Effect of synbiotics and probiotics supplementation on autoimmune diseases: A systematic review and meta-analysis of clinical trials*

Background & aims: Today synbiotics are considered as immunomodulatory agents. The current systematic review and meta-analysis investigated the effect of synbiotics and probiotics on inflammatory and oxidative stress markers in autoimmune disease. Materials & methods: The English literature search was performed using PubMed, Scopus, Web of Science, and the Central Cochrane Library through March 2020. Random effects models and generic inverse variance methods were used to synthesize quantitative data by STATA14. Results: From a total of 623 entries identified via searches, ten RCTs (n = 440; 216 as intervention, 224 as controls) were included. An additional eleven studies with same intervention and different markers were also explained systematically. The pooled effect size showed that Interleukin (IL)-6 (WMD = -7.79 pg/ ml; 95% CI = -13.81, -1.77, P = 0.011), Tumor Necrosis Factor (TNF)-a (WMD = -1.05 pg/ml; 95% CI = -2.01, -0.10, P = 0.030), high sensitivity C-Reactive Protein (hs-CRP) (SMD = -0.58; 95% CI = -0.79, -0.37, P < 0.001), Malondialdehyde (MDA) (SMD = -0.36; 95% CI = -0.68, -0.04; P = 0.026), Homeostasis Model of Assessment-estimated Insulin Resistance (HOMA-IR) (WMD = -0.71; 95% CI = -1.05, -0.37, P < 0.001), and beta cell function (HOMA-b) (WMD = -15.18; 95% CI = -22.08, -8.28, P < 0.001) changed following probiotics (or synbiotics) supplementation. Also supplementation with doses more than 2 billion CFU could reduce IL-10 concentrations (WMD = -1.84; 95% CI = -2.23, 1.87; P < 0.001). Glutathione (GSH) and Total Antioxidant Capacity (TAC) levels did not influence by synbiotics and probiotics; insignificancy was remained after subgrouping for participants' age, study duration, and disease duration. Conclusion: Our findings revealed that synbiotics and probiotics supplementation has significant effect on some inflammatory and oxidative stress markers; although, the number of trials was too small to powerful conclusion and further investigations may be needed. (c) 2021 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.

Automated summary

The study found that supplementation with synbiotics and probiotics has a significant effect on certain inflammatory and oxidative stress markers, but further research is needed to confirm these findings.