In this study the effects of a fibre dietary supplement on the gut microbiome in healthy adults will be investigated. For this purpose, a 14-day dietary supplementation with inulin or placebo (maltodextrin) will be carried out in healthy adults. The main objective of the study is to investigate inulin-induced changes in gut bacterial composition, bacterial gene expression, bacterial metabolite production and associated immune system changes.

Healthy volunteers between the age of 18 and 60 will be recruited. In the first week of the study baseline blood and stool sampleswill be collected and nutritional information recorded. The participants will then take 15g of inulin or maltodextrin twice per day for 14 consequetive days. Blood and stool samples will be collected daily during the inital phase of the intervention and again at the end of the intervention.

From the stool samples bacterial nucleic acids will be isolated and used for metagenomic and transcriptomic analysis. The blood samples will be used to analyse for markers of barriere function and for analysis of immune cells.

Inclusion Criteria:

• Men and women in a 1:1 ratio
• Age 20 - 60 years
• Body Mass Index 18.5 - 34.9 kg/m2

Exclusion Criteria:

• Arterial hypertension, diabetes mellitus, known cardiovascular disease requiring treatment (e.g. coronary heart disease, stroke).
• Known end-organ damage to the brain, heart or kidneys
• Chronic kidney disease, need for dialysis
• Diseases or functional disorders that, in the opinion of the study doctor, preclude participation in the study
• Acute infections
• Malnutrition
• Antibiotics in the previous 4 weeks
• Regular consumption of probiotics or prebiotics
• Allergies
• Change in bodyweight of more than 2 kg in the previous 3 months
• Inability to uderstand the studie aims and study procedures
• Drug or alcohol abuse

All participants and study staff are blinded