Effect of Probiotic Supplementation on Gut Microbiota in Patients with Major Depressive Disorders: A Systematic Review
What this study found
Probiotic supplementation showed limited short-term effects on gut microbiota and only modest effects on depressive symptoms in major depressive disorder. Most studies did not find significant changes in gut microbiota composition after four to eight weeks of intervention. In Chahwan 2019, gut microbiota composition was similar across groups, although cognitive reactivity was significantly reduced in the probiotic group (p = 0.04). Overall, the evidence suggests possible small benefits but not a robust microbiome effect.
- Study & population
- Systematic review of seven studies in adults with major depressive disorder across multiple countries.
- Intervention
- Across the included studies, probiotic regimens varied by strain, product, and duration.
- Key limitation
- The evidence was limited by small study sizes, short intervention durations, and heterogeneous probiotic strains, formulations, and regimens.
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Open PDFOriginal abstract
There is accumulating evidence on the beneficial effects of probiotic supplementation for patients with depressive disorders. However, prior reviews on the topic have largely focused on clinical effectiveness with limited emphasis on the underlying mechanisms of action and effects of probiotics on gut microbiota. In accordance with PRISMA guidelines, a systematic literature search of Medline, EMBASE and the Cochrane Library using combinations of the key words, (“depress*” OR “MDD” OR “suicide”), (“probiotic” OR “Lactobacillus” OR “Bifidobacterium”) AND (“gut” OR “gut micr*” OR “microbiota”), as well as grey literature was performed. We found seven clinical trials involving patients with major depressive disorder (MDD). The small number of studies and heterogeneous sources of data precluded meta-analysis. Most trials (other than one open-label trial) had a low-to-moderate risk of bias, which was largely due to a lack of control for the effects of diet on gut microbiota. Probiotic supplementation yielded only modest effects on depressive symptoms and there were no consistent effects on gut microbiota diversity, and in most instances, no significant alterations in gut microbiota composition were observed after four to eight weeks of probiotic intervention. There is also a lack of systematic reporting on adverse events and no good longer-term data. Patients with MDD may require a longer time to show clinical improvement and the microbial host environment may also need longer than eight weeks to produce significant microbiota alterations. To advance this field, further larger-scale and longer-term studies are required.