Cholesterol is a white soapy substance found in the tissues of humans and other animals. HDL cholesterol is helpful to your body; it produces cell membranes and some of your hormones. LDL cholesterol can be unhealthy for you. If too much of it collects on the walls of your arteries, it will interfere with the flow of blood to your heart and brain, which could lead to a heart attack or stroke. To avoid this problem, choose whole grains and foods with less saturated fat and more fiber.