The Impact of Food on Gut Microbiome Composition - a Clinical Trial Determining the Influence of Diet in Gut Microbiome Colonisation and Host Health (FIG)

Food Derived Bacteria and Their Role in Treating Disease

The goal of this clinical trial is to examine the impact of food derived bacteria on gut microbiome composition and host health. The main questions it aims to answer are:

• what is the the rate of gastrointestinal colonisation of food derived bacteria?
• what is the contribution of food derived bacteria to gut microbiome stability?

Participants will complete a cross over feeding study of dietitian designed meals of known microbial load and will be asked to provide stool and blood samples for analysis.

Study Overview

• Status: Completed
• Conditions: Healthy
• Intervention / Treatment: Other: Diet

Detailed Description

To understand the role and stability of food derived bacteria in impacting microbiome composition, 20 healthy participants will be recruited for this single site double blinded randomised controlled crossover pilot trial. The study is divided into four 14 day diet phases - baseline habitual, specified diet 1, habitual washout and specified diet 2. Participants will be randomly assigned to receive a microbial or non-microbial diet in specified diet 1 phase. Each participant will then crossover to receive the alternative diet in the specified diet 2 phase. The microbial and non-microbial diets will be identical except for the removal of naturally occurring food derived bacteria in non-microbial diet. At the commencement of the study and at the end of each diet phase, participants will attend a research clinic to undergo comprehensive clinical and anthropometric assessment and dietary evaluation.

• Study Type: Interventional
• Enrollment (Actual): 25
• Phase: Early Phase 1

Contacts and Locations

Study Locations

• Australia
  • Victoria
    • Notting Hill, Victoria, Australia, 3168
      • BASE Facility

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

• Have no genetic conditions (e.g. Prader Willi or Down's Syndrome)
• Not diagnosed with a significant medical conditions (e.g. irritable bowel syndrome, inflammatory bowel disease or type 1/2 diabetes)
• Do not require drug-therapy (e.g. steroids or insulin or antibiotics)
• Not taking dietary supplements, probiotics, prebiotics, symbiotics or fibre supplementation
• Any condition that will affect participation in the study
• Not pregnant, planning a pregnancy or breastfeeding
• Able to complete a two-month dietary study and agree to eating all meals provided
• Have no dietary allergies or dietary restrictions that prevent consumption of provided study meals
• Open bowels regularly - mostly daily
• Able to read, write and understand English

Exclusion Criteria:

• Dietary concerns identified by dietitian
• Aged less than 18 years and older than 65 years
• Diagnosed with a medical condition that requires drug therapy
• Taking medications or supplements known to alter gastrointestinal microbiota
• Women who are pregnant, planning a pregnancy or breastfeeding
• Anyone with a diagnosed gastrointestinal condition/disease e.g. irritable bowel syndrome or inflammatory bowel disease
• Known dietary allergy and/or intolerance, follows a vegan or vegetarian diet, or has coeliac disease
• Anyone with a preference for specific food avoidance or exclusion of certain ingredients in habitual diet
• Unable to tolerate blood collection procedures
• Unable to provide regular stool samples throughout the study

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Other
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Quadruple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Specified Diet 1 - Microbial Diet; Participants provided with a typical Australian diet including all food groups as described by the Australian Guide to Healthy Eating without any dietary exclusions. Meals have been designed by researchers and dietitians and prepared by professional chefs.	Other: Diet; Participants will be assigned prospectively to microbial or non-microbial diet for first phase of trial and will then cross over to the alternate diet following a washout period.
Active Comparator: Specified Diet 2 - Non-microbial Diet; Diet provided to participants is identical to Specified Diet 1 however after cooking and packaging, food for this arm will be sterilised by irradiation in line with International Organisation for Standardisation (ISO) standards and Australian code of good manufacturing practice.	Other: Diet; Participants will be assigned prospectively to microbial or non-microbial diet for first phase of trial and will then cross over to the alternate diet following a washout period.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Characterisation of gut microbiome	Sequencing and bacterial culturing of stool samples	Day 1, 4, 7, 11 and 14 of each phase

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Participant body mass index (BMI)	Assessed independently using height and weight measurements and appropriate formula	BMI will be calculated on day 14 (at end of each diet phase (fortnightly))
Participant standing height	Measured by stadiometer	Height will be measured on day 14 (at end of each diet phase (fortnightly))
Participant weight	Measured using balance scales	Weight will be measured on day 14 (at end of each diet phase (fortnightly))
Participant waist circumference	Measured using standard measuring tape	Baseline day 1 and end of each 14-day diet phase
Participant Hip circumference	Measured using standard measuring tape	Baseline day 1 and end of each 14-day diet phase
Resting systolic and diastolic blood pressure	Measured using digital blood pressure monitor	Blood pressure will be measured on day 14 (at end of each diet phase (fortnightly))
Mental Health Assessment	Perceived Stress Scale survey completed by participants	Completed at day 1 and end of study (day 56)
Dietary compliance	Measured by participant completed daily diet checklist noting the amount of food they consumed of provided meals during specific diet 1 and 2 phases	Day 1 to Day 14 of specified diet 1 and diet 2 phases
Habitual dietary intake	Using research food diary mobile phone application	Daily throughout 14-day baseline habitual and habitual washout phases
Changes in physical activity levels	Using International Physical Activity Questionnaire - Short Form (IPAQ-SF)	Completed at each of each 14-day diet phase
Glucose levels	Blood samples collected will be assessed for glucose levels	Blood collected at baseline day 1 and day 14 of each phase (fortnightly)
Lipid studies	Blood samples collected will be assessed for lipid studies	Blood collected at baseline day 1 and day 14 of each phase (fortnightly)
Irritable Bowel Syndrome-Severity Scoring System (IBS-SS)	Completion of Irritable Bowel Syndrome-Severity Scoring System (IBS-SS)	End of each 14-day diet phase
Gastrointestinal symptomatology	Completion of Gastrointestinal Symptom Rating Scale (GSRS)	Baseline day 1 and day 14 of each diet phase (fortnightly)
Bowel movement	Completion of Bristol Stool Chart questionnaires	Baseline day 1 and day 14 of each diet phase (fortnightly)
End of study optional semi-structured interview	Interview participants to assess challenges of adhering to study and compliance	End of study (at least 8 weeks post-randomisation)

Collaborators and Investigators

• Sponsor: Monash University
• Investigators: Principal Investigator: Dr. Sam Forster, Hudson Institue, Monash University

Study record dates

Study Major Dates

• Study Start (Actual): June 16, 2023
• Primary Completion (Actual): November 28, 2023
• Study Completion (Actual): November 28, 2023

Study Registration Dates

• First Submitted: July 19, 2023
• First Submitted That Met QC Criteria: August 3, 2023
• First Posted (Actual): August 14, 2023

Study Record Updates

• Last Update Posted (Actual): April 24, 2025
• Last Update Submitted That Met QC Criteria: April 21, 2025
• Last Verified: April 1, 2025

More Information

Terms related to this study

• Other Study ID Numbers: RES-21-0000-602A

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: Applications made for reasonable access to de-identified study data will be made on a case-by-case basis by the study team. Data-specified appropriate analysis will be determined when required. Applications for data accessibility will be made on a case-by-case basis by study team.
• IPD Sharing Time Frame: Accessibility to individual participant data (IPD) and supporting information will be determined at a later date and on a case-by-case basis
• IPD Sharing Access Criteria: Accessibility will be assessed on a case-by-case basis
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL

Drug and device information, study documents

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