Systematic review and meta-analysis of gut microbiota in schizophrenia versus healthy controls

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International journal of molecular sciences Published May 27, 2026 Medically reviewed May 27, 2026 Study authors: Militaru Andreea-Mihaela, Pietreanu Arina Cipriana, Trifu Simona, Popa Gabriela Loredana PubMed ↗ DOI ↗ By Dr. Ji-eun Park, MD · Brain, Mind & Pain

Key Takeaway

Note substantial heterogeneity and limited confounder control in this meta-analysis of schizophrenia gut microbiota.

This systematic review and meta-analysis examined gut microbiota composition, including alpha diversity, beta diversity, and taxonomic composition, in individuals with schizophrenia compared to healthy controls. Forty-eight studies met inclusion criteria for qualitative synthesis, with 14 providing sufficient data for random-effects meta-analyses. The review did not report specific effect sizes or absolute numbers for the outcomes analyzed.

The meta-analysis found no statistically significant differences between patients and controls regarding alpha diversity indices, which included Shannon, Simpson, Chao1, ACE, and Observed measures. However, significant differences were observed in beta diversity, indicating distinct microbial community compositions between the groups. Taxonomic composition analysis showed a depletion of short-chain fatty acid-producing taxa, such as Lachnospiraceae, and an enrichment of pro-inflammatory taxa, such as Proteobacteria, in the patient group.

The authors note substantial heterogeneity and limited control for key confounders, including antipsychotic medication, diet, and lifestyle factors. These limitations suggest that the biological interpretation and causality of the observed associations require further investigation. The review highlights candidate taxa that may warrant further investigation in biomarker-focused studies and microbiome-based therapeutics.

Practice relevance is tempered by the need for cautious interpretation. The findings should be interpreted cautiously, and clinicians should avoid overstating biological interpretations or causal links based on this evidence. No safety data or adverse events were reported in the included studies.

Study Details

Study typeMeta analysis

EvidenceLevel 1

PublishedMay 2026

PMID42196583

View Original Abstract ↓

Emerging evidence implicates the gut-brain axis in the pathophysiology of schizophrenia, yet literature regarding specific microbiome alterations remains inconsistent. This study aims to synthesize evidence on gut microbiota diversity and taxonomic composition in individuals with schizophrenia compared to healthy controls. Unlike prior meta-analyses, this study integrates quantitative alpha diversity synthesis with cross-taxonomic qualitative analysis and contextualizes findings within functional frameworks of the gut-brain axis, highlighting the methodological heterogeneity that limits biological interpretation. A systematic review and meta-analysis were conducted following PRISMA 2020 guidelines. Electronic databases (Web of Science, PubMed, MDPI) were searched for observational studies published between 2017 and 2025. Forty-eight studies met inclusion criteria for qualitative synthesis, with 14 providing sufficient data for random-effects meta-analyses of alpha diversity. Meta-analyses revealed no statistically significant differences in alpha diversity indices (Shannon, Simpson, Chao1, ACE, Observed) between patients and controls, despite high heterogeneity. Conversely, beta diversity analyses generally demonstrated significant differences in microbial community composition. Taxonomic synthesis identified recurrent but heterogeneous dysbiotic patterns characterized by the depletion of short-chain fatty acid-producing taxa (e.g., , , Lachnospiraceae) and enrichment of pro-inflammatory taxa (e.g., Proteobacteria, ). Schizophrenia is associated with evidence of compositional alterations and functional shifts rather than a global loss of microbial richness. These findings highlight candidate taxa that may warrant further investigation in biomarker-focused studies and microbiome-based therapeutics. However, these findings should be interpreted cautiously due to substantial heterogeneity and limited control for key confounders such as antipsychotic medication, diet, and life-style factors.