IBS-Oriented CDED Versus Low FODMAP Diet for Irritable Bowel Syndrome

Summary

Background: Irritable Bowel Syndrome (IBS) affects approximately 4.1% of the global population and imposes a significant personal and healthcare burden. Recent evidence highlights the role of low-grade inflammation, impaired intestinal permeability and gut microbiota dysbiosis in the pathophysiology of non-constipated IBS (IBS with predominate diarrhea; IBS-D and mixed type IBS; IBS-M). Most patients report food-related symptom exacerbation, making dietary intervention a cornerstone of treatment. While the low-FODMAP diet (LFD) is widely used to reduce fermentable carbohydrates and alleviate symptoms, it may negatively affect microbial diversity and lacks anti-inflammatory effects. In contrast, the Crohn's Disease Exclusion Diet (CDED), developed for Crohn's disease, has demonstrated the ability to reduce intestinal inflammation, improve barrier function, and promote a favorable microbiota profile. These mechanisms may be relevant and beneficial in IBS, but have yet to be studied in this population.

Objectives: To compare the efficacy of a modified CDED to the LFD for the treatment of non-constipated IBS symptoms, Hypothesis: A modified CDED will be at least as effective as the LFD in alleviating non-constipation IBS symptoms, stool consistency, quality of life, and psychological distress, while demonstrating superior effects on markers of low-grade inflammation, gut microbiota composition, and intestinal permeability.

Methods: This is a single-center, open-label, randomized study to be conducted at the Gastroenterology Department of Sheba Medical Center. 136 adults diagnosed with Rome IV-defined IBS-D or IBS-M and an IBS Symptom Severity Score (IBS-SSS) ≥175 will be randomized 1:1 to receive either a modified CDED or the LFD for 6 weeks. Accounting for a 10% dropout rate, the total sample size will be 150.

Following a 14-day screening period, eligible participants will undergo data collection at baseline, week 3 and week 6. Visit 1 (screening) will be conducted on-site; visits 2-4 will be remote. Participants will complete daily symptom diaries \[Bristol Stool Form Scale (BSFS) and GI Visual Analogue Scale (VAS)\], and weekly IBS-SSS. Validated questionnaires assessing psychological distress, somatization, extraintestinal symptoms, and quality of life will be administered at each time point.

Stool samples will be collected at baseline, week 3, and week 6. Fecal calprotectin (FC) and α1-Antitrypsin (A1AT) will be analyzed as markers of intestinal inflammation and permeability. Microbiota analysis will be conducted using 16S rRNA gene sequencing, with evaluation of microbial diversity, taxonomic shifts, and associations with clinical and biological outcomes.

Significance: This is the first study to evaluate the modified CDED as a dietary intervention for the treatment of IBS. It may offer a novel, inflammation-targeted alternative treatment for IBS.

Conditions

• Irritable Bowel Syndrome (IBS)

Interventions

OTHER

Modified Crohn's Disease Exclusion Diet (CDED)

Participants will follow a modified Crohn's Disease Exclusion Diet (CDED) adapted for patients with irritable bowel syndrome. The intervention excludes the enteral formula used in the original CDED protocol and is delivered for 6 weeks with individualized dietary counseling.

OTHER

Low FODMAP Diet

Participants will follow a standard low FODMAP diet for 6 weeks with individualized dietary counseling.

Sponsors & Collaborators

• Sheba Medical Center

  collaborator OTHER_GOV

• Ministry of Innovation, Science and Technology of Israel

  collaborator UNKNOWN

• Ariel University

  lead OTHER

Principal Investigators

• Keren Hod, RD PhD · Ariel University

Study Design

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

NONE

Model

PARALLEL

Eligibility

Min Age

18 Years

Sex

ALL

Healthy Volunteers

No

Timeline & Regulatory

Start

2026-07-07

Primary Completion

2028-07-30

Completion

2028-12-31