Denver Garden Environment and Microbiome Study Disease (DGEM)

A Pilot Randomized Controlled Trial of Gardening as an Intervention to Reduce Risk of Cancer and Heart

An interdisciplinary team with extensive garden study experience conducted a pilot randomized controlled clinical trial to see whether gardening reduced risk factors for diseases like cancer and heart disease. The pilot trial will provide preliminary data on associations between human microbiome, diet, physical activity, and social interactions and the outcomes of weight status and key inflammatory biomarkers.

Study Overview

• Status: Completed
• Conditions: Physical Activity; Chronic Disease; Diet Modification; Weight Gain; Health Behavior; Lifestyle, Sedentary
• Intervention / Treatment: Behavioral: Community Garden Intervention

Detailed Description

The pilot study will lead to development of a future, large randomized controlled clinical trial, by fulfilling the following aims:

Pilot Aim 1: Demonstrate feasibility of recruitment and ability to perform study procedures.

Pilot Aim 2: Demonstrate the ability to measure accurately chronic disease risk factors such as diet, physical activity, weight gain, microbiome characteristics and inflammatory biomarkers.

Pilot Aim 3: Provide preliminary results on the efficacy of gardens as a preventive intervention, and estimates for a detailed power analysis for the proposed subsequent larger trial.

Aim 3a: Demonstrate that compared to non-gardeners, gardeners have 1) greater intake of fruits and vegetables; 2) better Healthy Eating Index (HEI); 3) lower Diet Inflammatory Index (DII); 4) reduced sedentary time and increased moderate-to-vigorous physical activity (MVPA); and reduced age-associated weight gain.

Aim 3b: For gardeners and non-gardeners, sample garden soil, gut, skin, and oral microbiome at six time points from April through September to characterize and compare bacterial load, pathogenic taxa, taxonomic diversity, relative dominance, indicator taxa, and metabolomic results.

Aim 3c: Demonstrate that gardening reduces inflammatory biomarkers linked to heart disease and cancer, including CRP, IL1b, IL4, IL6, IL10, and TNFa, and that the effect of gardening is mediated by diet, weight gain, physical activity and characteristics of the microbiome.

• Study Type: Interventional
• Enrollment (Actual): 16
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Colorado
    • Boulder, Colorado, United States, 80303
      • University of Colorado Boulder

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• Able to give informed consent in English or Spanish
• Aged 18 or over
• Currently on the wait list for a new garden
• Not have gardened in the past 2 gardening seasons

Exclusion Criteria:

• Is not able to complete the study requirements in Spanish or English
• Aged 17 or younger
• Has gardened in the past 2 gardening seasons

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Community Garden Intervention Group; Participants randomized to the Community Garden Intervention Group will receive the garden intervention. Participants will be assigned a plot for one season and will receive a standard package of services and amenities to support participation in the community garden, including seeds and transplants, tools, new garden classes and access to master community gardeners in Denver.	Behavioral: Community Garden Intervention; The investigators will recruit 30 prospective gardeners who have not been gardening for the past two years and who are listed on Denver Urban Gardens (DUG) wait lists. DUG randomly assigns people on each garden wait list to available plots, using a lottery. This creates a natural randomized experiment. Participants randomized to the garden intervention will receive a standardized garden resource package, which includes the following: A garden plot in a Denver Urban Garden; Seeds and plant starts; Introductory gardening workshop; Social events including garden-specific events and garden mentoring. The non-gardening group will remain on the DUG wait lists and will not receive these resources. Duration of the intervention is 1 year.
No Intervention: Wait List Control Group; The non-gardening group will remain on the DUG wait lists and will not receive the garden intervention.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in fruit and vegetable intake from baseline at 20 weeks	6 24-hour diet recalls will be collected at random	Measurements will occur during weeks 1-2 (3 random recalls) and weeks 18-20 (3 random recalls)
Change in sedentary time behavior from baseline at 20 weeks	Accelerometers will be adhered to thigh and collect data for 7 days	2 measurements over 6 months, T1 (Week 1) and T6 (Week 20)
Change in bacterial load from baseline at 20 weeks	Microbiome data will be collected six time points using 1 gut, 2 skin, and 1 oral samples	Every 3-4 weeks up to 20 weeks (Week 1, Week 4, Week 7, Week 10, Week 14, Week 18)
Change in moderate-to-vigorous physical activity (MVPA) from baseline at 20 weeks	Accelerometers will be adhered to thigh and collect data for 7 days	2 measurements over 6 months, T1 (Week 1) and T6 (Week 20)
Change in weight (kg) from baseline at 20 weeks	Objective measurements of weight will be collected	2 measurements over 6 months, T1 (Week 1) and T6 (Week 20)
Change in waist circumference from baseline at 20 weeks	Objective measurement of waist circumference	2 measurements over 6 months, T1 (Week 1) and T6 (Week 20)
Change in pathogenic taxa from baseline at 20 weeks	Microbiome data will be derived from 1 gut, 2 skin, and 1 oral samples	Every 3-4 weeks up to 20 weeks (Week 1, Week 4, Week 7, Week 10, Week 14, Week 18)
Change in taxonomic diversity from baseline at 20 weeks	Microbiome data will be derived from 1 gut, 2 skin, and 1 oral samples	Every 3-4 weeks up to 20 weeks (Week 1, Week 4, Week 7, Week 10, Week 14, Week 18)
Change in relative dominance from baseline at 20 weeks	Microbiome data will be derived from 1 gut, 2 skin, and 1 oral samples	Every 3-4 weeks up to 20 weeks (Week 1, Week 4, Week 7, Week 10, Week 14, Week 18)
Change in indicator taxa from baseline at 20 weeks	Microbiome data will be derived from 1 gut, 2 skin, and 1 oral samples	Every 3-4 weeks up to 20 weeks (Week 1, Week 4, Week 7, Week 10, Week 14, Week 18)
Change in Inflammatory biomarkers from baseline at 20 weeks	Samples include hs-CRP, TNF-alpha, IL1b, IL4, IL6, IL10	20 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in HbA1C from baseline at 20 weeks		20 weeks
Change in blood pressure from baseline at 20 weeks		20 weeks
Change in lipid profile from baseline at 20 weeks	Including LDL, HDL, total cholesterol, triglycerides	20 weeks

Collaborators and Investigators

• Sponsor: University of Colorado, Boulder
• Investigators: Principal Investigator: Jill S Litt, PhD, University of Colorado, Boulder

Study record dates

Study Major Dates

• Study Start (Actual): June 2, 2016
• Primary Completion (Actual): December 15, 2017
• Study Completion (Actual): December 30, 2017

Study Registration Dates

• First Submitted: February 17, 2017
• First Submitted That Met QC Criteria: March 17, 2017
• First Posted (Actual): March 24, 2017

Study Record Updates

• Last Update Posted (Actual): May 7, 2021
• Last Update Submitted That Met QC Criteria: May 4, 2021
• Last Verified: May 1, 2021

More Information

Terms related to this study

• Keywords: Physical Activity; Obesity; Microbiome; Diet; Inflammatory biomarkers; Health Behavior Change; Neighborhood; Pilot Randomized Controlled Trial; Community Garden
• Additional Relevant MeSH Terms: Pathologic Processes; Disease Attributes; Body Weight; Body Weight Changes; Chronic Disease; Weight Gain
• Other Study ID Numbers: 16-0138, 16-0424

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