The efficacy and safety of probiotics in patients with irritable bowel syndrome: Evidence based on 35 randomized controlled trials.

Background & Objectives: Irritable bowel syndrome (IBS) is a functional bowel disorder that may involve disturbance of the gastrointestinal microbiota. We performed a systematic review and meta-analysis of the efficacy and safety of probiotics in patients with IBS.

Methods: We searched the Cochrane Library, PubMed, EMBASE and Web of Science databases up to 1 April, 2019. Randomized controlled trials (RCTs) involving adults with IBS that compared probiotics to placebo or no therapy were eligible for the analysis. Dichotomous symptom data were pooled to calculate the relative risk (RR) with a 95% confidence interval (CI) of remaining symptoms after therapy. Continuous data were pooled using a standardized mean difference (SMD) with the 95% CI. Two reviewers assessed trial quality and extracted data independently.

Results: Thirty-five RCTs involving 3,452 patients were included in the analysis. Compared with placebo, patients using probiotics had a lower incidence of persistence of symptoms (RR 0.79, 95% CI 0.70 to 0.89, P < 0.0001). Also, probiotics exerted a beneficial effect on global symptoms and the abdominal pain score (SMD -0.25, 95% CI -0.36 to -0.14, P < 0.00001), bloating score (SMD -0.15, 95% CI -0.27 to -0.03, P = 0.01), and flatulence score (SMD -0.20, 95% CI -0.35 to -0.05, P = 0.01). However, patients treated with probiotics had a higher incidence of any adverse event (RR 1.21; 95% CI 1.02 to 1.44).

Conclusions: Supplementation with multi-strain probiotics can improve IBS symptoms. Further research is required if probiotics are to be adopted as a treatment for IBS.