Effects of a Dietary Fiber on Fecal Microbiota and Metabolism

Study Overview
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Brief Summary
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The purpose of the study is to examine how a dietary fiber affects metabolism in healthy overweight and obese adults. The fiber will be added to foods that participants will consume for two, three-week periods. The fiber will be given in two doses -- 15 g per day during one period, and 30 g per day in the other. In another three-week period, they will consume the same foods, but with no fiber added. Major outcomes will include fermentability of the fiber, as assessed by measurement of breath hydrogen, as well as shifts in fecal bacteria. The caloric value of the fiber will be determined and metabolic measures related to blood glucose control and inflammation will also be taken.

Official Title
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Effects of a Dietary Fiber on Human Gut Microbiota, Bioactive Metabolites and Blood Glucose Control

Conditions
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Focus of the Study is on Gut Health

Intervention / Treatment
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* Dietary Supplement: Dietary Fiber


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Body mass index from 25 to 35 kg/m2. Willing to consume study foods and comply with dietary exclusions and specimen collection Exclusion Criteria: Pregnancy Diabetes Gastrointestinal disease Regular use of pre- or probiotics Recent use of antibiotics High intake of dietary fiber

Ages Eligible for Study
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Minimum Age: 20 Years
Maximum Age: 60 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: Prevention
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Low dose dietary fiber<br> | Dietary Supplement: Dietary Fiber<br>* Dietary fiber will be added to study foods<br>|
| Experimental: High dose dietary fiber<br> | Dietary Supplement: Dietary Fiber<br>* Dietary fiber will be added to study foods<br>|
| Placebo Comparator: No added fiber<br> | Dietary Supplement: Dietary Fiber<br>* Dietary fiber will be added to study foods<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Metabolizable energy | Urine and feces will be collected for 7 days at the end of each treatment period to allow for assessment of metabolizable energy | 7 days, 3 times | 
| Fermentability | Breath hydrogen will be measured hourly, over eight hours at the end of each treatment period | One, eight-hr day, three times | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Fecal microbiota | Fecal samples will be collected for 7 days at the end of each treatment period and for two days during washout periods | 2 days, three times, and 7 days, three times | 
| Blood glucose | An indwelling catheter will be placed and blood samples will be drawn over the course of an eight-hour period, at the end of each treatment period | For eight hours, three times |