Investigating how diet affects gut bacteria in irritable bowel syndrome

Biomarkers of Diet-microbiota Interactions in Irritable Bowel Syndrome

Early Phase 1 Interventional McMaster University · NCT04364750

This study is testing how a low-FODMAP diet and different drinks affect gut bacteria in people with irritable bowel syndrome to see if it can help improve their symptoms.

Quick facts

PhaseEarly Phase 1
Study typeInterventional
Enrollment30 (estimated)
Ages18 Years to 75 Years
SexAll
SponsorMcMaster University Academic / other
Locations2 sites (Hamilton, Ontario and 1 other locations)
Trial IDNCT04364750 on ClinicalTrials.gov

What this trial studies

This study aims to explore the relationship between dietary intake, specifically FODMAPs, and the production of histamine by gut bacteria in patients with irritable bowel syndrome (IBS). Participants will follow a low-FODMAP diet for six weeks, during which they will receive either high- or low-FODMAP beverages along with probiotics or placebo capsules. The study will analyze the participants' gut bacteria and metabolites at various time points to understand how these factors contribute to IBS symptoms. The goal is to identify biomarkers that could help tailor dietary recommendations for IBS patients.

Who should consider this trial

Good fit: Ideal candidates include adults aged 18-75 with IBS who have previously experienced symptom improvement on a low-FODMAP diet.

Not a fit: Patients with significant organic gastrointestinal pathology or systemic diseases that could interfere with the study may not benefit from this research.

Why it matters

Potential benefit: If successful, this study could lead to more personalized dietary interventions for IBS patients, improving their symptom management.

How similar studies have performed: Previous studies have indicated that dietary modifications can significantly impact IBS symptoms, suggesting potential success for this approach.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

* Adults aged 18-75 with IBS (Rome IV criteria) who have self-reported previous improvement in their IBS symptoms while on a low FODMAP diet, or when excluding certain high-FODMAP foods, or patients in whom histamine is expected to play a key role (either diagnosed with high histamine producing bacteria, or improved IBS symptoms after using antihistamines). Individuals should be able to swallow size 00 capsules.

Exclusion Criteria:

* Concurrent significant organic GI pathology (i.e. celiac, IBD, etc.)
* Concurrent systemic disease (such as diabetes) and/or laboratory abnormalities considered by investigators to be risky or that could interfere with data collection
* History of active cancer in the last 5 years, other than basal cell cancer
* Pregnant or breastfeeding women
* Active or recent participation (\< 1 month) in a clinical study, except for SPOR IMAGINE
* Use of antibiotics, probiotics, or ACE inhibitors during, or one month prior to the study
* Use of new medications less than 4 weeks prior to the study.
* Allergies to any of the ingredients used in the study
* Any immune-compromising conditions

Where this trial is running

Hamilton, Ontario and 1 other locations

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions Irritable Bowel SyndromeFODMAPmicrobiotahistamine
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.