Our dietary choices affect our health and fitness in two ways: diet has a direct influence on the brain and other body parts and also influence the nature of our microbial populations in the gut. These two mechanisms frequently work together; a high salt diet can make high blood pressure worse and will influence the nature of our microbiota increasing inflammation – two issues which increase the risk of heart disease and stroke. Our dietary choices strongly affect our health through direct influence on all our organ systems, and the nature of our microbial communities has profound influence on our health and fitness. In order to have a diverse bacterial community we need a diverse diet with different good sources of nutritional support. Fiber-rich foods enhance the gut barrier and lower inflammation throughout the body. Good sources of fiber are reviewed in this chapter, along with recommendations for a plant-based diet with antioxidants, little meat, and low levels of saturated fat. High levels of sugar and salt intake, alcohol, and processed foods should be avoided. Fish consumption is advised and vitamin and mineral containing foods are also considered.