The role of probiotic supplementation in inflammatory biomarkers in adults: an umbrella meta-analysis of randomized controlled trials

Objective Despite the increasing evidence for probiotics' anti-inflammatory effects, the results of meta-analyses remain inconsistent. The present umbrella meta-analysis aimed to investigate the effects of probiotic supplementation on inflammatory biomarkers. Methods We performed a wide-ranging systematic search in several databases, including PubMed, Web of Science, Scopus, EMBASE, and Google Scholar up to April 2023. The overall effect sizes were calculated using effect size (ES) values and their corresponding confidence intervals ( CI). Results Out of a total of 580 related articles, 39 studies were qualified for inclusion in the analysis. The results of the analysis revealed a significant reduction of C-reactive protein (CRP) (ES = -1.02; 95% CI: -1.23, -0.80, p < 0.001; I-2: 94.1%, p < 0.001), TNF-alpha (ES = -0.35; 95% CI: -0.50, -0.20, p < 0.001; I-2: 75.6%, p < 0.001), and interleukin-6 (IL-6) levels (ES = -0.36; 95% CI: -0.59, -0.13, p = 0.002; I-2: 85.6%, p < 0.001), following probiotic supplementation. Conclusion Probiotic supplementation significantly reduced serum concentrations of TNF-alpha, CRP, and IL-6. Thus, probiotic supplementation can be considered adjuvant therapy to alleviate inflammation in various inflammatory conditions.