The Low FODMAP Diet in Individuals With Small Intestinal Bacterial Overgrowth (SIBO)

NCT07424313 | Completed

• 1 other identifier: 11/RKE/2023/U
• Study Type: interventional
• Target: 51
• Locations: 1 country
• Sites: 1

Brief Summary

This study aims to assess the impact of a low FODMAP diet (LFD) on gastrointestinal symptoms and nutritional status in individuals diagnosed with small intestinal bacterial overgrowth (SIBO). Participants were randomly assigned to either an intervention group or a control group following completion of antibiotic therapy. The intervention group followed a LFD, while the control group followed a normal diet, in accordance with the principles of rational nutrition. Gastrointestinal symptoms, nutritional status, and quality of life were assessed using questionnaires, dietary records, anthropometric measurements, and blood biochemical parameters.

Conditions

SIBO; Small Intestinal Bacterial Overgrowth; Small Intestinal Bacterial Overgrowth Syndrome (SIBO)

Outcome Measures

Primary Outcomes (9)

• Gastrointestinal Adverse Symptoms Assessment Questionnaire (GASAQ) total score

  Change in gastrointestinal symptom severity assessed using the Gastrointestinal Adverse Symptoms Assessment Questionnaire (GASAQ). The total score ranges from 0 to 100 points, with higher scores indicating more severe gastrointestinal symptoms. Assessments were performed at baseline and after the dietary intervention.

  12 weeks

• Nutritional status - Mini Nutritional Assessment (MNA)

  Change in nutritional status assessed using the Mini Nutritional Assessment (MNA) questionnaire. The total score ranges from 0 to 30 points, with higher scores indicating better nutritional status. Assessments were performed at baseline and after the dietary intervention.

  12 weeks

• Nutritional status - Blood biochemical parameters (Serum vitamin D concentration)

  Change in serum vitamin D levels measured in ng/mL at baseline and after the dietary intervention.

  12 weeks

• Nutritional status - Blood biochemical parameters (Serum folate concentration)

  Change in serum folate levels measured in ng/mL at baseline and after the dietary intervention.

  12 weeks

• Nutritional status - Blood biochemical parameters (Iron status parameters)

  Change in serum iron concentration (µg/dL) measured at baseline and after the dietary intervention.

  12 weeks

• Nutritional status - Blood biochemical parameters (Serum albumin concentration)

  Change in serum albumin levels measured in g/L at baseline and after the dietary intervention.

  12 weeks

• Nutritional status - Anthropometric parameters (body weight)

  Change in body weight (kg) measurements at baseline and after the dietary intervention.

  12 weeks

• Nutritional status - Anthropometric parameters (body mass index (BMI)

  Change in BMI (kg/m²) at baseline and after the dietary intervention. BMI calculated from measured body weight and height (kg/m²).

  12 weeks

• Nutritional status - anthropometric parameters (body fat percentage)

  Change in body fat percentage (%) at baseline and after the dietary intervention. Body fat percentage measured using bioelectrical impedance analysis (ACCUNIQ BC720).

  12 weeks

Secondary Outcomes (2)

• Quality of life - IBS-specific (Irritable Bowel Syndrome-Quality of Life (IBS-QOL) total score)

  12 weeks

• Quality of Life - General (Short Form-36 Health Survey (SF-36) total score)

  12 weeks

Study Arms (2)

Low FODMAP Diet Intervention Group

EXPERIMENTAL

Participants diagnosed with SIBO who followed a low FODMAP diet after completion of antibiotic therapy.

Other: Low FODMAP Diet

Control Group

SHAM COMPARATOR

Participants diagnosed with SIBO who followed a diet consistent with the principles of healthy eating after completion of antibiotic therapy.

Other: Healthy Eating Diet

Interventions

Low FODMAP Diet OTHER

Following a low FODMAP diet (elimination and reintroduction phases for 4 and 8 weeks, respectively, for a total of 12 weeks)

Low FODMAP Diet Intervention Group

Healthy Eating Diet OTHER

Applying recommendations consistent with proper nutrition principles, with particular focus on breaks between meals and the principle of mindful eating

Control Group

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• age \> 18 years,
• SIBO diagnosed by a doctor based on a hydrogen and methane breath test,
• the use of one type of antibiotic at the same dose and for the same period of time.

You may not qualify if:

• BMI \< 18.5 kg/m2,
• pregnancy and breastfeeding,
• the occurrence of allergies and food intolerances,
• previous operations on the digestive tract (except appendectomy and hemorrhoidectomy),
• eating disorders,
• inflammatory bowel diseases,
• celiac disease,
• cancer, heart, liver and lung diseases with severe course, as well as neurological or psychiatric diseases,
• use of dietary modifications in the last 3 months,
• use of antibiotics other than those prescribed by a doctor to treat SIBO in the last 3 months,
• implanted stimulators (limitation of body composition measurement)

Sponsors & Collaborators

• Warsaw University of Life Sciences: lead

Study Sites (1)

Warsaw University of Life Sciences (WULS-SGGW)

Warsaw, 02-776, Poland

Location

MeSH Terms

Interventions

FODMAP Diet; Diet, Healthy

Intervention Hierarchy (Ancestors)

Elimination Diets; Diet; Nutritional Physiological Phenomena; Diet, Food, and Nutrition; Physiological Phenomena

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: PARTICIPANT
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: university professor

Study Record Dates

• First Submitted: February 8, 2026
• First Posted: February 20, 2026
• Study Start: February 8, 2024
• Primary Completion: September 18, 2025
• Study Completion: January 15, 2026
• Last Updated: February 24, 2026

Record last verified: 2026-02

Data Sharing

• IPD Sharing: Will not share

Locations

PL (1)