Introduction
The gut microbiomeover 100 trillion microorganisms, communicates with the brain via the gut–brain axis, influencing mood, cognition, immunity, and stress regulation. Dysbiosis is linked to depression, anxiety, autism spectrum disorders, and neurodegenerative diseases, emphasising its critical role in mental and neurological health.
Microbial Mechanisms and Brain Chemistry
Gut bacteria produce neurotransmitters such as serotonin, dopamine, and GABA, and metabolites like short-chain fatty acids (SCFAs). These regulate neuroinflammation, strengthen the blood-brain barrier, and support neurogenesis. Serotonin affects mood, sleep, and appetite, while GABA calms the nervous system. Microbial metabolism of tryptophan, found in foods like eggs or turkey, supports neurotransmitter production.
Communication Pathways
The gut communicates with the brain through the vagus nerve, immune signalling, and microbial metabolites, influencing cognitive function and emotional regulation. SCFAs from fibre fermentation reduce inflammation and enhance brain function, illustrating the dynamic, bidirectional relationship between gut microbes and neural health.
Conclusion
The gut–brain axis is a critical therapeutic target. Supporting gut health through diet, probiotics, lifestyle, and emerging therapies can improve mood, cognition, and resilience, offering a path toward personalized mental health interventions.
