Postbiotic Supplementation and Intestinal Barrier Function Markers in Adults with Irritable Bowel Syndrome: A Randomized, Placebo-Controlled Trial

Abstract

Background: Loss of intestinal barrier integrity, reflected by elevated zonulin, intestinal fatty acid-binding protein (I-FABP) and
circulating lipopolysaccharide, is increasingly implicated in irritable bowel syndrome (IBS) symptom generation. Objective: To
synthesise evidence on postbiotic (heat-inactivated bacteria, cell-free supernatants, purified metabolites) supplementation and
barrier-function markers in adults with IBS. Methods: Narrative review of published randomised trials, systematic reviews and
meta-analyses, and mechanistic studies. Findings: Postbiotic and heat-inactivated probiotic preparations consistently improve
IBS symptom severity and, where measured, lower circulating zonulin and LPS-binding protein and upregulate tight-junction
protein expression, broadly paralleling live-strain probiotic effects. Conclusions: Postbiotics represent a mechanistically
plausible, safety-favourable barrier-targeted adjunct for IBS management, though direct barrier-marker trial data remain limited.