Next-generation microbiome therapeutics: psychobiotics and fecal microbiota transplants for mental health treatment

Abstract

The human gastrointestinal tract (GIT) harbors a diverse microbial community, collectively referred to as gut microbiota, which plays an essential role in maintaining host physiology, metabolism, immune function, and neurobehavioral processes. Mounting evidence highlights the importance of the bidirectional Gut–brain (GB) axis, through which gut microbes influence neural signalling, stress response, and emotional regulation. Dysbiosis of this axis has been associated with psychiatric, neurodevelopmental, and neurodegenerative disorders, such as anxiety, autism spectrum disorder (ASD), major depressive disorder (MDD) and schizophrenia. A growing area of research has identified psychobiotics—live microorganisms with psychotropic potential—as promising therapeutic agents for mental health conditions. These microbes exert their effects through multiple mechanisms, including modulation of neurotransmitter production, short-chain fatty acid (SCFA) signalling, immune regulation, and hypothalamic–pituitary–adrenal (HPA) axis stabilization. Preclinical and clinical studies provide supportive evidence for their antidepressant and anxiolytic effects, although large-scale, long-term trials remain limited. In parallel, fecal microbiota transplantation (FMT) has emerged as a potential strategy to restore microbial balance and improve psychiatric symptoms. Early findings demonstrate its role in modulating immune pathways, such as NLRP3 inflammasome signalling, and neurotrophic factors via gut microbial reshaping. Together, psychobiotics and FMT represent next-generation microbiome therapeutics that may complement conventional psychiatric interventions. This review synthesizes current evidence and highlights the future potential of microbiome-based strategies in treating mental health disorders.