What is your cholesterol number and why is it important? Cholesterol is a fat-like substance that is carried by the blood to all parts of your body. Though some of the cholesterol comes from food, the majority is made by your body. . If there is too much cholesterol in your blood stream, there is a chance that it will eventually collect in the walls of the blood vessels and, in time, even clog the blood vessel(s). If that should happen, you could have a heart attack or a stroke.