Background: Gut microbiome has an important influence not only in the gastrointestinal function, but also in the immune modulation, intercellular and neuro-endocrine signaling, and in the communication between the Enteric Nervous System and the Central Nervous System, the so called Gut-Brain Axis. Methods: The aim of this paper was to search literature from the databases PubMed, Scielo and Google Scholar to identify recent knowledge regarding the relations between the microbiome and the Gut-Brain Axis function. Findings: Microbiome is stablished since the very first days of life, and suffers the influence of several external factors. Throughout the first years of life, a symbiotic relationship with the host is stablished. Since then, the gut microbiome provides a great influence in the communication of the Gut-Brain Axis. Modifications on its profile could be involved in genesis of mental morbidities, like schizophrenia, depression, autism, and also exacerbation on stress responses. Conclusions: Early life stimulations are implicated with the gut microbiome bacteria profile, which outcomes are for life. Modifications in the microbiome profile could result in impairment of the development of several organic systems, specially on neurodevelopment, rising risk of mental diseases in the adulthood
