. This systematic review and meta-analysis of randomized controlled trials (RCTs) was performed to explore the effect of whole grapes and its products on blood pressure, endothelial function, heart rate, and pulse rate.Methods and results: Four database (PubMed, Scopus, Web of Sciences, and the Cochrane Library) were searched until the 14th of January 2022. The pooled effect size of interested outcomes was calculated using the random-effects model. Thirty eligible RCTs were identified. Pooled results indicated that compared to the control group, consumption of grape products significantly decreased systolic blood pressure (SBP) (WMD =-3.17 mmHg; 95% CI:-5.36,-0.99 mmHg; P = 0.004; I-2 = 64%; P-heterogeneity<0.001); while, vascular cell adhesion molecule-1 (VCAM-1) increased (WMD = 34.11 ng/ml; 95% CI: 0.98, 67.25 ng/ml; P = 0.04; I-2 = 2%; P-heterogeneity = 0.4). Although, the certainty of evidence was low and very low, respectively. No significant effect was observed on diastolic blood pressure, endothelial function, heart rate, pulse rate, and soluble intercellular adhesion molecule-1 (sICAM-1). In a subgroup analysis, consumption of whole grape products (raisin and grape powder) induced a significant decrease in SBP (WMD =-2.69 mmHg; 95% CI:-4.81,-0.57; P = 0.01; I-2 = 18.1%; P-heterogeneity < 0.001), while grape juice did not.Conclusion: The low certainty of evidence from RCTs revealed that consumption of grape products, especially in whole forms, resulted in a small reduction of SBP but did not influence other markers of cardiovascular health.