The aim of the study is to better understand the interplay between the intake of dietary fiber and intestinal bacteria, their metabolic activity and the effect on the intestinal barrier.

The effect of two different dietary fiber supplements is tested (arabinoxylan & ß-glucan versus inulin & fructooligosaccharides) in a randomized crossover intervention trial including healthy volunteers.

Inclusion Criteria:

• 18 to 65 years
• signed written informed consent
• willingness not to change the dietary pattern in the course of the study

Exclusion Criteria:

• BMI below 18 or above 30
• acute or chronic gastrointestinal symptoms
• neoplastic diseases
• very strict diets, including raw foodists and frutarians
• regular smoking (more than one box per day)
• intake of antibiotics, immunosuppressants, or any intestinal therapeutics three months prior to study begin
• supplementation of fibers three months prior to study begin
• simultaneous participation in another clinical study
• pregnancy / breastfeeding
• relevant violations of the study protocol
• intolerance to the fiber supplements (including wheat, oat, chicory)
• occurrence of relevant diseases (individual decision by study physicians)
• revocation of consent
• placement in a clinic or similar facility based on an official or court order