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

Not Applicable

Completed

• Conditions: Irritable Bowel Syndrome

• Registration Number: NCT04542018
• Lead Sponsor: University of Michigan

Brief Summary

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.

Detailed Description

Not available

Study Timeline

• Study Start: 2020-08-03
• Study First Submitted: 2020-09-01
• Study First Submitted QC: 2020-09-01
• Study First Posted: 2020-09-09
• Primary Completion: 2024-05-15
• Study Completion: 2024-05-15
• Results First Submitted: 2025-06-04
• Status Verified: 2025-07
• Results First Submitted QC: 2025-07-10
• Last Update Submitted: 2025-07-10
• Results First Posted: 2025-07-30
• Last Update Posted: 2025-07-30

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 48

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.

Exclusion Criteria

Not provided

Study & Design

• Study Type: INTERVENTIONAL
• Study Design: SINGLE_GROUP

Primary Outcome Measures

Name	Time	Method
Lactulose Mannitol Excretion	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 Outcome Measures

Name	Time	Method
Changes in Stool Microbiome - Alpha Diversity	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.
Immunohistochemistry for Mast Cells	4 weeks	Number of mast cells in sample after immunohistochemistry were counted.
Changes in Epithelial Permeability - Tight Junction Gene Expression	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).
Changes in Epithelial Permeability - Quantitative Tight Junction Immunostaining	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.
Gastrointestinal Patient Reported Outcomes Measurement Information System (PROMIS)	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.
Changes in Stool Microbiome - Beta Diversity	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

Trial Locations

Locations (2)

Beth Israel Deaconess Medical Center; 🇺🇸 Boston, Massachusetts, United States

University of Michigan; 🇺🇸 Ann Arbor, Michigan, United States