Effects of a Very Low Carbohydrate Diet on Symptoms of Irritable Bowel Syndrome (IBS)

Study Overview
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Brief Summary
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The purposes of this study are to prospectively determine the effect of a very low carbohydrate diet on quality of life and gastrointestinal symptoms in patients with diarrhea-predominant irritable bowel syndrome (IBS-D); and to determine possible physiological correlates of symptom improvement, as related to post-prandial 5-hydroxytryptamine (5-HT) release, weight loss and fiber content.

Detailed Description
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Approximately 10-15% of individuals in the United States have symptoms consistent with irritable bowel syndrome (IBS) which is a costly disorder and negatively impacts patient quality of life. The pathogenesis of this heterogeneous disorder is still not well understood. Patients frequently identify worsening of symptoms after meals and often cite particular foods as triggers of their IBS symptoms. Unfortunately, there is insufficient randomized clinical trial data to allow for specific dietary recommendations. Previous research has suggested a role for carbohydrate ingestion in IBS. There is also evidence for the role of the post-prandial release of 5-hydroxytryptamine (5-HT) and its turnover (as represented by the ratio of its metabolite, 5-hydroxyindoleacetic acid (5-HIAA), to 5-HT in response to a carbohydrate-rich meal, especially in those with IBS-D. As the prevalence of overweight (body mass index [BMI] > 25 kg/m2) and obesity (BMI > 30 kg/m2) has risen in recent years, very low carbohydrate diets have become popular for those attempting to lose weight. Patients with IBS, especially IBS-D, anecdotally report improvement in their gastrointestinal symptoms after initiating a very low carbohydrate diet. However, no study has investigated the effect of a very low carbohydrate diet on symptoms and quality of life in patients with IBS-D.

Official Title
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The Effect of a Very Low Carbohydrate Diet on Symptoms of Irritable Bowel Syndrome: A Prospective Pilot Study

Conditions
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Diarrhea Predominant Irritable Bowel Syndrome

Intervention / Treatment
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* Other: Very low carbohydrate diet


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Age 18-70 years old, male or female Meet Rome II Criteria for IBS-D Body mass index > 25 kg/m^2 Desire to use a very low carbohydrate diet for weight loss Score of > 36 on the FBDSI Ability to understand consent form In stable health by screening history, physical examination performed by a study physician, laboratory tests (normal blood counts, kidney function tests, liver tests, TSH). Exclusion Criteria: Age < 18 years or age > 70 years History of inflammatory bowel disease History of any gastrointestinal surgery that preceded the onset of IBS symptoms Pregnancy or breastfeeding FBDSI symptom score of ≤ 36 Inability to understand consent form Diabetes requiring medications (must be controlled with diet and exercise alone). Chronic narcotic use for any reason Use of serotonin-selective reuptake inhibitors unless patient has been on a stable dose for at least 4 weeks. Use of any over-the-counter or prescription weight loss medications. Any chronic or unstable diseases (e.g., kidney disease, heart disease, or cancer) that may put the subject at increased risk from the intervention Any of the following baseline abnormalities of laboratory tests or physical exam findings: Serum creatinine > 1.5 mg/dL in men, > 1.3 mg/dL in women. Liver disease (AST or ALT > 2 times the upper limit of normal or total bilirubin > 1.6mg/dL). Blood pressure > 160/100 mm Hg. Fasting triglycerides > 600 mg/dL. Fasting serum low-density lipoprotein (LDL) cholesterol > 190 mg/dL.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 70 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: A<br> | Other: Very low carbohydrate diet<br>* 4 weeks on strictly controlled low carbohydrate diet<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Number of Subjects Reporting Adequate Relief From IBS Symptoms for the Previous Week. Adequate Relief Was a True/False Item. | Adequate relief was measured as the primary endpoint via a single item Adequate Relief Question asking Over the past week have you had adequate relief of your symptom experience. Higher scores represent greater levels of adequate relief over the week prior to the assessment. Participants completed this 1-item questionnaire at the end of each of weeks of the study, assessing whether they had adequate relief of their IBS symptoms for the week. A responder was defined as reporting adequate relief in at least 2 of the 4 weeks on the VLCD. | At the end of each of 6 study weeks | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Impact of Very Low Carbohydrate Diet on Stool Frequency | Stool Frequency was measured as number of stools per day | 6 Weeks | 
| Sickness Impact Profile | Units of measurement on the Sickness Impact Profile were ordinal rated scored. Information on scoring use and interpretation of the Sickness Impact Profile, readers are encouraged to read Bergner et. al. 1981 - Bergner, M., Bobbit, R.A., Carter, W.B. et all (1981) the Sickness Impact Profile: Development and final revision of a health status measure. Medical Care, 19:787-805 The SIP measures sickness-related dysfunction based on behavior in order to provide a measure of health status that will aid in assessing the outcome of health care services. | At the end of four week VLCD | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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D-IBS (diarrhea predominant irritable bowel syndrome)