Multi-strain probiotic intervention in adults with depressive and anxiety symptoms: A 12-Week pilot study

Depressive and anxiety symptoms prevalent in major depressive disorder (MDD), that affects millions globally, with many patients showing incomplete response to standard treatments. This open-label pilot study evaluated the effects of a 12-week multi-strain probiotic supplementation on depressive and anxiety symptoms in 30 adults with depressive and anxiety symptoms (e.g., MDD, adjustment disorder, anxiety disorders). Participants received a daily capsule for eight weeks containing 11 bacterial strains (9.8 billion CFU), including Bifidobacterium animalis ssp. Lactis Lafti B94 (5 billion CFU) and Lactobacillus rhamnosus RO-11 (1.9 billion CFU). Outcomes were assessed using the Hamilton Depression Rating Scale (HDRS), Hamilton Anxiety Rating Scale (HAM-A), Generalized Anxiety Disorder 7-item scale (GAD-7), and Clinical Global Impression (CGI) scale at baseline, 4, 8, and 12 weeks following treatment. The intervention was well-tolerated, with minor gastrointestinal side effects in 10% of participants. Significant reductions were observed in HDRS (22.47 ± 6.95 to 8.83 ± 5.32, p < 0.01), HAM-A (32.27 ± 11.18 to 13.09 ± 10.49, p < 0.01), GAD-7 (15.33 ± 4.21 to 6.87 ± 5.37, p < 0.01), and CGI (4.53 ± 0.94 to 3.00 ± 1.65, p < 0.01) scores. Of note, females, participants with tertiary education, and married individuals showed greater improvements. The substantial reductions in these scores suggest probiotics may contribute in the reduction of depressive and anxiety symptoms, potentially via the microbiota-gut-brain axis, supporting further investigation in larger, controlled trials.