Low-FODMAP vs Gluten-Free Diet in Irritable Bowel Syndrome

NCT07800650 | Completed

• 1 other identifier: 2025-9-50
• Study Type: interventional
• Target: 70
• Locations: 1 country
• Sites: 1

Brief Summary

Irritable Bowel Syndrome (IBS) is a common functional gastrointestinal disorder characterized by recurrent abdominal pain and irregular bowel habits. Dietary interventions, particularly low-FODMAP and gluten-free diets, have gained increasing interest in IBS management. However, comparative data on these two approaches remain limited across different populations, including the Turkish population. This study was designed to compare the effectiveness of a 4-week low-FODMAP diet versus a gluten-free diet on gastrointestinal symptoms in Turkish patients with IBS. A total of 70 patients diagnosed with IBS according to Rome IV criteria were enrolled in this prospective, controlled, parallel-group clinical trial. Patients were sequentially assigned to either the low-FODMAP group (n=35) or the gluten-free diet group (n=35). Both dietary interventions were implemented over 4 weeks under the guidance of an experienced dietitian, with weekly telephone follow-ups to monitor dietary compliance. Gastrointestinal symptoms were evaluated at baseline and at the end of the intervention using the Gastrointestinal Symptom Rating Scale (GSRS).

Conditions

Irritable Bowel Syndrome

Keywords

Irritable Bowel Syndrome; low-FODMAP diet; gluten-free diet

Outcome Measures

Primary Outcomes (1)

• Change in Total GSRS Score

  Change in the total Gastrointestinal Symptom Rating Scale (GSRS) score from baseline to 4 weeks. The GSRS is a 15-item scale with total scores ranging from 15 to 105. Higher scores indicate more severe gastrointestinal symptoms.

  Baseline and 4 weeks

Secondary Outcomes (5)

• Change in GSRS Diarrhea Subscale Score

  Baseline and 4 weeks

• Change in GSRS Indigestion Subscale Score

  Baseline and 4 weeks

• Change in GSRS Constipation Subscale Score

  Baseline and 4 weeks

• Change in GSRS Abdominal Pain Subscale Score

  Baseline and 4 weeks

• Change in GSRS Reflux Subscale Score

  Baseline and 4 weeks

Study Arms (2)

Low-FODMAP Diet Group

EXPERIMENTAL

Participants followed a low-FODMAP diet for 4 weeks under the guidance of an experienced dietitian.

Other: Low-FODMAP Diet

Gluten-Free Diet Group

EXPERIMENTAL

Participants followed a strict gluten-free diet for 4 weeks under the guidance of an experienced dietitian.

Other: Gluten-Free Diet

Interventions

Gluten-Free Diet OTHER

Participants were instructed to exclude gluten-containing grains (wheat, barley, rye) and their derivatives (bread, pasta, pastries), and to consume naturally gluten-free foods (rice, corn, potatoes, meat, vegetables, fruits). The diet was applied for 4 weeks.

Gluten-Free Diet Group

Low-FODMAP Diet OTHER

Participants were instructed to limit foods high in FODMAPs (onions, garlic, pulses, certain fruits and vegetables, wheat products) and to consume low-FODMAP alternatives (rice, oats, potatoes, carrots, bananas). The diet was applied for 4 weeks.

Low-FODMAP Diet Group

Eligibility Criteria

• Age: 18 Years - 65 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Diagnosed with Irritable Bowel Syndrome (IBS) according to the Rome IV diagnostic criteria
• Aged between 18 and 65 years
• Literate
• Signed the informed consent form

You may not qualify if:

• Psychiatric or neurological condition affecting cooperation (dementia, psychosis, etc.)
• Chronic condition (celiac disease, inflammatory bowel disease, diabetes, chronic kidney failure, liver failure, malignancy)
• Regular use of medication for IBS symptoms (antispasmodics, loperamide, laxatives, antidepressants, etc.)
• Eating disorder (anorexia nervosa, bulimia nervosa, etc.)
• Malabsorption syndrome preventing adherence to the diet
• Pregnancy or breastfeeding

Sponsors & Collaborators

• Ertuğrul Çoruh: lead

Study Sites (1)

Yıldızkent Family Health Center

Erzurum, 25080, Turkey (Türkiye)

Location

MeSH Terms

Conditions

Irritable Bowel Syndrome

Interventions

FODMAP Diet; Diet, Gluten-Free

Condition Hierarchy (Ancestors)

Colonic Diseases, Functional; Colonic Diseases; Intestinal Diseases; Gastrointestinal Diseases; Digestive System Diseases

Intervention Hierarchy (Ancestors)

Elimination Diets; Diet; Nutritional Physiological Phenomena; Diet, Food, and Nutrition; Physiological Phenomena; Diet Therapy; Nutrition Therapy; Therapeutics

Study Officials

• Ertuğrul Çoruh, MD

  Yıldızkent Family Health Center, Palandöken District Health Directorate, Erzurum, Turkey

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NON RANDOMIZED
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: SPONSOR INVESTIGATOR
• PI Title: Family Physician

Model Details: Participants were assigned to one of two parallel dietary intervention groups

Study Record Dates

• First Submitted: August 25, 2026
• First Posted: September 2, 2026
• Study Start: December 24, 2025
• Primary Completion: July 20, 2026
• Study Completion: July 25, 2026
• Last Updated: September 2, 2026

Record last verified: 2026-08

Data Sharing

• IPD Sharing: Will not share

Locations

TU (1)