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

February 20, 2026 updated by: dr hab. Ewa Lange, prof. SGGW, Warsaw University of Life Sciences

Assessment of the Impact of the Low FODMAP Diet on Gastrointestinal Symptoms and Nutritional Status in People With Small Intestinal Bacterial Overgrowth (SIBO)

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.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
51

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Poland
      • Warsaw, Poland, 02-776
        • Warsaw University of Life Sciences (WULS-SGGW)

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • 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.

Exclusion Criteria:

  • 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)

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

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

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Low FODMAP Diet Intervention Group
Participants diagnosed with SIBO who followed a low FODMAP diet after completion of antibiotic therapy.
Other: Low FODMAP Diet
Following a low FODMAP diet (elimination and reintroduction phases for 4 and 8 weeks, respectively, for a total of 12 weeks)
Sham Comparator: Control Group
Participants diagnosed with SIBO who followed a diet consistent with the principles of healthy eating after completion of antibiotic therapy.
Other: Healthy Eating Diet
Applying recommendations consistent with proper nutrition principles, with particular focus on breaks between meals and the principle of mindful eating

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Gastrointestinal Adverse Symptoms Assessment Questionnaire (GASAQ) total score
Time Frame: 12 weeks
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)
Time Frame: 12 weeks
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)
Time Frame: 12 weeks
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)
Time Frame: 12 weeks
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)
Time Frame: 12 weeks
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)
Time Frame: 12 weeks
Change in serum albumin levels measured in g/L at baseline and after the dietary intervention.
12 weeks
Nutritional status - Anthropometric parameters (body weight)
Time Frame: 12 weeks
Change in body weight (kg) measurements at baseline and after the dietary intervention.
12 weeks
Nutritional status - Anthropometric parameters (body mass index (BMI)
Time Frame: 12 weeks
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)
Time Frame: 12 weeks
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 Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Quality of life - IBS-specific (Irritable Bowel Syndrome-Quality of Life (IBS-QOL) total score)
Time Frame: 12 weeks
Change in quality of life assessed using the Irritable Bowel Syndrome-Quality of Life (IBS-QOL) questionnaire. Scores range from 0 to 100 points, with higher scores indicating better quality of life. Assessments were performed at baseline and after the dietary intervention.
12 weeks
Quality of Life - General (Short Form-36 Health Survey (SF-36) total score)
Time Frame: 12 weeks
Change in general quality of life assessed using the Short Form-36 Health Survey (SF-36), Polish version. Scores range from 0 to 100 points, with higher scores indicating better perceived health status. Assessments were performed at baseline and after the dietary intervention.
12 weeks

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Warsaw University of Life Sciences

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
February 8, 2024

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
September 18, 2025

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
January 15, 2026

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
February 8, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
February 13, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
February 20, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
February 24, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
February 20, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
February 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • 11/RKE/2023/U

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

The study will not share individual participant data to protect participant confidentiality and privacy.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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