Effects of gut microbiota on the brain: implications for psychiatry

1In fact, there are more bacteria in the gut than there are somatic cells in the body. These resident bacteria are referred to as commensal microbiota, and their arrival during the first few postnatal days sets up a symbiotic association that is necessary and crucial to normal physiology. This lifelong association is essential to host pathogen defence and plays an important role in nutrient uptake and metabolism. 2 Immunologists have been aware of this system and its importance to the development of the muscosal and systemic immune systems for a long time. 3,4 What is new and noteworthy is emerging evidence that gut microbiota influence behaviour and central nervous system (CNS) function. 5 This commentary provides a brief overview of research related to gut‐brain communication in a context that allows neuroscientists and psychiatrists to take note and consider the role of microbiota in their research related to CNS function and behaviour. Colonization of the gastrointestinal tract, predominantly the colon, begins at birth, continues in early development and remains throughout life. The early profile of microbiota is influenced by genetics and postnatal environmental exposure. Several bacterial phylotypes are distributed in the human gastrointestinal tract and, although each person’s microbial profile is distinct, relative abundance and distribution along the gastrointestinal tract of these bacterial phylotypes is similar among healthy individuals.