Can resveratrol supplement change inflammatory mediators? A systematic review and meta-analysis on randomized clinical trials

Background Resveratrol as a polyphenolic compound might be able to reduce inflammatory mediators. Change in inflammatory state is identified by the measurement of inflammatory mediators such as interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), and C-reactive protein (CRP). The objective of this study is to conduct a systematic review and meta-analysis on randomized controlled trials that assessed the effect of resveratrol on concentration of serum inflammatory mediators. Method Systematic search was performed up to October 2017 using ISI web of science, PubMed, Scopus, EMBASE, and Google scholar. Weighted mean difference was estimated either by subtracting baseline values from post-intervention value or as the post-intervention values. Fixed effect model was applied to analyze data where heterogeneity was < 25%; otherwise, random effects models were applied. The protocol was registered with PROSPERO (No. CRD42018085098). Results The meta-analysis and systematic review considered 15 trials, involving 658 adults aged 18-75 years. Resveratrol significantly reduced serum CRP levels (WMD = -0.54; 95% CI: -0.78, -0.30; I-2 = 77.7%; P < 0.0001), but it had no significant effect on serum IL-6 (WMD = -0.06; 95% CI: -0.27, 0.14; I-2 = 62.0%; P = 0.005) and TNF-alpha levels (WMD = -0.20; 95% CI: -0.55, 0.16; I-2 = 87.2%; P < 0.0001). Resveratrol intake reduced TNF-alpha in young subjects (WMD = -0.34; 95% CI: -0.57, -0.12; I-2 = 60.5%; P = 0.038) and obese individuals (WMD = -1.52; 95% CI: -2.87, -0.16; I-2 = 74.1%; P = 0.004). Conclusion The analysis indicated possible decreasing effect of resveratrol on CRP, but it might not be able to change IL-6 and TNF-alpha concentrations. More studies, separately on males and females with obesity, and varied age, are necessary.