Abstract
A revolution in the understanding of the pathophysiology of mental illness combined with new knowledge about host/microbiome interactions and psychoneuroimmunology has opened an entirely new field of study, the "psychobiotics". The modern microbiome is quite changed compared to our ancestral one due to diet, antibiotic exposure, and other environmental factors, and these differences may well impact our brain health. The sheer complexity and scope of how diet, probiotics, prebiotics, and intertwined environmental variables could influence mental health are profound obstacles to an organized and useful study of the microbiome and psychiatric disease. However, the potential for positive anti-inflammatory effects and symptom amelioration with perhaps few side effects makes the goal of clarifying the role of the microbiota in mental health a vital one.