Purpose: The evidence has suggested that resveratrol has anti-inflammatory effect; however, the results are inconsistent and inconclusive. The aim of this study was to assess the effect of resveratrol supplementation on the levels of inflammatory markers through a systematic review and meta-analysis of available randomized controlled trials (RCTs).
Methods: A search strategy was completed using Medline, ISI Web of Science, Directory of Open Access Journal, SID, ProQuest, Cochrane Library, Scopus, and EMBASE up to May 2017, to identify placebo-controlled RCTs that assessed resveratrol effects on circulating (serum and plasma) inflammatory markers (interleukin [IL]-6, tumor necrosis factor-α [TNF-α], and high-sensitivity C-reactive protein [hs-CRP]) among adult participants aged 17 years and older in 17 RCTs with a total of 736 subjects. The evaluation of study quality was performed using the Jadad scale. Weighted mean difference (WMD) was calculated for evaluating the changes in the inflammatory markers using fixed-effects or random-effects models. We performed subgroup and sensitivity analyses to evaluate the heterogeneity of the studies.
Findings: Seventeen RCTs, including 736 subjects, fulfilled the eligibility criteria and were selected for analyses. The results of meta-analysis found significant reductions in the level of TNF-α (WMD, -0.44; 95% CI, -0.71 to -0.164; P = 0.002; Q statistic = 21.60; I2 = 49.1%; P = 0.02) and hs-CRP (WMD, -0.27; 95% CI, -0.5 to -0.02; P = 0.033; Q statistic = 26.95; I2 = 51.8%; P = 0.013) after supplementation with resveratrol. Resveratrol supplementation had no significant effect on the level of IL-6 (WMD, -0.16; 95% CI, -0.53 to 0.20; P = 0.38; Q statistic = 36.0; I2 = 72.3%; P = 0.001). Statistically significant heterogeneity was observed for the type of sample in IL-6 and study duration in inflammatory markers IL-6, TNF-α, and hs-CRP.
Implications: Available evidence from RCTs suggests that resveratrol supplementation significantly reduced TNF-α and hs-CRP levels. Significant improvement in inflammatory markers support resveratrol as an adjunct to pharmacologic management of metabolic diseases.
Keywords: TNF-α; hs-CRP; inflammation; meta-analysis; resveratrol; systematic review.
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