Eating too much sugary, highly processed food is bad for the body and the brain. It can alter blood flow to the brain and impair cognition. This is one reason why diabetes is a risk factor for cognitive dysfunction. Our brains need glucose to function and more natural whole foods provide a slower and more constant source of fuel. The Mediterranean Diet, in particular, has been shown to be brain-healthy. It focuses on a high intake of vegetables, fruit, cereals, unsaturated fats, and a low intake of dairy products and a moderate intake of fish.