This randomized, double-blind, placebo-controlled pilot study will evaluate the effects of four weeks of supplementation with a probiotic on mental health in healthy adults aged 18-30 years. Participants will be randomized to receive either probiotic or placebo and will complete study assessments at baseline and end of intervention, and will complete a range of behavioral, physiological, and questionnaire-based assessments before and after the intervention. The primary objective is to assess the effect on emotional reactivity measured in a virtual reality scenario at the end of the intervention. This exploratory study is intended to generate data to inform future clinical research.
18-30 years of age
Native-level Danish language skills
No current psychiatric illness, confirmed with the Presence State Examination (PSE) and the Standardized Assessment of Personality (SAPAS)
No previous history of severe psychiatric illness, including bipolar disorder, recurrent unipolar depression, psychosis spectrum disorders, personality disorders, autism spectrum disorders, or attention deficit (hyperactivity) disorder (ADHD/ADD), confirmed with PSE and SAPAS. Participants may still be included if they have a history of a single depressive episode, or have experienced symptoms of anxiety, stress, or burnout more than 6 months ago.
Recent use of probiotics (within the past 4 weeks)
Use of antibiotics within the past 3 months
Smoking, chewable tobacco, vaping, or use of other nicotine products
Neurological disorders (including dementia)