Effect of a Multi-Strain Probiotic Supplement on Gut Microbiota Composition and Symptom Severity in Irritable Bowel Syndrome with Constipation: A Randomized Controlled Trial

Abstract

Background: Irritable bowel syndrome with constipation (IBS-C) is a common disorder of gut-brain interaction linked to
compositional gut microbiota shifts. Objective: To synthesise randomised-trial and mechanistic evidence on multi-strain
probiotics for microbiota composition and symptoms in IBS-C. Methods: Narrative review of published randomised trials,
systematic reviews and meta-analyses, and mechanistic studies identified via PubMed, Europe PMC and Crossref. Findings:
Multi-strain formulations consistently outperform placebo (pooled RR of non-improvement 0.79) and partially restore
Bifidobacterium abundance and short-chain fatty acid output. Conclusions: Multi-strain probiotics are a reasonable,
strain-dependent adjunct for IBS-C pending better-standardised trials.