Evaluating the efficacy of probiotics in schizophrenia and depression: A meta-analysis of clinical outcomes and subgroup effects.

BackgroundSchizophrenia and depression are disabling mental disease conditions that have multifactorial pathophysiology involving the dysregulation of the gut-brain axis. Probiotics have been advocated as an adjunct therapy that could have an impact on psychiatric symptoms by normalizing the gut immune mechanisms.AimsThis meta-analysis evaluated whether probiotic supplementation improves psychiatric symptoms in patients with schizophrenia or depression.MethodologyA systematic search of multiple databases identified randomized controlled trials (RCTs) that tested probiotic interventions in these populations. Eligible studies were analyzed for pooled effect sizes, heterogeneity, and publication bias.FindingsThirteen RCTs (n = 893 participants) were included. Meta-analysis revealed no significant difference in PANSS score reduction between probiotic and placebo groups of schizophrenia patients (P = .546). However, a significant pooled standardized mean difference between intervention and control groups was found (P = .043). Significant heterogeneity was observed, and subgroup analyses indicated variations in outcomes based on geographic region and ethnicity. A potential moderating effect of vitamin D status was identified as a factor requiring future study.ConclusionCurrently, there is no evidence that probiotics consistently improve depression or schizophrenia. The significance of subgroup analysis raises questions and emphasizes the necessity of carefully planned, sufficiently powered studies to determine whether probiotic efficacy is influenced by particular populations, settings, or supplemental techniques.

• Publication year

  2025

• Venue

  Nutrition and Health

• Publication date

  2025-11-19

• Fields of study

  Medicine

• Identifiers
  DOI 10.1177/02601060251395942PMID 41259365
• External record

  Open on Semantic Scholar

• Source metadata

  Semantic Scholar, PubMed

• No claims are published for this paper.

• No concepts are published for this paper.

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