Dietary Interventions for Irritable Bowel Syndrome

NCT07774923 | Completed

• 1 other identifier: 78097791-020-3735
• Study Type: interventional
• Target: 60
• Locations: 1 country
• Sites: 1

Brief Summary

Irritable bowel syndrome (IBS) is a disorder of gut-brain interaction characterized by recurrent abdominal pain and altered bowel habits. Dietary factors may trigger or worsen symptoms such as abdominal pain, bloating, gas, diarrhea, and constipation. This study evaluated and compared the effects of a low-fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (low-FODMAP) diet and a combined gluten-free and lactose-free diet on symptom severity in adults diagnosed with IBS. Adults aged 19-64 years with IBS followed one of the two dietary interventions for six weeks. IBS symptom severity was assessed at baseline and at the end of week 6 using the Irritable Bowel Syndrome Symptom Severity Score (IBS-SSS). Dietary adherence was monitored by telephone during the intervention.

Conditions

Irritable Bowel Syndrome

Keywords

Low-FODMAP Diet; Gluten-Free Diet; Lactose-Free Diet; Dietary Intervention; Gastrointestinal Symptoms; IBS Symptom Severity Score

Outcome Measures

Primary Outcomes (1)

• Change From Baseline in Irritable Bowel Syndrome Symptom Severity Score at Week 6

  The Irritable Bowel Syndrome Symptom Severity Score (IBS-SSS) was used to assess overall IBS symptom severity. The instrument includes five domains: abdominal pain severity, frequency of abdominal pain, abdominal bloating severity, satisfaction with bowel habits, and interference of bowel symptoms with daily life. The total score ranges from 0 to 500, with higher scores indicating greater symptom severity. Change was calculated as the week 6 score minus the baseline score; a negative change indicates improvement.

  Baseline and Week 6

Secondary Outcomes (5)

• Change From Baseline in Abdominal Pain Severity at Week 6

  Baseline and Week 6

• Change From Baseline in Abdominal Pain Frequency at Week 6

  Baseline and Week 6

• Change From Baseline in Abdominal Bloating Severity at Week 6

  Baseline and Week 6

• Change From Baseline in Dissatisfaction With Bowel Habits at Week 6

  Baseline and Week 6

• Change From Baseline in Interference of Bowel Symptoms With Daily Life at Week 6

  Baseline and Week 6

Study Arms (2)

Low-FODMAP Diet

EXPERIMENTAL

Participants followed a low-FODMAP diet for six weeks. The intervention restricted foods high in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols. Dietary adherence was monitored by telephone during the intervention.

Behavioral: Low-FODMAP Diet

Gluten-Free and Lactose-Free Diet

ACTIVE COMPARATOR

Participants followed a combined gluten-free and lactose-free diet for six weeks. The intervention excluded foods containing gluten and lactose. Dietary adherence was monitored by telephone during the intervention.

Behavioral: Gluten-Free and Lactose-Free Diet

Interventions

Low-FODMAP Diet BEHAVIORAL

Participants followed a low-FODMAP diet for six weeks. Foods high in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols were restricted. Participants received detailed dietary instructions during the initial face-to-face visit. Dietary adherence was monitored by telephone one week after starting the intervention and subsequently at two-week intervals.

Also known as: Low Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols Diet

Low-FODMAP Diet

Gluten-Free and Lactose-Free Diet BEHAVIORAL

Participants followed a combined gluten-free and lactose-free diet for six weeks. Foods containing gluten and lactose were excluded. Participants received detailed dietary instructions during the initial face-to-face visit. Dietary adherence was monitored by telephone one week after starting the intervention and subsequently at two-week intervals.

Also known as: Combined Gluten-Free and Lactose-Free Diet

Gluten-Free and Lactose-Free Diet

Eligibility Criteria

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

You may qualify if:

• Adults aged 19-64 years
• Diagnosed with irritable bowel syndrome
• Male or female
• Provided written informed consent to participate in the study

You may not qualify if:

• Pregnancy or lactation
• Diagnosis of cancer
• Presence of a gastrointestinal disease other than irritable bowel syndrome
• Diagnosis of diabetes mellitus
• Diagnosis of a psychiatric disorder

Sponsors & Collaborators

• Istanbul Gelisim University: lead
• Mersin University: collaborator
• Bahçeşehir University: collaborator

Study Sites (1)

Mersin University Hospital

Mersin, 33343, Turkey (Türkiye)

Location

MeSH Terms

Conditions

Irritable Bowel Syndrome

Interventions

FODMAP Diet; Disaccharides; Monosaccharides; 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; Oligosaccharides; Polysaccharides; Carbohydrates; Sugars; Diet Therapy; Nutrition Therapy; Therapeutics

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Masking Details: No masking was applied because participants and researchers were aware of the assigned dietary intervention.
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Model Details: Participants followed one of two dietary interventions for six weeks: a low-FODMAP diet or a combined gluten-free and lactose-free diet. Each participant remained in the same intervention arm throughout the study, with no crossover between arms.

Study Record Dates

• First Submitted: August 15, 2026
• First Posted: August 19, 2026
• Study Start: February 25, 2025
• Primary Completion: July 18, 2025
• Study Completion: July 18, 2025
• Last Updated: August 20, 2026

Record last verified: 2026-08

Data Sharing

• IPD Sharing: Will not share

Locations

TU (1)