A Randomized Controlled Trial Comparing Low-FODMAP and Gluten-Free Diets on Gastrointestinal Symptoms, Nutritional Status, and Quality of Life in Irritable Bowel Syndrome

Abstract

Background/Aims: Irritable bowel syndrome (IBS) is a common chronic gastrointestinal disorder that requires a symptom-based treatment approach, in which dietary and lifestyle modifications play a central role in reducing symptoms and improving quality of life. Therefore, dietary strategies should be individualized. This study compared the short term effects of low-fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAP) and gluten-free diets on symptom severity, health-related quality of life, dietary intake, and anthropometric measurements in individuals with IBS.

Materials and Methods: In this 3-arm, parallel-group randomized controlled trial, 63 adults diagnosed with IBS according to the Rome IV criteria were enrolled. Participants were randomly assigned to a low-FODMAP diet (n = 21), a gluten-free diet (n = 21), or a control group (n = 21). The intervention period lasted 4 weeks. Assessments were conducted at baseline and after the intervention using the IBS Symptom Severity Score (IBS-SSS), IBS Quality of Life questionnaire (IBS-QOL), IBS Visual Analog Scale, 3-day dietary intake records, and anthropometric measurements.

Results: Both intervention groups demonstrated reductions in IBS-SSS scores and improvements in IBS-QOL scores (P < .001). After adjustment for baseline values, a significant between-group difference was observed in quality of life (P < .001), whereas no significant difference was found in symptom severity (P > .05). Significant between-group differences were also observed in body weight, body mass index, waist circumference, waist-to-hip ratio, and carbohydrate intake.

Conclusion: Low-FODMAP and gluten-free diets may improve quality of life in individuals with IBS in the short term. After adjustment for baseline values, a between-group difference was observed only in quality of life, whereas no difference was found in symptom severity. These findings suggest that both dietary interventions may represent effective nutritional strategies for the management of IBS.

Cite this article as: Somtaş, AE, Çapar AG. A randomized controlled trial comparing low-FODMAP and gluten-free diets on gastrointestinal symptoms, nutritional status, and quality of life in irritable bowel syndrome. Turk J Gastroenterol. Published online June 25, 2026. doi:10.5152/tjg.2026.26147.