Probiotic Effects on the Microbe-brain-gut Interaction and Brain Activity During Stress Tasks in Healthy Subjects

The aim of this study is to determine if and how the "Probiotic Product" affects functional brain responses in healthy subjects during an emotional- and arithmetic stress task, respectively and in terms of microbe-brain-gut interactions.

In this randomized double-blind placebo-controlled study, n=22 healthy subjects will receive the following interventions in a crossover fashion, separated by a 4-week wash-out period: 1) Probiotic Formula, 2) placebo. After baseline assessments, study participants will start with a 4-week intervention with the study product or the placebo, followed by a 4-week wash-out period and a subsequent 4-week intervention period (placebo or study product, respectively). fMRI (functional magnetic resonance imaging) scanning during two validated stress tasks will be performed after each of the intervention periods (week 4 and week 12). At the same time points and in addition on the days before the 1st and 2nd intervention (baseline 1 and 2), saliva, blood and faecal samples will be collected. Questionnaire data will be collected and psychological tests and instruments will be performed. For one week at baseline and during the intervention periods (last week), subjects will wear actigraphs to record their physical activity and help assess sleep quality. At baseline, subjects will undergo a carbon dioxide (CO2) challenge test as well as a food diary to record dietary habits.