Low-FODMAP vs Lactose-Gluten-Free Diet in Patients With Irritable Bowel Syndrome

NCT07722572 | Completed DMC

• 1 other identifier: 2020/034
• Study Type: interventional
• Target: 72
• Locations: 1 country
• Sites: 1

Brief Summary

Irritable bowel syndrome (IBS) is a common functional gastrointestinal disorder that substantially affects quality of life. Dietary therapy is considered one of the primary treatment approaches; however, the optimal sequence of dietary interventions remains unclear. This randomized crossover trial was designed to compare the effects of a low-FODMAP diet and a lactose-free, gluten-free diet on gastrointestinal symptoms, psychological status, anthropometric measurements, and biochemical parameters in adults with IBS. Participants were randomly assigned to one of two dietary sequences, with each intervention lasting four weeks and separated by a one-week washout period. Outcomes were assessed using validated symptom and psychological questionnaires together with anthropometric and biochemical measurements before and after each intervention period.

Conditions

Irritable Bowel Syndrome

Keywords

Anxiety; Irritable Bowel Syndrome; Diet; FODMAPs; Lactose-free and gluten-free diet

Outcome Measures

Primary Outcomes (1)

• Change in Irritable Bowel Syndrome Symptom Severity Score (IBS-SSS)

  Change in Irritable Bowel Syndrome Symptom Severity Score (IBS-SSS). The IBS Symptom Severity Score assessed the severity of IBS symptoms based on four questions, scoring between 0 and 100 points for each symptom. A total score of 75-174 points indicated mild IBS, 175-299 points indicated moderate IBS, and \>300 points indicated severe IBS.

  Baseline, Week 4, and Week 9

Secondary Outcomes (4)

• Change in Gastrointestinal Symptom Rating Scale (GSRS) score

  Baseline, Week 4, and Week 9

• Change in Hospital Anxiety and Depression Scale (HADS) score

  Baseline, Week 4, and Week 9

• Change in body weight

  Baseline, Week 4, and Week 9

• Change in body mass index

  Baseline, Week 4, and Week 9

Study Arms (2)

Low-FODMAP → Lactose- and Gluten-Free Diet

EXPERIMENTAL

Participants received the low-FODMAP diet for 4 weeks, followed by a 1-week washout period and then the lactose- and gluten-free diet for 4 weeks.

Behavioral: Low-FODMAP Diet; Behavioral: Lactose- and Gluten-Free Diet

Lactose- and Gluten-Free Diet → Low-FODMAP

EXPERIMENTAL

Participants received the lactose- and gluten-free diet for 4 weeks, followed by a 1-week washout period and then the low-FODMAP diet for 4 weeks.

Behavioral: Low-FODMAP Diet; Behavioral: Lactose- and Gluten-Free Diet

Interventions

Low-FODMAP Diet BEHAVIORAL

Participants followed a low-FODMAP diet for 4 weeks under the supervision of a dietitian.

Lactose- and Gluten-Free Diet → Low-FODMAP; Low-FODMAP → Lactose- and Gluten-Free Diet

Lactose- and Gluten-Free Diet BEHAVIORAL

Participants followed a lactose- and gluten-free diet for 4 weeks under the supervision of a dietitian.

Lactose- and Gluten-Free Diet → Low-FODMAP; Low-FODMAP → Lactose- and Gluten-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 18-64 years.
• Diagnosis of Irritable Bowel Syndrome according to the Rome III criteria.
• Ability and willingness to comply with the dietary intervention.
• Written informed consent provided.

You may not qualify if:

• Pregnancy or lactation.
• Diabetes mellitus.
• Organic gastrointestinal disease.
• Current follow-up for cardiologic, neurologic, oncologic, or psychiatric disorders.
• Following a therapeutic diet within 1 month before enrollment.

Sponsors & Collaborators

• Antalya Bilim University: lead

Study Sites (1)

Istanbul University-Cerrahpaşa, Cerrahpaşa Faculty of Medicine, Department of Gastroenterology

Istanbul, Turkey (Türkiye)

Location

MeSH Terms

Conditions

Irritable Bowel Syndrome; Anxiety Disorders

Interventions

FODMAP Diet; Lactose; Diet, Gluten-Free

Condition Hierarchy (Ancestors)

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

Intervention Hierarchy (Ancestors)

Elimination Diets; Diet; Nutritional Physiological Phenomena; Diet, Food, and Nutrition; Physiological Phenomena; Disaccharides; Oligosaccharides; Polysaccharides; Carbohydrates; Sugars; Diet Therapy; Nutrition Therapy; Therapeutics

Study Officials

• Hatice Kübra Aras

  Antalya Bilim University

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Model Details: Participants were randomized to two crossover sequences. Each participant received both dietary interventions (low-FODMAP diet and lactose- and gluten-free diet) for 4 weeks each, separated by a 1-week washout period.

Study Record Dates

• First Submitted: July 16, 2026
• First Posted: July 23, 2026
• Study Start: September 1, 2020
• Primary Completion: November 25, 2021
• Study Completion: January 20, 2022
• Last Updated: July 23, 2026

Record last verified: 2026-07

Data Sharing

• IPD Sharing: Will not share

Locations

TU (1)