Probiotics showed a small psychological symptom benefit in healthy workers
The review found modest symptom changes, limited sleep evidence and no significant effect on an inflammation marker.
Based on the published abstract. The full paper may contain additional methods, results and limitations.
The 30-second takeaway
The pooled trials suggest a small improvement in symptoms of depression, anxiety and stress among healthy workers taking probiotics. This does not establish treatment effects in people with psychiatric diagnoses, who were excluded. Evidence was too limited to draw firm conclusions about sleep, and the review found no statistically significant change in the inflammation marker C-reactive protein.
The authors describe the evidence as preliminary. The abstract does not specify comparison conditions or assessment times, and its eligible population excluded people with psychiatric disorders.
Variation across trials
Trials used different probiotic strains, amounts and supplementation periods. This variation may help explain differences between study results, and the review does not identify a particular formulation or schedule as best.
A separate biological outcome
Cortisol levels also decreased in the pooled analysis. That finding concerns a physiological marker of stress; it does not, by itself, establish a meaningful improvement in mental health or daily functioning.
The original publication
Probiotic intake and mental health in healthy working adults: a systematic review and meta-analysis of randomized controlled trials.
Ben Fredj S, Kechiche H, Chouchen A et al.
BMC Psychol · 2026
- PubMed ID
- 41501907
- Record checked
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