Probiotics and Anxiety/Depression: A Systematic Review
Huang R, Wang K, Hu J
Journal of Affective Disorders • January 2019
Plain Language Summary
This review of 34 studies found that probiotic supplements can help reduce both anxiety and depression symptoms, supporting the “gut-brain connection” theory. The benefits were more pronounced in people with clinical anxiety or depression compared to healthy individuals. Taking multi-strain probiotics for at least 8 weeks appears most effective. Scientists believe gut bacteria influence brain chemistry through various pathways including the vagus nerve and immune system.
Key Findings
- 1Probiotics significantly reduced both anxiety and depression symptoms
- 2Effects were stronger in clinical populations vs healthy individuals
- 3Multi-strain probiotics showed better results than single strains
- 4Treatment duration of 8+ weeks showed stronger effects
- 5Lactobacillus and Bifidobacterium strains were most studied
Abstract
This systematic review and meta-analysis investigated the effects of probiotic supplementation on symptoms of anxiety and depression through the gut-brain axis. The analysis included 34 controlled trials.
Study Limitations
- Heterogeneity in probiotic formulations
- Varying assessment tools for anxiety/depression
- Mechanisms not fully elucidated
- Need for more RCTs in clinical populations