The Mind-Gut Connection: How the Hidden Conversation Within Our Bodies Impacts Our Mood, Our Choices, and Our Overall Health

by Emeran Mayer

Gut microbiota have also been linked to depression, which is the second leading cause of disability in the United States. The drugs used most often to treat depression are the so-called selective serotonin reuptake inhibitors such as Prozac, Paxil, and Celexa. These drugs boost the activity of the serotonin signaling system, which psychiatry had long thought is exclusively located in the brain. However, we know today that 95 percent of the body’s serotonin is actually contained in specialized cells in the gut, and these serotonin-containing cells are influenced by what we eat, by chemicals released from certain species of gut microbes, and by signals that the brain sends to them, informing them about our emotional state. What is most remarkable is that these cells are tightly connected to sensory nerves that signal directly back into the brain’s emotion regulating centers, making them an important hub within the gut-brain axis. Because of this strategic location it is likely that gut microbes and their metabolites play an important and largely unrecognized role in the development of depression as well as its severity and length—an intriguing possibility that, if confirmed in controlled studies, could create new opportunities for the development of more effective treatments, including specific dietary interventions.