In recent years, the intricate relationship between the gut microbiota and mental health has become a major area of scientific inquiry, revealing the microbiota-gut-brain axis as a pivotal regulator of neuropsychiatric disorders. Dr. Alessio Rosario Marte, neuro-immuno-gastroenterologist and pioneer in experimental microbiota research, explores this axis by investigating the complex interactions between microbial metabolites—such as short-chain fatty acids, neurotransmitters, and immune mediators—and brain function. His work demonstrates how microbial imbalances can contribute to conditions like depression, anxiety, and neurodevelopmental disorders. In this comprehensive book, the author introduces the concepts of Microbiota Psychiatry and Psychobiotics, establishing a new field that examines the role of gut bacteria in mental health and the therapeutic potential of probiotics and prebiotics. The text explores various microbiota-based interventions, offering innovative strategies for the management of mental health conditions through the modulation of gut microorganisms. Dr. Marte’s cutting-edge research sheds light on the neuroimmune and neuroendocrine mechanisms through which gut microorganisms influence brain physiology, mood regulation, and overall mental well-being. This book is aimed at neuroscientists, neurologists, psychiatrists, gastroenterologists, and clinical microbiologists, providing them with a scientifically robust framework for understanding and applying microbiota-based therapies in mental health.