Efficacy and Safety of Postbiotics in Irritable Bowel Syndrome: A Systematic Review and Meta-Analysis

Postbiotics, preparations of inanimate microorganisms and/or their components with health benefits, may offer potential advantages in the management of IBS, but evidence remains limited. We conducted the first systematic review and meta-analysis to assess the efficacy and safety of postbiotics in adults with IBS.

PubMed, Scopus, Embase, and Web of Science were searched from inception to August 2025 for randomized controlled trials (RCTs) comparing postbiotics with placebo in adults diagnosed with IBS by Rome III or IV criteria. Primary outcomes were changes in the IBS Symptom Severity Scale (IBS-SSS) and achievement of ≥ 30% abdominal pain reduction. Secondary outcomes included quality of life (QoL) and treatment-emergent adverse events (TEAEs). Risk of bias was assessed using Cochrane RoB 2.0 and certainty of evidence using GRADE. Meta-analyses were conducted using RevMan 5.4.

Four RCTs including 1062 participants were analyzed. Postbiotics significantly reduced IBS-SSS scores compared with placebo (standardized mean difference [SMD] - 1.36, 95% CI -1.75 to -0.97; p < 0.00001). Postbiotics increased the likelihood of achieving a clinically meaningful pain response (risk ratio [RR] 2.46, 95% CI 1.96-3.57; p < 0.00001). QoL improved with oral capsule formulations (SMD 0.84, 95% CI 0.67-1.01; I² = 0%), but not when an enema-based study was included. TEAE rates were similar between groups (RR 0.68, 95% CI 0.34-1.35; p = 0.27). Heterogeneity was moderate to substantial. Certainty of evidence was low.

Postbiotics may improve IBS symptom severity and abdominal pain, with oral formulations showing potential QoL benefits and comparable safety to placebo. Larger, standardized RCTs are required to confirm these findings.