The efficacy of probiotic supplementation in rheumatoid arthritis: a meta-analysis of randomized, controlled trials

Probiotics are considered as -immunomodulatory agents; their efficacy as an adjunct therapy option for rheumatoid arthritis (RA), however, remains controversial. The main aim of the present meta-analysis, therefore, was to compare available data from the published randomized, controlled trials (RCTs) recruiting adults with RA which compared probiotics with placebo. The English literature search was performed using Ovid version of Medline, EmBase, Web of Science, and the Central Cochrane library through October 2016 and supplemented by hand searching reference lists. Among 240 citations identified, 4 RCTs (153 participants; 89% female) were included. All data were pooled using a standardized mean difference (SMD) with a 95% CI. Compared to the placebo, probiotics did not change the inflammatory parameters (erythrocyte sedimentation rate, tumor necrosis factor [TNF]-alpha, interleukin [IL]-1 beta, IL-6, IL-10, and IL-12) and oxidative stress indices (total antioxidant capacity and malondialdehyde) significantly. The borderline significant reduction as a result of probiotic administration was only determined in C-reactive protein [SDM - 0.32 (95% CI - 0.65 to 0.00)]. Among disease activity indices (disease activity score [DAS], tender joint count, and swollen joint count), DAS showed a significant improvement following probiotic treatment with a SMD (95% CI) of - 0.58 (- 0.97 to - 0.19). The number of trials was too small to determine if a strain-, dose-, or duration-response effect was present. Probiotics seem to be less effective in RA; however, to reach a firm conclusion, we need further evidence.