Gut Microbial Metabolites of Apple Polyphenols (GutMMAP)

Gut Microbial Metabolites Of Apple Polyphenols: Interrogating Individual Differences To Establish Functional Biomarker Utility

The goal of this controlled feeding trial is to learn about the metabolism of polyphenols, a common class of compounds found in plant-based foods, by the gut microbiome. It will evaluate how differences in gut bacteria across individuals influence metabolism of polyphenols from foods, which may influence health benefits that people receive from different foods.

Study Overview

• Status: Completed
• Conditions: Healthy; Controlled Feeding Trial
• Intervention / Treatment: Other: Dietary intervention - apple catechin diet; Other: Dietary intervention - low catechin diet

Detailed Description

This is a randomized, cross-over controlled feeding trial. Thirty healthy adult volunteers will be selected to participate on the basis of urinary screening results measuring a gut bacterial metabolite that is produced following consumption of a soy food: 15 O-desmethylangolensin (ODMA) producers and 15 age and gender-matched ODMA non-producers will be included. Participants will be assigned to consume two diets in random order: an apple catechin diet that provides a controlled amount of catechins in apple juice, and a nutritionally-matched low catechin diet. Both diet phases will last 3 days, with a 10 day washout period in between the two diet phases.

• Study Type: Interventional
• Enrollment (Actual): 32
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Maryland
    • College Park, Maryland, United States, 20742
      • Department of Nutrition and Food Science

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

1. Completion of informed consent.
2. Stated willingness to comply with all study procedures and availability for the duration of the study.
3. Any gender identification, aged 18 - 45.
4. BMI 18.5 - 40 kg/m^2
5. Ability to consume the intervention foods and beverages and be willing to adhere to the dietary regimen.
6. Agreement to provide urine and fecal samples according to the study protocol.
7. Agreement to adhere to avoid high catechin foods (tea, chocolate) for 4 weeks.
8. Able to come to the study location for 8 visits according to the study schedule.
9. As assessed through an initial urine screening phase, a person is eligible either on the basis of (1) the presence of a urinary marker for soy isoflavone metabolism (ODMA), or (2) as a control matched for age and gender.

Exclusion Criteria:

1. Current, regular use of antacids or acid reducers.
2. Systemic antibiotic use within the past month prior to the urinary screening until completion of the dietary intervention.
3. Pregnancy or lactation, within 3 months post-partum (regardless of breastfeeding) at screening or planning to become pregnant during the study duration.
4. Known allergic reactions to components of the foods or beverages of the study diet (soy, wheat, dairy, peanut, tree nuts, apples, eggs) or any history of anaphylactic food allergy.
5. Current diagnosis of renal, hepatic, or gastrointestinal conditions.
6. History of stroke.
7. Underweight (BMI <18.5 kg/m^2) or severe obesity (BMI >40 kg/m^2).
8. Under 18 years or above 45 years of age.
9. Unwilling or unable to participate in the controlled dietary intervention or provide urine or fecal samples.
10. Has a pacemaker, implanted defibrillator, or other implanted electronic device.
11. Change of body weight >10% between screening and dietary intervention.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Triple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Apple catechin; A 3-day controlled diet	Other: Dietary intervention - apple catechin diet; The intervention will provide a catechin-containing apple juice, for consumption alongside a low catechin diet tailored to participants calorie needs for weight maintenance.
Placebo Comparator: Low catechin; A 3-day controlled diet	Other: Dietary intervention - low catechin diet; The intervention will provide a nutritionally-matched beverage without catechins, for consumption alongside a low catechin diet tailored to participants calorie needs for weight maintenance.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Mean sum catechin metabolites	Mean difference in sum catechin metabolite concentration in response to the intervention, stratified by ODMA producers and non-producers.	Post 3-day intervention vs. post 3-day control

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Mean individual catechin metabolites	Mean differences in individual valerolactone and valeric acid concentrations in response to the intervention, stratified by ODMA producers and non-producers.	Post 3-day intervention vs. post 3-day control
Differences in microbiome profiles	Differences in microbiome profiles in response to the 3-day intervention.	Post 3-day intervention vs. post 3-day control
Difference in microbiome diversity	Differences in microbiome diversity in response to the 3-day intervention.	Post 3-day intervention vs. post 3-day control
Difference in microbial species abundance	Differences in microbial species abundance in response to the 3-day intervention.	Post 3-day intervention vs. post 3-day control

Collaborators and Investigators

• Sponsor: University of Maryland, College Park
• Collaborators: MaineHealth; University of Hawaii Cancer Research Center
• Investigators: Principal Investigator: Margaret Slavin, PhD, University of Maryland, College Park

Study record dates

Study Major Dates

• Study Start (Actual): December 7, 2023
• Primary Completion (Actual): May 8, 2025
• Study Completion (Actual): May 8, 2025

Study Registration Dates

• First Submitted: October 24, 2023
• First Submitted That Met QC Criteria: October 24, 2023
• First Posted (Actual): October 30, 2023

Study Record Updates

• Last Update Posted (Actual): June 22, 2025
• Last Update Submitted That Met QC Criteria: June 17, 2025
• Last Verified: June 1, 2025

More Information

Terms related to this study

• Keywords: Gut microbiome; Flavonoids; Isoflavones; Catechin
• Other Study ID Numbers: 2023-05787; 2022-67017-41032 (Other Grant/Funding Number: U.S. Department of Agriculture)

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No