The Role That Food and Bacteria Play in Generating Abdominal Pain

The Role of Gut Microbiota in Patient Responses to a Dietary Therapy for Abdominal Pain

Irritable Bowel Syndrom (IBS) affects up to five percent of Canadians and has proven difficult to treat. Our research will explore how a type of dietary carbohydrate, called FODMAPS, contributes to chronic abdominal pain in irritable bowel syndrome (IBS). FODMAPs, are poorly digested carbohydrates and removing FODMAPs from the diet relieves abdominal pain in approximately half of IBS patients. Unfortunately, FODMAPs are contained in many foods, which makes it challenging for patients to remain on a low FODMAP diet for extended periods. Our proposed research will identify which subtypes of FODMAPs are most responsible for increasing pain and will tease apart whether the pain-causing effects of FODMAPs rely on the gut microbiota or not. To identify which specific type of FODMAP causes pain, IBS patients will adopt a low FODMAP diet and then individual FODMAP subtypes will be added back to their diet while monitoring changes to their pain. Stool samples will be collected from the participants to determine whether the composition of the gut microbiota or the chemicals that it produces are changed when symptoms are improved or exacerbated by manipulating FODMAP availability. In parallel studies, the microbiota of each IBS patient will be grown in specialized conditions to mimic the environment of the gut. These patient microbial communities will be exposed to the same FODMAP manipulations as the patients themselves experience. This will allow us to test whether the changes in gut microbiota composition and the chemicals produced that occur in IBS patients in response to FODMAP manipulations also occur when only the microbiota is exposed to these manipulations. Together, these studies will aim to optimize a dietary therapy for a common chronic pain condition and will provide novel insights into how diet affects the chemicals the gut microbiota produces that contribute to abdominal pain.

Study Overview

• Status: Recruiting
• Conditions: Irritable Bowel Syndrome (IBS)
• Intervention / Treatment: Other: FODMAP Challenge

• Study Type: Interventional
• Enrollment (Estimated): 60
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Canada
  • Ontario
    • Kingston, Ontario, Canada, K7L 5G2
      • Recruiting
      • Hotel Dieu Hospital
      • Contact: Celine Morissette; Phone Number: (613) 449-5433; Email: celine.morissette@kingstonhsc.ca

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Adults aged 18-70 with IBS (Rome IV (now V) criteria)
• PROMIS belly pain score >12

Exclusion Criteria:

1. Concurrent significant organic GI pathology (i.e. celiac, IBD, etc.) as some symptoms may be related to their disease and not IBS.
2. Concurrent systemic disease and/or laboratory abnormalities considered by investigators to be risky or that could interfere with data collection.
3. Major gastrointestinal surgery (e.g. Roux en y, bowel resection) as symptoms may be related to previous surgery rather than IBS.
4. Body mass index above 30 kg/m2 as it is known how mediators in the GI tract that may be involved in pain signaling in the gut are affected by obesity.
5. History of active cancer in the last 5 years, other than basal cell cancer as the treatment may have impacted the GI tract.
6. Pregnant or breastfeeding women.
7. Active or recent participation (< 1 month) in a clinical study.
8. Use of antibiotics, probiotics, during, or one month prior to the study as may affect gut microbiota.
9. Use of new medications less than 4 weeks prior to the study as may alter gut microbiota and/or IBS symptoms.
10. Allergies to any of the ingredients used in the study.
11. Any immune-compromising conditions as may affect GI symptoms.
12. Currently being treated for eating disorder, schizophrenia, psychosis or other acute mental disorders as participating in a diet challenge study may have negative impact on these disorders.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm

Intervention / Treatment

Experimental: FODMAP Challenge; Participants will be on a low fodmap diet (LFD) for a total of 6 weeks b. After two weeks on LFD, each participant whose IBS-symptom severity score was reduced by 50 points will be deemed a responder, and will proceed to the next stage of the study, which will entail each participant remaining on the LFD while beginning 4 four-day individual challenges every 7 days consisting of 3 FODMAP subgroup challenges (galacto-oligosaccahrides, fructan, and sorbitol) and 1 glucose challenge as a non-FODMAP carbohydrate control. Each challenge will comprise of a 4-day challenge with one of the three FODMAP subgroups listed below or a glucose challenge (as a negative control) followed by a 3-day washout period with any residual symptoms resolved while remaining on the LFD prior to the next challenge

Other: FODMAP Challenge; Prior to beginning the LFD, each participant will provide a stool sample. This will be used to inoculate a continuous culture system (chemostat) as these vessels maintain fecal microbial communities under controlled anaerobic conditions. After reaching steady state in culture media with FODMAPs (7 days), the media will be switched to a low FODMAP media for 7 days. Then each vessel will be exposed to the same FODMAP subgroups challenges and glucose challenge as the participants for 3 days followed by 3 day challenge. At each stage (i.e., steady state, after low fodmap media, after each challenge) culture supernatant will be collected. This supernatant will be used to test its neurophysiological effects on pain sensing neurons in pre-clinical studies. In addition, participants will provide a stool sample at each stage. Fecal supernatants will be produced from these samples and the neurophysiological effects of the fecal supernatants will be tested in pre-clinical studies.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in DRG neuron rheobase by chemostat supernatant	DRG neurons will be incubated overnight with chemostat supernatant after steady state, low fodmap media, fodmap subtype media and glucose media. Patch clamp recordings will be made from neurons the following day the rheobase (minimum current required to elicit an action potential in a neuron) will be measured. The mean rheobase for neurons exposed to the different supernatant conditions will be compared.	2-3 week of recording for each supernatant condition.
Change in DRG neuron rheobase by fecal supernatant	DRG neurons will be incubated overnight with fecal supernatant at baseline, after low fodmap diet, fodmap subtype challenge and glucose challenge. Patch clamp recordings will be made from neurons the following day the rheobase (minimum current required to elicit an action potential in a neuron) will be measured. The mean rheobase for neurons exposed to the different supernatant conditions will be compared.	2-3 weeks for each supernatant condition

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
IBS Symptom Severity Score	IBS-SSS will be taken at baseline, after low fodmap diet, each fodmap subtype challenge and glucose challenge. Change in IBS-SSS as well as number of participants with a change of at least 50 points will be analyzed.	6 weeks
PROMIS Belly Pain Score	These questionnaires will be administered at baseline, after low fodmap diet, each fodmap subtype challenge and glucose challenge. The scores at each time point will be compared.	6 weeks
Microbial community composition	The chemostat cultures will be sampled after each stage (steady state, low fodmap media, fodmap subtype medias, glucose media) and analyzed	6 weeks

Collaborators and Investigators

• Sponsor: David Reed
• Collaborators: Weston Family Foundation

Study record dates

Study Major Dates

• Study Start (Actual): March 16, 2026
• Primary Completion (Estimated): March 1, 2030
• Study Completion (Estimated): March 1, 2031

Study Registration Dates

• First Submitted: June 30, 2026
• First Submitted That Met QC Criteria: June 30, 2026
• First Posted (Actual): July 7, 2026

Study Record Updates

• Last Update Posted (Actual): July 7, 2026
• Last Update Submitted That Met QC Criteria: June 30, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Keywords: Microbiota; Abdominal pain; FODMAPs; Neuroactive mediators; GI pain signaling
• Additional Relevant MeSH Terms: Pain; Neurologic Manifestations; Signs and Symptoms, Digestive; Intestinal Diseases; Digestive System Diseases; Gastrointestinal Diseases; Colonic Diseases; Colonic Diseases, Functional; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Irritable Bowel Syndrome; Abdominal Pain
• Other Study ID Numbers: 6044324

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No