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

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

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

Study Overview

• Status: Completed
• Conditions: Overweight and Obesity
• Intervention / Treatment: Dietary supplement: Almonds; Dietary supplement: Pretzels

Detailed Description

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.

• Study Type: Interventional
• Enrollment (Actual): 40
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Illinois
    • Urbana, Illinois, United States, 61801
      • University of Illinois at Urbana-Champaign

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 30 years to 60 years (Adult)
• Accepts Healthy Volunteers: Yes

Description

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

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

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

What is the study measuring?

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

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Changes in markers of systemic inflammation & metabolism	Determine the impact of daily consumption of almonds on inflammation and metabolism compared to control (pretzels) by measuring biomarker concentrations with ELISA. Specifically, we will look at TNF, CRP, & LPS-BP (inflammatory) and NEFAs (metabolism).	Baseline & 12-week mark
Changes in adiposity.	Determine the impact of daily consumption of almonds on adiposity compared to control (pretzels) using a DXA scan.	Baseline & 12-week mark
Changes in subjective measures of gastrointestinal health.	Determine the impact of daily consumption of almonds on subjective measures of gut health compared to control (pretzels) using stool records. The questionnaire addresses questions related to gastrointestinal health including bloating, flatulence, and stool consistency.	Baseline & 12-week mark

Collaborators and Investigators

• Sponsor: University of Illinois at Urbana-Champaign
• Collaborators: Almond Board of California
• Investigators: Principal Investigator: Hannah D Holscher, PhD RD, University of Illinois at Urbana-Champaign

Study record dates

Study Major Dates

• Study Start (Actual): February 10, 2020
• Primary Completion (Actual): December 20, 2023
• Study Completion (Actual): December 20, 2023

Study Registration Dates

• First Submitted: November 12, 2019
• First Submitted That Met QC Criteria: January 7, 2020
• First Posted (Actual): January 10, 2020

Study Record Updates

• Last Update Posted (Actual): December 6, 2024
• Last Update Submitted That Met QC Criteria: December 3, 2024
• Last Verified: December 1, 2024

More Information

Terms related to this study

• Keywords: Metabolic health; Gastrointestinal microbiota; Almond; Bile acid profiles
• Additional Relevant MeSH Terms: Nutrition Disorders; Overnutrition; Body Weight; Overweight
• Other Study ID Numbers: 20154

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No