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Completed

NCT Number: NCT04542018

Effects of Low FODMAP Diet on Colonic Epithelial Physiology in Diarrhea-predominant Irritable Bowel Syndrome

This research is studying whether changing an individual's diet may have an impact as a treatment or outcome for Irritable Bowel Syndrome (IBS). This research will show if diet might play a role in triggering changes that may cause IBS. This study is being done to learn if a low FODMAP (fermentable, oligosaccharides, disaccharides, monosaccharides, and polyols) diet causes changes in the colon lining which mediates improvement in IBS symptoms.

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Key information

Conditions

Irritable Bowel Syndrome Colonic Diseases Colonic Diseases, Functional Digestive System Diseases Gastrointestinal Diseases Intestinal Diseases

Age range

18 year–65 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Beth Israel Deaconess Medical Center, Boston, Massachusetts, United States

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Who can participate

Healthy volunteers accepted: No

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

Inclusion criteria

  • Normal serum studies including serum tissue-transglutaminase antibodies, thyroid stimulating hormone levels, C-reactive protein or fecal calprotectin, complete blood count since the onset of symptoms.
  • Normal stool studies including, ova and parasites since the onset of symptoms
  • IBS-SSS score of ≥175 at the end of the 7-day screening period

In case of presence of any alarm features and/or elevated inflammatory markers (C-reactive protein or fecal calprotectin), patients will be eligible if they have been excluded for inflammatory bowel disease with colonoscopy in the last one year.

Exclusion criteria

  • individuals already on a LFD or other dietary restriction such as gluten free diet within the past 6 months
  • individuals with any known food allergy or insulin-dependent diabetes
  • known history of celiac disease, inflammatory bowel disease or microscopic colitis
  • prior small bowel or colonic surgery or cholecystectomy
  • pregnant patients
  • Antibiotics in the past 3 months
  • Those who regularly use mast cell stabilizers or anti-histaminic or non-steroidal anti-inflammatory agents (NSAIDs) excluding daily baby aspirin or steroids or bile-acid binder.

Treatment and study plan

a low FODMAP diet for 4 weeks

Other

low FODMAP diet for 4 weeks

Primary outcomes

  1. Lactulose Mannitol Excretion

    Time frame: 4 weeks

    Changes in cumulative excretion of lactulose and mannitol in timed urine collection before and after low FODMAP diet measured during 8-24h

Secondary outcomes

  1. Changes in Epithelial Permeability - Tight Junction Gene Expression

    Time frame: 4 weeks

    Changes in tight junction (TJ) gene expression in colonic biopsies before and after low FODMAP diet Gene expression of Tight junction proteins were normalized to that of Glyceraldehyde 3-phosphate dehydrogenase (GAPDH).

  2. Changes in Epithelial Permeability - Quantitative Tight Junction Immunostaining

    Time frame: 4 weeks

    Changes in Quantitative tight junction immunostaining of tight junctions in colonic biopsies before and after low FODMAP diet

    Data is reported as ratio of TJ proteins to NA-K ATPase.

  3. Changes in Stool Microbiome - Alpha Diversity

    Time frame: 4 weeks

    Changes in relative abundance of bacteria before and after low FODMAP diet. Alpha diversity was measured as number of Amplicon Sequence Variant (ASV) measured in the specimen.

  4. Changes in Stool Microbiome - Beta Diversity

    Time frame: 4 weeks

    Changes in relative abundance of bacteria before and after low FODMAP diet. For the beta diversity, an analysis of similarities (ANOSIM)test based on Bray-Curtis distances is the best measure if the communities were different. The ANOSIM R statistic gives the scale of difference. ANOSIM R ranges from -1 to 1, where 1 means there is most interparticipant similarity within the group compared with between the different groups, and where -1 means there is least interparticipant similarity within the group compared with between the different groups. A value close to 0 indicates no significant difference between groups, meaning the dissimilarity is similar both within and between groups

  5. Immunohistochemistry for Mast Cells

    Time frame: 4 weeks

    Number of mast cells in sample after immunohistochemistry were counted.

  6. Gastrointestinal Patient Reported Outcomes Measurement Information System (PROMIS)

    Time frame: 4 weeks

    PROMIS scales of Belly pain (5a) and diarrhea (6a) will be administered to assess the severity of belly pain and diarrhea in our patients. PROMIS Belly pain questionnaire and PROMIS diarrhea questionnaire have five and six questions, respectively, which assess symptom severity on a 5 point Likert scale. 50 indicates the general population mean with a standard deviation of 10. Higher T-scores on these questionnaires refer to more severe gastrointestinal symptoms.

    PROMIS belly pain asks how often did you have belly pain, severity of belly pain, interference with activities, bothersomeness and discomfort.

    PROMIS diarrhea asks how many days did you have loose stools, interference with activities, bothersomeness, and how often you experience urgency.

Other outcomes

  1. Irritable Bowel Syndrome Severity Scoring System (IBS-SSS) - 4-Week

    Time frame: 4 weeks

    Measure Description: IBS-SSS is a scale for assessing overall IBS symptom severity. It includes 5 questions concerning symptoms over the past 10 days: average severity of abdominal pain, # of days with abdominal pain, average severity of abdominal distension or bloating, satisfaction with bowel habits, and the overall interference in their quality of life from these symptoms. Questions are scored on a 0-100 scale and are summed to a total score between 0-500. Lower scores indicate lower symptom severity.

    Participants were separated into arms based on the change in their responses from baseline to 4 weeks.

Sponsors and collaborators

Lead sponsor

University of Michigan

Other

Collaborators

  • National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)

Registry information

Important dates

Study start
2020
Primary completion
2024
Study completion
2024
First posted
Sep 9, 2020
Registry last updated
Jul 30, 2025

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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