We need cholesterol, a fatty, waxy substance because our cells use it to form the membrane - a critical part of the cell. But because it is fatty, it does not dissolve in the blood, but is carried to your cells by certain proteins. We get concerned about cholesterol when there is too much of it, particularly when there is too much "Low-Density Lipoprotein" or LDL cholesterol. This type of cholesterol is one of the major risk factors for coronary heart disease. On the other hand, there is High-Density or HDL cholesterol, which is "good" cholesterol, and good levels of HDL are associated with less risk of stroke and heart attack.