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Completed

NCT Number: NCT04830410

The Effects of Carbohydrates in Irritable Bowel Syndrome

Food and their components are often reported as gastrointestinal (GI) symptom triggers in patients with IBS. The current interest in dietary management in IBS, has largely focused on the negative effect of poorly absorbed and subsequently fermented carbohydrates (FODMAP - Fermentable Oligo-, Di-, Mono-saccharides And Polyols). These unabsorbed carbohydrates can generate GI symptoms through osmosis, with increased amount of fluid in the gut lumen, and via modification of gut microbiota composition and function (fermentation and production of gas).

Studies assessing diets low in FODMAPs have shown promising results in symptom improvement in some IBS patients, but not in all. The low FODMAP diet, as it is used today, is restrictive and difficult for patients to accommodate in their daily life. Moreover, the effect of this diet on microbiota composition and function is not defined, and there are also concerns that restrictive diets may lead to nutritional inadequacy.

Fructan is a specific FODMAP which is built of fructose polymers. Examples of foods that contain fructans are wheat, onion, garlic and banana. The daily dietary intake of fructans varies approximately between 3 and 6 grams. Fructans are potential triggers of GI symptoms in IBS however, they are currently also used as prebiotic supplements. A recent systematic review and meta-analysis concluded that low dosages of fructans do not worsen GI symptoms, but they do increase the beneficial bifidobacteria. It remains unclear whether the potential benefits of fructans outweigh the potential harmful effects in patients with IBS.

The investigators are aiming to assess the effects of fructans, as well as predictive factors and mechanisms involved, and to compare with placebo in IBS patients. The investigators will assess GI symptom severity, visceral sensitivity, intestinal gas production, gut immunity and microbiota, and metabolites produced in the gut.

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Key information

Conditions

Irritable Bowel Syndrome With Diarrhea

Age range

18 year–50 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Sahlgrenska University Hospital

Gothenburg, Sweden

Who can participate

Healthy volunteers accepted: No

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

Inclusion criteria

  • IBS according to ROME IV criteria (with diarrhoea)

Exclusion criteria

  • Celiac disease or any other gastroenterology disease (such as inflammatory bowel disease, celiac disease, microscopic colitis, diverticulitis, radiation enteritis).
  • Suspected or known strictures, fistulas or physiological/mechanical GI obstruction, history of gastric bezoar.
  • Appendicectomy and cholecystectomy <3 months.
  • Heart-, liver-, neurological-, or current psychiatric disease, diabetes, obesity (BMI>30), other disease or surgery to the abdomen that affected intestinal function.
  • Implantable or portable electro-mechanical medical devices, e.g. pacemakers.
  • Swallowing disorders/dysphagia to food or pills.
  • Allergy or intolerances to foods.
  • Compliance to a special diet (including vegan, vegetarian, gluten-free or low FODMAP diet).
  • Pregnant or breast feeding.
  • Usage of antibiotics within 4 weeks prior to inclusion
  • Usage of alcohol more than 14 units per week.
  • No new pharmacological treatment during the study period.
  • Medications: laxatives, neuromodulators or opioids (morphine, codeine, tramadol…)

Treatment and study plan

Fructan reintroduction

Dietary Supplement

Patients will reintroduce fructan powder after 14-day of a low FODMAP diet

Placebo reintroduction

Dietary Supplement

Patients will reintroduce placebo powder after 14-day of a low FODMAP diet

Primary outcomes

  1. IBS-SSS

    Time frame: before and after the reintroduction (7days +/-3 days)

    change in irritable bowel syndrome severity scoring system (IBS-SSS) between the 2 groups. IBS-SSS is between 0 and 500, with a higher score meaning more severe symptoms.

Secondary outcomes

  1. visceral sensitivity

    Time frame: Baseline

    measured by a rectal barostat, predictor for a better GI response to a low FODMAP diet and predictor of a worse GI response to fructan reintroduction

  2. change in intestinal gas production

    Time frame: between baseline and after (7days +/-3 days) of reintroduction

    measured by a gas sensing capsule (Atmo), between the 2 groups

  3. change in gas production

    Time frame: between baseline and after (7days +/-3 days) of reintroduction

    measured by breath tests (H2 and CH4) between the 2 groups.

  4. change in microbiota

    Time frame: between baseline, after the low FODMAP diet (14 days) and after reintroduction (7+/-3 days)

    Fecal microbiota analysis using 16S technique between the 2 groups.

  5. Change in metabolomics profiles

    Time frame: between baseline, after the low FODMAP diet (14 days) and after reintroduction (7+/-3 days)

    Targeted and untargeted metabolomics in urine, blood and stool samples measured by Liquid and gas chromatography-mass spectrometry between the 2 groups.

  6. change in stool form and frequency

    Time frame: between baseline, after the low FODMAP diet (14 days) and after reintroduction (7+/-3 days)

    Stool diary between the 2 groups.

  7. GSRS-IBS

    Time frame: between baseline, after the low FODMAP diet (14 days) and after reintroduction (7+/-3 days)

    change in Gastrointestinal symptom rating scale-IBS (GSRS-IBS) between the 2 groups. GSRS-IBS assesses five GI symptom domains: satiety, abdominal pain, diarrhea, constipation and bloating. The five domains are calculated using the mean of two to four items scored with 7-point Likert scales, with higher scores representing more severe symptoms.

  8. HAD

    Time frame: between baseline, after the low FODMAP diet (14 days) and after reintroduction (7+/-3 days)

    change in Hospital Anxiety and depression scale (HAD) between the 2 groups. HAD assesses the severity of psychological distress, i.e. anxiety and depression. In this 14-item scale, seven items measure anxiety and the other seven measure depression on a 4-point Likert scale (0-3) which provides a score between 0 (absence) and 21 (high level). Scores higher than 10 on each of the subscales is considered to define clinically relevant anxiety and/or depression.

  9. VSI

    Time frame: between baseline, after the low FODMAP diet (14 days) and after reintroduction (7+/-3 days)

    change in Visceral sensitivity index (VSI) between the 2 groups. VSI is a 15-item validated scale measuring GI symptom-specific anxiety, i.e. the cognitive, affective, and behavioural response to fear of GI sensations, symptoms, and the context in which these occur. The total score ranges between 0 (no GI-specific anxiety) to 75 (severe GI-specific anxiety).

  10. IBSQOL

    Time frame: between baseline, after the low FODMAP diet (14 days) and after reintroduction (7+/-3 days)

    change in irritable bowel syndrome quality of life (IBSQOL) questionnaire between the 2 groups. IBSQOL is a disease-specific, self-administered questionnaire, with 30 items measuring nine aspects of health-related quality of life during the past four weeks. The nine domains are emotional health, mental health, sleep, energy, physical functioning, food/diet, social role, physical role and sexual relations. Each question has five or six response options. For each subscale, the score is transformed to a 0-100 scale. A higher score represents a better quality of life.

  11. PHQ12

    Time frame: between baseline, after the low FODMAP diet (14 days) and after reintroduction (7+/-3 days)

    change in patient health questionnaire 12 (PHQ12) between the 2 groups. The PHQ-15 is a somatic symptom subscale derived from the full PHQ. It inquires about 15 somatic symptoms; each individual symptom is coded as 0, 1, or 2, and the total score ranges from 0 to 30, with higher scores representing more severe symptoms.

  12. CSI

    Time frame: between baseline, after the low FODMAP diet (14 days) and after reintroduction (7+/-3 days)

    change in Central Sensitization Inventory (CSI) between the 2 groups. The responses were graded on a Likert scale from 0 (never) to 4 (always). The total score ranges from 0 to 100. A higher score suggest higher central sensitization syndrome.

  13. IBS-SSS

    Time frame: between baseline, after the low FODMAP diet (14 days) and after reintroduction (7+/-3 days)

    change in irritable bowel syndrome severity scoring system (IBS-SSS) between the 2 groups.

Sponsors and collaborators

Lead sponsor

Sahlgrenska University Hospital

Other

Collaborators

  • Atmo Biosciences Pty Ltd
  • Beneo-Institute

Registry information

Official study title

The Effects of Fructans in Irritable Bowel Syndrome

Acronym: FIBS

Important dates

Study start
2021
Primary completion
2025
Study completion
2025
First posted
Apr 5, 2021
Registry last updated
Nov 24, 2025

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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