Abstract
BACKGROUND: The gut microbiome communicates bidirectionally with the brain, linking the gut to psychological phenomena such as stress, depression, and anxiety. Probiotics, or ingestible supplements containing billions of mutualistic bacteria, have demonstrated the mechanistic potential to influence mood; however, few studies have experimentally examined the acute effects of these compounds on individuals not recruited for psychopathology or gut dysfunction. The present study hypothesized reductions in stress, anxiety and depression symptoms following an acute, one week dosing period of B. longum intake. METHODS: The efficacy of a one-week period of orally administered B. longum was tested utilizing a double-blind experimental design. Participants were randomly assigned to either placebo or probiotic capsules under double blinded conditions and completed the Perceived Stress Scale (PSS), the Center for Epidemiological Studies Depression scale (CES-D), and the State-Trait Anxiety Inventory (STAI Y2 form) to assess for differences before and after one-week intervention. RESULTS: No significant reduction in symptoms between groups over the one-week period was found. CONCLUSIONS: These findings suggest that 7-days of B. longum does not reduce stress, depressive symptoms, or anxiety in generally healthy young adults.