Many people are oblivious to the fact that when mental health is affected, the root of the problem is not solely in the brain. Instead, one or more of the body’s connections with the brain has gone awry. We know that these connections are quite real. Depression can affect the heart. Pathologies of the adrenal gland can throw you into a panic. Infections darting through your bloodstream can make you seem like you have lost your mind. Maladies of the body frequently manifest as turbulence of the mind. But while medical illness can cause psychiatric symptoms, we now know that the story goes even deeper. Subtle changes in distant parts of the body can change the brain, too. The most profound of these distant relationships is between the brain and the gut. Centuries ago, Hippocrates, the father of modern medicine, recognized this connection, warning us that “bad digestion is the root of all evil” and that “death sits in the bowels.” Now we are figuring out how right he was. Though we are still on the forefront of discovery, in recent years the gutbrain connection has provided one of the richest, most …