Probiotic trials reported lower depression scores, with varied results
Compared with placebo, probiotics lowered depression ratings in pooled randomized trials. Differences across trials and missing participant details limit what this result says about individual experiences.
Based on the published abstract. The full paper may contain additional methods, results and limitations.
The 30-second takeaway
The pooled trials favored probiotics for depressive symptoms, including scores on the Hamilton Depression Rating Scale, a questionnaire used to rate symptom severity. However, results varied across studies. The abstract does not identify participant eligibility, treatment length or how score changes translated into everyday experiences, leaving the practical meaning uncertain.
The abstract does not provide participant characteristics or intervention durations. It also reports variation between trials, which limits how confidently the pooled result can describe a particular probiotic product or patient group.
What researchers found
Hamilton Depression Rating Scale
Probiotics versus placebo: pooled score mean difference −3.27 (95% confidence interval −6.42 to −0.12). Treatment duration was not reported in the abstract.
What the review measured
The review combined randomized trials examining depression symptoms and possible biological changes. Depression rating scores were the central pooled outcome; changes in gut microbes or inflammatory measurements were separate findings, rather than direct measures of symptom relief.
What remains unresolved
The authors highlighted particular strains and mixtures, but the abstract does not present direct comparisons establishing which product works better. Its proposed biological explanations also do not establish which changes account for the reported symptom differences.
The original publication
An updated systematic review and appraisal of the pathophysiologic mechanisms of probiotics in alleviating depression.
Sulaiman NNY, Mohamad Nizam NB, Mohd Noor NA et al.
Nutr Neurosci · 2025
- PubMed ID
- 40669008
- Record checked
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