A Study to Evaluate the Influence of Diet on GI Health

Study Overview
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Brief Summary
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The purpose of this study is to understand the potential of protein and psyllium fiber to manipulate gut microbial densities, intestinal permeability, and inflammation in humans.

Official Title
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The Influence of Diet on Host Physiology and Disease Across Diverse Human Gut Microbiotas

Conditions
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Healthy

Intervention / Treatment
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* Other: High-fiber, low-protein diet
* Other: Low-fiber, high-protein diet


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Adults ≥ 18 years old On a baseline diet characterized by: Fiber intake of </= 20g/day, > 18% of daily calories from protein Exclusion Criteria: Prior history of gastrointestinal surgeries (except appendectomy and cholecystectomy) Known diagnosis of inflammatory bowel disease (Crohn's or ulcerative colitis), microscopic colitis, celiac disease, or other inflammatory GI condition Use of tobacco products within the past 6 months (since nicotine may affect intestinal permeability) Use of NSAIDs or aspirin and unable or unwilling to stop taking two weeks prior to permeability test and for the duration of the study Use of osmotic laxatives and unable or unwilling to stop taking one week prior to permeability test and for the duration of the study Use of oral corticosteroids and unable or unwilling to stop use of oral corticosteroids within the previous 6 weeks and for the duration of the study Multiple dietary restrictions or unable/unwilling to alter dietary protein or dietary fiber. Unwilling to stop ingestion of alcohol and artificial sweeteners such as Splenda™ (sucralose), Nutrasweet™ (aspartame), sorbitol, xylitol, lactulose, or mannitol 2 days before and during the permeability testing days, e.g. foods to be avoided are sugarless gums or mints and diet beverages Unwilling to stop stenuous exercise (running >5 miles or equivalent) one week prior to the permeability tests Bowel preparation for colonoscopy less than one week prior to completion of the first stool kit and permeability test and flexible sigmoidoscopy and upper endoscopy Pregnancy or plan to become pregnant during the study time frame Vulnerable adult Known bleeding disorders or takes medications that increase risk of bleeding from mucosal biopsies Use of oral antibiotic(s) within the past 4 weeks (can be enrolled after 4-week washout period) Use of commercial probiotic formulations and unwilling to stop for the duration of the study Diagnosis of diabetes Any other disease(s), condition(s) or habits(s) that would interfere with completion of study, or in the judgment of the investigator would potentially interfere with compliance to this study or would adversely affect study outcomes

Ages Eligible for Study
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Minimum Age: 18 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
Allocation: Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: Participants are randomly assigned to either the high-fiber, low protein diet or the low-fiber, high-protein diet.
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Other: High-fiber, low-protein diet<br>Participants will consume a high-fiber, low-protein diet for at least 4 weeks. All meals will be provided free of charge. No substitutions will be permitted. | Other: High-fiber, low-protein diet<br>* Diet will consist of at least 15g fiber above baseline and less than 10% of calories from protein.<br>|
| Other: Low-fiber, high-protein diet<br>Participants will consume a low-fiber, high-protein diet for at least 4 weeks. All meals will be provided free of charge. No substitutions will be permitted. | Other: Low-fiber, high-protein diet<br>* Diet will consist of less than 15g fiber and greater than 18% of calories from protein<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Urinary Excretion of Lactulose and 13C-Mannitol | Small Bowel and Colonic Permeability by Urinary Excretion of Lactulose and 13C-Mannitol after Oral Ingestion of lactulose and 13C mannitol (5:1 ratio by mass). The 0-2h urine most closely reflects small intestinal permeability and 8-24h urine reflects colonic permeability. HPLC-tandem mass spectrometry will be used for detection of the sugars. The results will be expressed as the ratio of percentage excretion of the ingested dose of lactulose and mannitol in urine. | 4 weeks | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in gut microbial alpha diversity based on Shannon index | Stool samples will be processed to extract DNA, followed by metagenomic sequencing and assessment of alpha diversity using Shannon index. Comparison will be made using ttest. | 4 weeks | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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High-Protein, Low-Fiber Diet