Oral Methods of Microbiota Manipulation for Depression Symptoms: A Systematic Review: Méthodes orales de manipulation du microbiote pour traiter les symptômes de dépression : Une revue systématique.
Anna Oprea, Joe Steinman, Grace Huang et al.
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In 30 seconds
This systematic review examined completed parallel-arm randomised controlled trials of oral microbiota manipulation and depressive symptoms in adults not taking antidepressants. It included 66 trials; 34 reported significant intervention–control differences in depressive symptoms. Interventions included probiotics, prebiotics, synbiotics and oral faecal microbiota transplantation, with substantial variation in study design, intervention composition, administration and outcome measures. This heterogeneity prevented statistical synthesis or meta-analysis, and the authors concluded that the evidence does not support concrete conclusions about whether these approaches are viable alternatives for adults experiencing depressive symptoms.
Key findings
- Of 66 included randomised trials, 34 reported significant differences in depressive symptoms between intervention and control groups.
- Interventions comprised probiotics in 54 trials, prebiotics in seven, synbiotics in eight and oral faecal microbiota transplantation in two.
- Variation in interventions, measures and outcomes precluded statistical synthesis or meta-analysis.
Why it matters
Interest in microbiota-based approaches reflects the limitations and acceptability concerns associated with existing depression treatments. This review shows that although many trials have reported differences in depressive symptoms, their varied methods and outcomes make the overall evidence difficult to interpret. Standardised study design and reporting would help determine whether oral microbiota manipulation has a reliable role in depression care.
What to keep in mind
The included trials were highly heterogeneous, preventing meta-analysis and firm conclusions about efficacy.