Evaluating the Efficacy of the Mediterranean Diet to the Low- Fermentable, Oligosaccharides, Disaccharides, Monosaccharides, and Polyols (FODMAP) Diet in Treating Irritable Bowel Syndrome(IBS)

Evaluate and Compare the Clinical Efficacy of the Mediterranean Diet to the Low-FODMAP Diet in Treating Irritable Bowel Syndrome

This study is being completed to determine if the Mediterranean (MD) and low FODMAP (fermentable, oligosaccharides, disaccharides, monosaccharides, and polyols) diets are comparable in the effectiveness to treat Irritable Bowel Syndrome (IBS).

The study team hypothesizes that:

• The low FODMAP and Mediterranean groups will achieve a similar improvement in abdominal pain
• Both groups will achieve similar improvements in bloating, overall IBS symptom severity, and adequate relief

Study Overview

• Status: Completed
• Conditions: Irritable Bowel Syndrome
• Intervention / Treatment: Other: Diet low in all FODMAP groups; Other: Diet - Mediterranean

• Study Type: Interventional
• Enrollment (Actual): 26
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Michigan
    • Ann Arbor, Michigan, United States, 48109
      • University of Michigan

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

• Patients with IBS-D (diarrhea-predominant IBS) or IBS-M (IBS with mixed subtype) diagnosed per Rome IV questionnaire and without any unexplained alarm features (rectal bleeding, weight loss, nocturnal symptoms, personal history of celiac disease, microscopic colitis, inflammatory bowel disease)
• Aged 18-70 years at the time of screening
• Weekly average of worst daily (in the past 24 hours) abdominal pain score of ≥3.0 on a 0-to-10-point scale
• At least 80 percent compliance in daily questionnaire entries during the 7-day screening period

Exclusion Criteria:

• Subjects adhering to any dietary IBS treatment such as the low-fodmap diet, or gluten-free diet, Mediterranean currently or within the past 6 months
• Subjects with a known food allergy to eggs, seafood, peanuts, tree nuts or milk (subjects with lactose intolerance that are experiencing IBS symptoms while on a lactose-free diet will not be excluded from the study).
• Subjects with a history of poorly controlled insulin-dependent or non-insulin-dependent diabetes
• Subjects with a known history of organic Gastrointestinal (GI) disease (i.e., celiac disease, inflammatory bowel disease or microscopic colitis)
• Subjects with a history of an eating disorder requiring medical or behavioral treatment within the past 10 years.
• Subjects with prior small bowel or colonic surgery (excluding appendectomy or cholecystectomy if over 6 months since these 2 procedures)
• Oral antibiotic use in the past 3 months
• Any planned significant changes in dietary or exercise regimen within 30 days prior to Screening or during the study.
• Currently pregnant or breastfeeding.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Diet low in all FODMAP groups	Other: Diet low in all FODMAP groups; Randomized participants will eat this diet for 4 weeks (all meals and snacks will be provided). Participants will only eat the study food for this intervention. Participants will be asked to complete surveys, food diaries, and have blood and stools samples pre and post treatment.
Experimental: Diet - Mediterranean	Other: Diet - Mediterranean; Randomized participants will eat this diet for 4 weeks (all meals and snacks will be provided). Participants will only eat the study food for this intervention. Participants will be asked to complete surveys, food diaries, and have blood and stools samples pre and post treatment.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Proportion of Participants Who Are Responders Based on the Abdominal Pain Intensity Score for at Least 2 of 4 Weeks	Results reflect the participants who were weekly responders for at least 2 of the 4 weeks based on their abdominal pain intensity score. The abdominal pain score was a single-question, 11-point numeric rating scale in which 0 represented no abdominal pain and 11 represented the worst possible abdominal pain. Once per day, subjects reported their worst daily (in the past 24 hours) abdominal pain. A weekly responder was defined as a participant whose score decreased in the weekly average of worst abdominal pain in the past 24 hours by at least 30% compared with baseline.	4 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Proportion of Participants Who Are Weekly Responders to Adequate Relief Symptom Assessment for at Least 2 of 4 Weeks	Results reflect the participants who were weekly responders based on the adequate relief symptom assessment for at least 2 of the 4 weeks. Participants provided a binary (yes or no) response to rate the adequacy of relief of global irritable bowel syndrome (IBS) symptoms at the start of the study and weekly thereafter. A weekly responder was defined as a participant who achieved adequate relief in symptoms in at least 2 out of 4 weeks of the treatment period.	4 weeks
Proportion of Participants Who Are Weekly Responders Based on the Irritable Bowel Severity Scoring System (IBS-SSS) Modified Version for at Least 2 of the 4 Weeks	Results reflect participants who were weekly responders for at least 2 of the 4 weeks based on their scores on a modified version of the IBS-SSS. This version of the IBS-SSS was comprised of 5 questions participants answered based on their stomach and bowels. The total score for this modified version of the IBS-SSS was 0-500, with 0 indicating no IBS symptoms and 500 indicating the highest amount of IBS symptoms. A weekly responder was defined as a participant whose score decreased in the weekly IBS-SSS by at least 50 points compared with baseline.	4 weeks
Change in Mean Score of the Irritable Bowel Severity Scoring System (IBS-SSS) Modified Version	The modified version of the IBS-SSS was comprised of 5 questions participants answered based on their stomach and bowels. The total score for this modified version of the IBS-SSS was 0-500, with 0 indicating no IBS symptoms and 500 indicating the highest amount of IBS symptoms. The results represent the mean change from baseline minus 4 weeks.	Baseline, 4 weeks
Proportion of Participants Who Are Weekly Responders to Bloating for at Least 2 of the 4 Weeks	Results reflect the number of participants who were weekly responders based on their abdominal bloating score for at least 2 of 4 weeks. The abdominal bloating score was a single-question, 11-point numeric rating scale in which 0 represented no abdominal bloating and 11 represented the worst possible abdominal bloating. Once per day, participants reported their worst daily (in the past 24 hours) abdominal bloating. A weekly responder was defined as a participant whose score decreased in the weekly average of worst bloating in the past 24 hours by at least 30% compared with baseline.	4 weeks
Participants Who Are Weekly Responders to Stool Consistency Based on the Bristol Stool Scale (BSS) for at Least 2 of the 4 Weeks	Results reflect the participants who were weekly responders based on their stool consistency assessment for at least 2 of 4 weeks. A stool consistency weekly responder was defined as a participant with a 50% or greater reduction in the number of days per week with at least one abnormal stool. Stools that scored as 1 or 2 (hard stool) or 6 or 7 (liquid stool) on the BSS were defined as abnormal.	4 weeks

Collaborators and Investigators

• Sponsor: University of Michigan
• Collaborators: National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK); ModifyHealth
• Investigators: Principal Investigator: Prashant Singh, MD, University of Michigan

Study record dates

Study Major Dates

• Study Start (Actual): April 10, 2023
• Primary Completion (Actual): November 3, 2023
• Study Completion (Actual): November 3, 2023

Study Registration Dates

• First Submitted: March 29, 2023
• First Submitted That Met QC Criteria: March 29, 2023
• First Posted (Actual): April 11, 2023

Study Record Updates

• Last Update Posted (Actual): March 28, 2025
• Last Update Submitted That Met QC Criteria: March 7, 2025
• Last Verified: March 1, 2025

More Information

Terms related to this study

• Keywords: Mediterranean Diet; Low FODMAP Diet
• Additional Relevant MeSH Terms: Pathologic Processes; Intestinal Diseases; Disease; Digestive System Diseases; Gastrointestinal Diseases; Colonic Diseases; Colonic Diseases, Functional; Irritable Bowel Syndrome; Syndrome
• Other Study ID Numbers: HUM00227491; 5P30DK089503-13 (U.S. NIH Grant/Contract)

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