Impact of quercetin on systemic levels of inflammation: a meta-analysis of randomised controlled human trials

Knowledge regarding the anti-inflammatory capability of quercetin remains inconclusive and controversial due to the heterogeneous methods and inconsistent results of RCTs. We performed a series of meta-analyses of RCTs to evaluate the impact of quercetin supplementation on inflammatory biomarkers. Three cytokines (CRP, IL-6, TNF-α) with enough eligible studies (n = 6, 5 and 4, respectively) were selected for further meta-analyses. Data from these RCTs were pooled, and both overall effect and stratified subgroup analyses were performed. No relevant overall effects on peripheral CRP, IL-6 and TNF-α were observed. Subgroup analyses revealed a significant reduction in circulating CRP in participants with diagnosed diseases (SMD: –0.24, 95% CI: –0.49, 0.00) and IL-6 in females (SMD: –1.37, 95% CI: –1.93, –0.81), subjects with diagnosed diseases (SMD: –1.37, 95% CI: –1.93, –0.81) and with high-dose interventions (SMD: –0.69, 95% CI: –1.10, –0.38). In conclusion, consumption of quercetin is a promising therapeutic strategy for chronic disease management.