Your gut is home to an ecosystem of bacteria, viruses and fungi called the gut microbiome. That may sound bad, but it's really good for your overall health. When it's in balance, you feel great. But when something goes wrong, it rocks your world. Robynne Chutkan, MD, author of The Microbiome Solution, talks about how your digestive system works and why keeping it in good running order is one of the most important things you can do for your health.