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
