For much of modern medicine, the brain and the gut were treated as separate systems. Mental health was studied through neurotransmitters, cognition, and psychology, while digestion was viewed as a mechanical process of nutrient breakdown and absorption. Over the past two decades, this separation has steadily eroded. Research now shows that the gut and brain are in constant communication, influencing not only digestion and immunity, but also mood, motivation, and behavior. At the center of this relationship is the gut brain axis, a bidirectional communication network linking the central nervous system with the gastrointestinal tract and its microbial inhabitants. As understanding of this system deepens, microbial imbalance in the gut…