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Completed

NCT Number: NCT07619573

EFFECT OF A DİETİTİAN-SUPERVİSED LOW-FODMAP DİET VERSUS STANDARD WRİTTEN ADVİCE ON GASTROİNTESTİNAL SYMPTOMS AND INFLAMMATORY BİOMARKERS İN IRRİTABLE BOWEL SYNDROME: A RANDOMİZED CONTROLLED TRİAL

Background:

Irritable Bowel Syndrome (IBS) is the most prevalent functional gastrointestinal (GI) pathology among GI disorders. Various dietary interventions, particularly the low-FODMAP diet, are employed to alleviate IBS symptoms.

Study Population & Design:

This study will include 78 adult patients, aged 18-65, diagnosed with IBS according to Rome IV criteria at the Biruni University Faculty of Medicine Hospital Gastroenterology Outpatient Clinic. Participants will be divided into two parallel groups:

Group 1 (n=39): Will receive dietary intervention solely through physician follow-up (provided with a standard hospital brochure listing prohibited foods).

Group 2 (n=39): Will receive structured, personalized dietary intervention through individualized nutritional counseling by a dietitian.

Duration: The low-FODMAP diet intervention for both groups will last for 8 weeks.

Outcome Measures:

At baseline (week 0) and at the conclusion of the study (week 8), the following assessments will be conducted:

Clinical Scores: IBS Symptom Severity Score (IBS-SSS) and the 15-item Gastrointestinal Symptom Rating Scale (GSRS).

Biomarkers: Hs-CRP and fecal calprotectin levels analyzed from blood and stool samples.

Objective:

The primary objective is to determine the impact of individualized nutritional counseling on GI symptoms and inflammatory biomarkers (hs-CRP, fecal calprotectin) during a low-FODMAP diet. Secondary objectives include evaluating the significance of the dietitian's role and observing how lifestyle factors (sleep and physical activity) influence symptom outcomes alongside nutritional therapy.

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Key information

Conditions

Irritable Bowel Syndrome (IBS) Colonic Diseases Colonic Diseases, Functional Digestive System Diseases Gastrointestinal Diseases Intestinal Diseases Irritable Bowel Syndrome

Age range

18 year–65 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Biruni University, Istanbul, Turkey (Türkiye)

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About this study

The low-FODMAP diet, developed for the treatment of IBS, is defined as a dietary regimen that restricts fermentable oligosaccharides, disaccharides, monosaccharides, and polyols-which are short-chain carbohydrates with limited or poor absorption.

Study Timeline and Interventions:

First Week: A 31-item "Data Collection Form" covering socio-demographic characteristics, health information, and nutritional habits will be administered.

Daily Monitoring: Daily records of the "Bristol Stool Scale" (BSS) will be maintained throughout the study.

Study Duration: The low-FODMAP diet intervention will be implemented for a total duration of 8 weeks.

Face-to-Face Assessments (Conducted at Baseline and Conclusion):

At the beginning and end of the study, the following assessments will be conducted face-to-face with the participants:

  • 24-hour Dietary Recall
  • Anthropometric measurements
  • Frequency of FODMAP-sourced food consumption over the past month
  • 7-item "International Physical Activity Questionnaire - Short Form" (IPAQ-SF)
  • 5-item "IBS Symptom Severity Score" (IBS-SSS)
  • 15-item "Gastrointestinal Symptom Rating Scale" (GSRS)
  • 8-item "Epworth Sleepiness Scale" (ESS)

Laboratory Analysis:

Hs-CRP and fecal calprotectin levels will be analyzed from blood and stool samples collected at baseline and at the conclusion of the study.

Who can participate

Healthy volunteers accepted: No

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

Inclusion criteria

  • Adults aged 18-65 years.
  • Diagnosed with IBS according to the Rome IV criteria.

Exclusion criteria

  • Use of antibiotics, NSAIDs, oral contraceptives, or hormone therapy during the study.
  • Pregnancy or breastfeeding.
  • Diagnosis of celiac disease

Treatment and study plan

Low-FODMAP Diet Intervention

Behavioral

This intervention consists of an 8-week low-FODMAP dietary regimen aimed at restricting the intake of short-chain carbohydrates, including fermentable oligosaccharides, disaccharides, monosaccharides, and polyols.

The intervention is administered through two distinct protocols to compare delivery methods: one group receives standard hospital care consisting of a brief physician follow-up accompanied by a standard educational brochure listing prohibited foods, while the other group receives structured, individualized nutritional counseling and personalized meal planning led by a professional dietitian.

Primary outcomes

  1. IBS-SSS

    Time frame: From enrollment to the end of treatment at 8 weeks

    Irritable Bowel Syndrome Symptom Severity Score (IBS-SSS). The IBS-SSS consists of 5 questions, each scored from 0 to 100, with a maximum possible total score of 500. It determines the severity of abdominal pain, abdominal pain frequency, abdominal bloating severity, satisfaction with bowel habits, and the impact of the disease on quality of life. Total scores are classified as follows: 75-174 points = mild IBS, 175-299 points = moderate IBS, and greater than or equal to 300 points = severe IBS. Higher scores indicate more severe IBS symptoms.

  2. GSRS

    Time frame: From enrollment to the end of treatment at 8 weeks

    Gastrointestinal Symptom Rating Scale (GSRS). The GSRS is a 15-item questionnaire that uses a 5-point Likert scale to assess the severity of gastrointestinal symptoms across 5 subscales: abdominal pain, reflux, diarrhoea, indigestion, and constipation. Scores are aggregated to determine symptom severity, where higher scores represent a higher severity of gastrointestinal symptoms.

  3. Fecal Calprotectin

    Time frame: From enrollment to the end of treatment at 8 weeks

    Fecal calprotectin levels will be analyzed from stool samples collected from participants to evaluate gastrointestinal inflammation.

  4. Hs-CRP

    Time frame: From enrollment to the end of treatment at 8 weeks

    High-Sensitivity C-Reactive Protein (hs-CRP). Hs-CRP levels will be analyzed from blood samples collected from individuals to monitor systemic biochemical findings of inflammation.

Secondary outcomes

  1. Anthropometric measurement data

    Time frame: From enrollment to the end of treatment at 8 weeks

    height in cm, body weight in kg, waist circumference in cm, hip circumference in cm, body composition and bioelectrical impedance analysis (BIA) measurements

  2. IPAQ-SF

    Time frame: From enrollment to the end of treatment at 8 weeks

    The IPAQ-SF is a seven-item measure that assesses individuals' physical activity levels over the past seven days. The scale inquires about walking, moderate and vigorous physical activities, and time spent sitting, and physical activity level is calculated in MET-minutes per week

  3. Epworth Sleepiness Scale (ESS)

    Time frame: From enrollment to the end of treatment at 8 weeks

    The ESS is an eight-item self-report measure that assesses an individual's likelihood of falling asleep in various everyday situations

  4. Data Collection Form

    Time frame: At the beginning of the study

    At the beginning of the study, a 31-item Data Collection Form; covering the sociodemographic characteristics, health information and dietary habits of participating patients was administered.

  5. Daily Total FODMAP Intake

    Time frame: From enrollment to the end of treatment at 8 weeks

    Food consumption records were taken for 3 days before and after the diet. The data was entered into the Bebis program. Food consumption records were calculated using the Nutrition Information System (BeBiS, version 9, Germany) for energy, macronutrients, micronutrients and FODMAP amounts (total FODMAP (g) = lactose (g) + oligosaccharides (g) + mannitol (g) + sorbitol (g)). Free fructose, a monosaccharide, could not be included in this programme as it could not be calculated.

Sponsors and collaborators

Lead sponsor

Biruni University

Other

Registry information

Important dates

Study start
2025
Primary completion
2025
Study completion
2025
First posted
Jun 2, 2026
Registry last updated
Jun 2, 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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