The Effects of Grape/Grape Products on Inflammatory and Oxidative Stress Markers: Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background. A growing body of evidence has demonstrated the multiple effects of the individual phenolic antioxidants of grapes. However, it is not clear whether grape and its derivatives exert anti-inflammatory effects. In this systematic review and meta-analysis, we sought to examine the effects of grape/grape products on inflammation and oxidative stress in adults. Methods. This study has been conducted based on the PRISMA checklist. A systematic literature search in PubMed, Scopus, ISI Web of Science, and the Cochrane Library was conducted, from inception until January 2022, to identify eligible trials. Mean differences and standard deviations were pooled using random-effects models. Results. Twenty-nine eligible trials were included. Grape and its products significantly increased the catalase activity (n = 3 studies, 64 participants; WMD = 5.49 U/mg protein, 95% CI: 4.76, 6.22; P<0.001; I2 = 0%; P-heterogeneity = 0.98), oxygen radical absorbance capacity (n = 5 studies, 206 participants; WMD = 90.06 µmol/l TE, 95% CI: 35.97, 144.15; P=0.001; I2 = 35.6%; P-heterogeneity = 0.18), and total antioxidant capacity (n = 4 studies, 224 participants; WMD = 62.48 µmol/l, 95% CI: 31.62, 93.33; P<0.001; I2 = 55.2%; P-heterogeneity = 0.08) and decreased thiobarbituric acid reactive substances levels (n = 5 studies, 153 participants; WMD = −0.17 nmol/mg, 95% CI: −0.31, −0.03; P=0.02; I2 = 34.2%; P-heterogeneity = 0.19). No significant change was observed for inflammatory markers. Conclusion. Although grape/grape products elicited increases in antioxidant agents, they had no significant effect on inflammatory factors. This may be related to the low levels of baseline inflammatory factors, as none of the included studies enrolled patients with acute inflammation. Further well-designed studies are warranted to examine grape’s efficacy on inflammation and oxidative stress.