Profiling Inflammatory Biomarkers following Curcumin Supplementation: An Umbrella Meta-Analysis of Randomized Clinical Trials

Objective. Several meta-analyses have shown that curcumin can reduce inflammatory biomarkers, but the findings are inconsistent. The objective of the present umbrella meta-analysis was to provide a more accurate estimate of the overall effects of curcumin on inflammatory biomarkers. Methods. The following international databases were systematically searched until March 20, 2022: PubMed, Scopus, Embase, Web of Science, and Google Scholar. A random-effects model was applied to evaluate the effects of curcumin on inflammatory biomarkers. Meta-analysis studies investigating the effects of curcumin supplementation on inflammatory biomarkers with corresponding effect sizes (ES) and confidence intervals (CI) were included in the umbrella meta-analysis. GRADE (Grading of Recommendations Assessment, Development, and Evaluation) was used to evaluate the certainty of evidence. Results. A meta-analyses of ten studies with 5,870 participants indicated a significant decrease in C-reactive protein (CRP) (ES = -0.74; 95% CI: -1.11, -0.37, p < 0.001; I-2 = 62.1%, p=0.015), interleukin 6 (IL-6) (ES = -1.07; 95% CI: -1.71, -0.44, p < 0.001; I-2 = 75.6%, p < 0.001), and tumour necrosis factor alpha (TNF-alpha) levels (ES: -1.92, 95% CI: -2.64, -1.19, p < 0.0; I-2 = 18.1%, p=0.296) following curcumin supplementation. Greater effects on CRP and TNF-alpha were evident in trials with a mean age > 45 years and a sample size > 300 participants. Conclusion. The umbrella of meta-analysis suggests curcumin as a promising agent in reducing inflammation as an adjunctive therapeutic approach in diseases whose pathogenesis is related to a higher level of inflammatory biomarkers.