Effects of Almond Consumption on the Human Gastrointestinal Microbiota and Metabolic Health

Study Overview
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Brief Summary
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The proposed work will investigate the effect of almond consumption as a snack on human gastrointestinal microbiota and on metabolic health.

Detailed Description
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This study is a randomized, controlled, investigator-blinded, parallel arm design with two treatment conditions. There will be a phone screening, in person pre-intervention testing, a one-week baseline period devoid of all nuts and seeds followed by a 12-week intervention period, and a post-testing appointment. Participants will be randomized to consume almonds or isocaloric snack for 12 weeks. Participants will provide stool samples during baseline testing and during the 12th week of the intervention.

Official Title
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SNACKing Study: Effects of Snacking on the Gastrointestinal Microbiota and Metabolism

Conditions
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Overweight and Obesity

Intervention / Treatment
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* Dietary Supplement: Almonds
* Dietary Supplement: Pretzels


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Males & Females 30-60 years of age BMI 25-34.9 kg/m^2 Ability to drop off fecal sample within 15 minutes of defecation Exclusion Criteria: Physician diagnosed metabolic or gastrointestinal diseases Fasting blood glucose >126 mg/dL Blood pressure >160/100 mm Hg Anemia Elevation in serum transaminases (i.e. >3 times the upper limit of normal) Evidence of liver disease, including primary biliary cirrhosis or gallbladder disease, constipation Currently taking lipid-lowering medications, oral hypoglycemic agents, or insulin, or medications known to impact bowel function. Pregnant, breastfeeding or postmenopausal Smoker, tobacco use Allergic to nuts Consume > 2 alcoholic beverages/day Abuse drugs Have had > 5% weight change in the past month or > 10% change in the past year Have taken antibiotics during the previous 2 months Unable to consume the experimental treatments (almonds or pretzels) Bariatric surgery Gallbladder removal Allergic to lidocaine or other topical anesthetics

Ages Eligible for Study
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Minimum Age: 30 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: Basic Science
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Intervention<br>The intervention arm consists of daily consumption of the investigator's intervention snack over the course of 12 weeks. | Dietary Supplement: Almonds<br>* Participants in the intervention group will consume 2oz of almonds daily over the course of 12 weeks.<br>|
| Placebo Comparator: Isocaloric Control<br>The control arm consists of daily consumption of an isocaloric snack over the course of 12 weeks. | Dietary Supplement: Pretzels<br>* Participants in the control group will consume an isocaloric amount of pretzels daily over the course of 12 weeks.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Changes in gastrointestinal microbiota composition | Determine the impact of daily consumption of almonds on the gastrointestinal microbiota compared to control (pretzels) by sequencing the V4 region of the 16S rRNA gene in fecal samples. | Baseline & 12-week mark | 
| Changes in abundance of fecal Roseburia spp | Determine the impact of daily consumption of almonds on the abundance of Roseburia spp. compared to control (pretzels) by using quantitative real-time PCR. | Baseline & 12-week mark | 
| Changes in abundance of fecal Butyryl CoA: Acetate CoA transferase | Determine the impact of daily consumption of almonds on the abundance of Butyryl CoA: Acetate CoA transferase gene compared to control (pretzels) by using quantitative real-time PCR. | Baseline & 12-week mark | 
| Changes in gastrointestinal microbial-derived metabolite concentrations | Determine the impact of daily consumption of almonds on the concentration of microbial-derived metabolites compared to control (pretzels) by using gas-liquid chromatography. These metabolites include butyrate and secondary bile acids. | Baseline & 12-week mark | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Changes in liver fat | Determine the impact of daily consumption of almonds on liver fat percentages compared to control (pretzels) by quantitative liver ultrasound. | Baseline & 12-week mark | 
| Changes in glycemic control. | Determine the impact on oral glucose tolerance within intervention (almond) and control (pretzel) groups by using a mixed meal tolerance test. | Baseline & 12-week mark | 
| Changes in secondary measures of gastrointestinal health. | Determine the impact of daily consumption of almonds on gastrointestinal health compared to control (pretzels) by measuring fecal pH; other microbial fermentation end products and microbial-derived bile acids using gas-liquid chromatography; and alpha- and beta- diversity measures of the gut microbiota community structure using 16S microbiota analyses. | Baseline & 12-week mark | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Almond, Gastrointestinal microbiota, Metabolic health, Bile acid profiles