Given the vast personal and economic burdens of psychiatric disorders, specifically mood and anxiety disorders, finding appropriate treatments for all those affected is critical. Due to the various presentations of psychiatric indications, no one treatment method is efficacious in all patients. Thus, a more personalized, but feasible treatment method is necessary for properly treating and preventing these disorders from becoming refractory and more burdensome. In recent years, there has been a growing appreciation for research in the field of the “gut-brain axis” (GBA), specifically as a target for psychiatric disorders. Researchers have found the gut to be influenced not only by similar determinants to that of psychiatric indications, but also highly modifiable using GBA treatments such as probiotics and fecal microbiota transplant (FMT). This is compelling evidence for the use of the GBA as a target for disorders such as depression and anxiety and for development of personalized treatment methods.