Food Effects on the Gut Microbiota

Study Overview
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Brief Summary
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This is a small-scale study of the effects on microbes in the human gut of adding high-fiber snack foods to usual diet. The snack foods are being provided by Mondelez International, Inc. Eight pairs of dizygotic twins, discordant or concordant for obesity, will participate in the study. They will complete 3 successive experiments in which their regular diet is supplemented by consumption, over a 6-week period, of high-fiber snack foods. Each experiment will involve (i) two weeks consuming regular diet (fecal sample collected weekly); (ii) one week consuming one snack food per day (approximately 7 g fiber, collection of all fecal samples), (iii) one week consuming two snack foods per day (approximately 14 g fiber, collection of all fecal samples), (iv) four weeks consuming three snack foods per day (approximately 20 g fiber, collection of all fecal samples); and (v) two weeks consuming only regular diet (weekly collection of fecal sample). For each experiment, participants will also provide a fasting blood sample during the free diet phase at the end of the week just before initiation of snack consumption, and a fasting blood sample at the end of the last week of snack consumption. Participants will also collect one first morning urine sample weekly throughout the study. During week 2, participants will also collect first morning urine samples for 3 consecutive days. Similarly, they will collect first morning urine samples for the last 3 consecutive days of the last week of snack consumption. The study will test the effects of the different fiber-rich snacks on the composition and metabolic properties of the gut microbial community in lean and obese subjects.

Official Title
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Effects of High-fiber Snack Foods on Human Gut Microbes

Conditions
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Gut Microbial Responses to Dietary Fiber

Intervention / Treatment
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* Other: high-fiber food type


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: * member of female dizygotic twin pair discordant or concordant for obesity Exclusion Criteria: pregnant or trying to get pregnant inflammatory bowel disease gastrointestinal cancer hepatitis HIV renal failure food allergies

Ages Eligible for Study
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Minimum Age: 31 Years
Maximum Age: 45 Years

Sexes Eligible for Study
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Female

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: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Participants<br>Consumption of a given type of high-fiber snack food, with each individual functioning as her own control | Other: high-fiber food type<br>* In 3 successive experiments, usual diet will be supplemented with snack foods containing fiber of plant, fruit or grain origin.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Assessment of gut microbial community structure and function | Sequencing bacterial 16S rRNA amplicons plus shotgun sequencing of fecal community DNA to identify effects of fiber-enriched foods on bacterial community and gene representation; mass spectrometry of products of gut microbial community metabolism. | 8 weeks |