What lives inside your gut could shape your immunity, mood, and disease risk, and it could hold the blueprint to better health

For decades, medicine looked at the human body in parts. The heart belonged to cardiologists, the brain to neurologists, and the digestive system to gastroenterologists. But scientists are increasingly discovering that one tiny ecosystem connects them all, the gut.Hidden inside the digestive tract are trillions of bacteria, fungi, viruses, and other microorganisms collectively called the gut microbiome. Once thought to be passive passengers, these microbes are now being viewed as active particip