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Completed

NCT Number: NCT07424313

The Low FODMAP Diet in Individuals 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.

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Key information

Conditions

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

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Warsaw University of Life Sciences (WULS-SGGW)

Warsaw, 02-776, Poland

Who can participate

Healthy volunteers accepted: No

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

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)

Treatment and study plan

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)

Healthy Eating Diet

Other

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

Primary outcomes

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Nutritional status - Anthropometric parameters (body weight)

    Time frame: 12 weeks

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

  8. 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).

  9. 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).

Secondary outcomes

  1. 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.

  2. 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.

Sponsors and collaborators

Lead sponsor

Warsaw University of Life Sciences

Other

Registry information

Official study title

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

Important dates

Study start
2024
Primary completion
2025
Study completion
2026
First posted
Feb 20, 2026
Registry last updated
Feb 24, 2026

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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