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A Comparison of Three Different Treatment Options for Irritable Bowel Syndrome (CARIBS)

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details.
ClinicalTrials.gov Identifier: NCT02970591
Recruitment Status : Completed
First Posted : November 22, 2016
Last Update Posted : October 27, 2022
Information provided by (Responsible Party):
Magnus Simrén, Sahlgrenska University Hospital, Sweden

Brief Summary:
Irritable Bowel Syndrome is a common disease to which there is no curable treatment. Diet is considered to trigger symptoms associated with the clinical picture of IBS, and dietary treatment is thus believed to relieve the symptoms of IBS. As the disease is very heterogeneous in its manifestation, different treatment options might be indicated depending on the predominant symptom. To investigate the response to different dietary treatment options, a randomized controlled intervention trial will be carried out in adult patients (>18 y) with IBS according to Rome IV criteria. The aim of this study is to compare the response to two different dietary treatments or optimized medical treatment.

Condition or disease Intervention/treatment Phase
Irritable Bowel Syndrome Other: Traditional dietary advice and low FODMAP content Other: Low carbohydrate diet Other: Optimized Medical treatment Not Applicable

Detailed Description:

The study is a randomized controlled trial comparing three different treatments during four weeks:

  1. Combination of low FODMAP diet + traditional dietary advice (based on NICE recommendations)

    • Eat at regular hours; 3 main meals and 3 snacks
    • Eat in peace, chew the food properly
    • Peel all fruits and vegetables
    • Limit intake of spicy and fatty foods, coffe, alcohol, avoid fizzy drinks and chewing gum
    • Choose soluble rather than insoluble fibres
    • Avoid foods high in FODMAPs
  2. Diet low in carbohydrates

    • 10 E% carbohydrates, 23 E% protein, 67 E% fat
    • Larger amounts of fish, shellfish, meat, egg, dairy products (lactose free if wanted) nuts, seeds, oil, vegetables
    • No sugary or starchy foods, e.g pasta, potatoes, bread, rice, most fruits
    • No specific consideration about FODMAP content
  3. Optimized pharmacological tretament based on predominant symptom and previous experience with pharmacological treatmment.


  • Pain: Amitriptyline 25 mg. Increase to 50 mg if needed
  • Episodic pain: Hyoscyamine 0,2mg 2x2; adjust dose if needed
  • Pain with diarrhea: Amitriptyline 25 mg. Increase dose if needed
  • Pain with constipation: Linaclotide 290 microgram 1x1


  • Bulking agent (Sterculia gum (Inolaxol) 1x1. Increase to 1x3 if needed
  • Osmotic laxative (Macrogol (Movicol) 1x1
  • Linaclotide 290 microgram 1x1 Diarrhea
  • Loperamide 1x2 . Adjust dose if needed
  • Cholestyramine 1x1. Increase ever 3-5 d as needed
  • Ondansetron 4mg 1x1. Increase to 1x2-3 if needed
  • Eluxadoline 100mg 1x2

Primary endpoint: IBS-SSS reduction >50 points

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Study Type : Interventional  (Clinical Trial)
Estimated Enrollment : 300 participants
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single (Outcomes Assessor)
Primary Purpose: Supportive Care
Official Title: The Role of CARbohydrates in Irritable Bowel Syndrome (CARIBS): Protocol for a Randomized Controlled Trial Comparing Three Different Treatment Options
Study Start Date : January 2017
Actual Primary Completion Date : April 15, 2022
Actual Study Completion Date : April 29, 2022

Arm Intervention/treatment
Experimental: Diet A
Low carbohydrate diet
Other: Traditional dietary advice and low FODMAP content
Traditional dietary advice according to the Brittish Dietetic Association including reducing the intake of fermentable carbohydrates.

Active Comparator: Medical treatment
Optimized Medical treatment
Other: Optimized Medical treatment
Standard consultation by physician and if needed patients will receive medical treatment based on the most prominent symptom. Constipation: osmotic laxatives, linaclotide. Diarrhea: loperamid, bile acid binders. Pain: anti depressent, antispasmodics, linaclotide.

Experimental: Diet B
Traditional dietary advice and low FODMAP content
Other: Low carbohydrate diet
Diet that contains a maximum of 10 energy percent of carbohydrates, 23 energy % proteins and 67 energy % fat.

Primary Outcome Measures :
  1. The proportion (%) of patients who respond to treatment [ Time Frame: Baseline to 4 weeks ]
    A responder is defined as having an IBS-SSS reduction >50 points @ 4 weeks

Secondary Outcome Measures :
  1. Change in symptom severity [ Time Frame: Baseline, 4 weeks, 3 and 6 months ]
    Absolute and percentage change in IBS-SSS

  2. Determinants for GI symptoms by IBS-SSS [ Time Frame: Baseline, 4 weeks, 3 and 6 months ]
    GI symptoms measured by IBS-SSS

  3. Determinants for GI symptoms by GSRS-IBS [ Time Frame: Baseline, 4 weeks, 3 and 6 months ]
    GI symptoms measured by GSRS-IBS

  4. Predictors of response to treatment [ Time Frame: Baseline to 4 weeks ]
    Potential predictors include demographics, questionnaire data, microbiota, metabolites, immunology

  5. Adherence to allocated intervention [ Time Frame: Baseline, 4 weeks, 3 and 6 months ]
    Including compliance to dietary intervention during 4 weeks, and long-term adherence during follow-up

  6. Change in microbiota content [ Time Frame: Baseline, 4 weeks, 6 months ]
    Fecal microbiota analysis using 16S technique

  7. Change in extra-intestinal symptoms and quality of life [ Time Frame: Baseline, 4 weeks, 3 and 6 months ]
    As assessed by IBS specific questionnaires

  8. Change in metabolic profile [ Time Frame: Baseline, 4 weeks, 6 months ]
    Metabolomics in serum and urine samples

Other Outcome Measures:
  1. Qualitative assessment [ Time Frame: Approx. at 3 months follow-up ]
    Patient's subjective experiences related to the dietary intervention described by qualitative methods.

Information from the National Library of Medicine

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Ages Eligible for Study:   18 Years and older   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  • IBS according to ROME IV criteria, BMI 18-35, ability to communicate in Swedish, Gothenburg region resident

Exclusion Criteria:

  • Heart, liver, neurologic or psychiatric disease or illness
  • Serious gastrointestinal diseases
  • Celiac disease
  • Diabetes
  • Other conditions or surgery that affects the gastrointestinal function
  • Hyperlipidemia
  • Food allergy or intolerance other than lactose
  • Adherence to a specific diet
  • Being pregnant or breastfeeding
  • Previously been treated with any of the intervention arms, including having tested all of the pharmacological treatment options of relevance for the symptom profile of the patient

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT02970591

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Magnus Simren
Gothenburg, Non-US/Non-Canadian, Sweden, 44331
Sponsors and Collaborators
Sahlgrenska University Hospital, Sweden
Publications automatically indexed to this study by ClinicalTrials.gov Identifier (NCT Number):
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Responsible Party: Magnus Simrén, Professor, Sahlgrenska University Hospital, Sweden
ClinicalTrials.gov Identifier: NCT02970591    
Other Study ID Numbers: Car-IBS 1511-01
First Posted: November 22, 2016    Key Record Dates
Last Update Posted: October 27, 2022
Last Verified: October 2022
Individual Participant Data (IPD) Sharing Statement:
Plan to Share IPD: No
Keywords provided by Magnus Simrén, Sahlgrenska University Hospital, Sweden:
Additional relevant MeSH terms:
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Irritable Bowel Syndrome
Pathologic Processes
Colonic Diseases, Functional
Colonic Diseases
Intestinal Diseases
Gastrointestinal Diseases
Digestive System Diseases