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

Study Overview
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Brief Summary
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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.

Detailed Description
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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.

Official Title
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Food Derived Bacteria and Their Role in Treating Disease

Conditions
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Healthy

Intervention / Treatment
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* Other: Diet


Participation Criteria
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Eligibility Criteria
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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

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 65 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: Other
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Specified Diet 1 - Microbial Diet<br>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<br>* 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.<br>|
| Active Comparator: Specified Diet 2 - Non-microbial Diet<br>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<br>* 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.<br>|

What is the study measuring?
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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) |