Inflammation in the gut has been identified as one of the culprits in a long list of chronic illnesses, including colorectal cancer, diabetes, rheumatoid arthritis, and Crohn’s disease. Cutting-edge research is also revealing a pathway between the gut and the brain, suggesting a possible explanation for Alzheimer’s disease, Parkinson’s disease, and a host of mood disorders. Investigators are digging deeper into the mechanisms that explain those links, intrigued by the protective functions of the microbiome and determined to understand what causes the imbalances that undermine that protection. What does the latest science tell us, and where do we go next with our studies?