Low Carbohydrate Small Intestine Study

Study Overview
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Brief Summary
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The investigators will recruit probands with a ileo- or colostoma that are otherwise in good general health and analyse the stomal fluids for their microbiota composition. Sampling will be performed over a time span of 28 days, after 14 days probands will modify their base-line diet to a low carbohydrate diet.

Detailed Description
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Additionally to stoma fluids which will be analyzed for their microbiota composition the investigators will also collect skin samples to analyze for microbiota composition and urine to analyze for metabolite composition. Low carbohydrate diet will allow for consumption of 80g complex carbohydrates per day, simple sugars will have to be avoided completely

Official Title
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Studying the Impact of a Low Carbohydrate Diet on the Small Intestinal Microbiota

Conditions
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Diet, Healthy

Intervention / Treatment
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* Other: Diet modification


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Ileostomy or colostomy Good general health Written informed consent Exclusion Criteria: Major metabolic diseases that prevent adherence to low carbohydrate diet Participation in other clinical trial interfering with study protocol

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Intervention Model: Sequential Assignment
Interventional Model Description: First phase will be purely observational, second phase involves diet modification
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: All study participants<br>All participants will undergo sample collection during their regular diet and after modification of their diet to a low carbohydrate diet | Other: Diet modification<br>* Participants will reduce their carbohydrate consumption to 80g daily<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Assessment of microbiota profile by 16S sequencing before and after diet modification for significant differences | Sample content will be measured by 16S sequencing, ecological distances will be assessed by beta-diversity | 28 days | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Relative changes of total metabolite abundance in urine | The whole metabolite composition will be assessed by an untargeted screen done with mass spectrometry | 28 days | 
| Analysis of microbiota metabolic potential (microbiome DNA coding for enzymes) after shotgun sequencing | The total DNA content of the samples will be annotated for for known metabolic active enzymes to assess functionality | 28 days | 
| Analysis of microbiota biomass | The samples will be analysed for the number of bacteria present in them | 28 days | 
| Changes of further metagenomic microbiome composition (viral, eucaryotic DNA) | The DNA of the samples will be screened for parts belonging to viruses or eucaryotic cells | 28 days | 
| Culturing of microbiota if appropriate (in vitro) | If of interest, culturing of specific bacterial strains will be attempted in vitro with the aim to recreate in vivo observations | 28 days |