Background: Over recent years, growing evidence points to gut dysbiosis as a potential factor in the development of several neuropsychiatric illnesses. However, the significant discrepancies between studies has made it necessary to compile new information, elucidating the mechanisms behind gut-brain connection.

Objectives: This review attempts to incorporate the most recent data and noteworthy findings by focusing on research conducted within the past five years, ultimately offering insights into the complex interaction between gut microbiota and mental health.

Findings of the review: There is evidence linking psychiatric disorders to dysbiosis. Studies on anorexia nervosa have shown an increase in inflammatory taxa and a decrease in helpful bacteria like Bifidobacterium.

Probiotics such as Bifidobacterium breve and Lactobacillus plantarum have demonstrated promise in reducing depressive symptoms. Moreover, they have been shown to lower oxidative stress biomarkers in schizophrenia and anxiety, although the effects on symptom severity are still unclear. Changes in Blautia and Streptococcus have been linked to sleep disruptions, suggesting a complex relationship between gut health and sleep regulation. Furthermore, it has been demonstrated that microbial metabolites affect the synthesis of neurotransmitters.