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NCT Number: NCT07688044

The Role That Food and Bacteria Play in Generating 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.

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Key information

Conditions

Irritable Bowel Syndrome (IBS) Abdominal Pain Colonic Diseases Colonic Diseases, Functional Digestive System Diseases Gastrointestinal Diseases Intestinal Diseases Irritable Bowel Syndrome Neurologic Manifestations Pain Pathological Conditions, Signs and Symptoms Signs and Symptoms Signs and Symptoms, Digestive

Age range

18 year–70 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Hotel Dieu Hospital

Kingston, Ontario, K7L 5G2, Canada

Location status: Recruiting

Location contact

Celine Morissette

CONTACT

[email protected]

(613) 449-5433

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

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

Exclusion criteria

  • Concurrent significant organic GI pathology (i.e. celiac, IBD, etc.) as some symptoms may be related to their disease and not IBS.
  • Concurrent systemic disease and/or laboratory abnormalities considered by investigators to be risky or that could interfere with data collection.
  • Major gastrointestinal surgery (e.g. Roux en y, bowel resection) as symptoms may be related to previous surgery rather than IBS.
  • Body mass index above 35 kg/m2 as it is unknown how mediators in the GI tract that may be involved in pain signaling in the gut are affected by obesity.
  • History of active cancer in the last 5 years, other than basal cell cancer as the treatment may have impacted the GI tract.
  • Pregnant or breastfeeding women.
  • Active or recent participation (< 1 month) in a clinical study.
  • Use of antibiotics, probiotics, during, or one month prior to the study as may affect gut microbiota.
  • Use of new medications less than 4 weeks prior to the study as may alter gut microbiota and/or IBS symptoms.
  • Allergies to any of the ingredients used in the study.
  • Any immune-compromising conditions as may affect GI symptoms.
  • 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.

Treatment and study plan

FODMAP Challenge

Other

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. 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.

Primary outcomes

  1. Change in Dorsal Root Ganglion (DRG) neuron rheobase by chemostat supernatant

    Time frame: 2-3 week of recording for each supernatant condition.

    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. Change in Dorsal Root Ganglion (DRG) neuron rheobase by fecal supernatant

    Time frame: 2-3 weeks for each supernatant condition

    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.

Secondary outcomes

  1. Irritable Bowel Syndrome (IBS) Symptom Severity Score

    Time frame: 6 weeks

    IBS Symptom Severity Score (a score of 0 to 500, with higher scores indicating greater symptom severity) will be taken at baseline, after low fodmap diet, each fodmap subtype challenge and glucose challenge. Change in IBS Symptom Severity Score as well as number of participants with a change of at least 50 points will be analyzed.

  2. Patient-Reported Outcomes Measurement Information System Belly Pain Score

    Time frame: 6 weeks

    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. The raw scores are 2-25 and this is converted to a standardized T score. Higher scores indicate a higher pain score.

  3. Microbial community composition

    Time frame: 6 weeks

    The chemostat cultures will be sampled after each stage (steady state, low fodmap media, fodmap subtype medias, glucose media) and analyzed

Sponsors and collaborators

Lead sponsor

David Reed

Other

Collaborators

  • Weston Family Foundation

Registry information

Official study title

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

Important dates

Study start
2026
Primary completion
2030
Study completion
2031
First posted
Jul 7, 2026
Registry last updated
Jul 15, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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