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

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.

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