Low-FODMAP Diet Versus Standard Dietary Advice in Irritable Bowel Syndrome: A Randomized Controlled Trial

Abstract

Background: A diet low in fermentable oligo-, di-, monosaccharides and polyols (FODMAPs) is widely recommended for irritable
bowel syndrome (IBS), but its benefit relative to standard first-line dietary advice remains debated. Objective: To synthesise trial and review evidence comparing low-FODMAP diet with standard dietary advice for symptom control, reintroduction/adherence, microbiota effects, and IBS subtypes. Methods: Narrative review of published randomised trials, systematic reviews/meta-analyses, and mechanistic studies. Findings: Head-to-head trials and pooled meta-analyses show low-FODMAP diet and standard dietary advice produce broadly equivalent global symptom response (50% vs 46% responders in one trial; 52% vs 41% in another), though low-FODMAP more consistently improves abdominal pain. Reintroduction restores tolerated FODMAPs and supports adherence, while restriction transiently reduces luminal Bifidobacteria. Conclusions: Both approaches are effective first-line options; standard advice first, with low-FODMAP reserved for non-responders and followed by structured reintroduction, is the most evidence-consistent strategy.