The liver manufactures cholesterol (ko-LES-ter-all) at the precise rate required by the body. It's used to build important structures like cell membranes, hormones, and Vitamin D. Since cholesterol is naturally waxy and doesn't mix well with blood, the body coats cholesterol molecules with protein. This enables them to travel easily through the bloodstream. The encapsulated cholesterol then becomes either a high-density lipoprotein (LIP-o-pro-teen) or HDL (H-D-L), or a low-density lipoprotein, LDL (L-D-L). In general, the bloodstream carries more LDL than HDL. LDL is also referred to as bad cholesterol, because when the body has an oversupply of it, it's generally deposited along arterial (art-EAR-ee-al) walls. This build up can make the arteries harden and become narrow so that they aren't able to carry enough blood to the heart. A decreasing blood supply means less oxygen to the heart, which in turn may cause chest pain or angina (an-JIE-nuh), a heart attack, or myocardial infarction (my-o-KAR-dee-al in-FARK-shun). So the bloodstream's level of LDL is directly related to risk of coronary heart disease. There are several factors that seem to affect the amount of LDL in the blood. Controllable factors include: specific types of food eaten, proximity to ideal weight, and physical activity. The main uncontrollable factors are heredity, age, race, and gender. A physician can perform a simple blood test to determine blood levels of LDL and HDL and help evaluate heart disease risk. If you're concerned about your cholesterol level, or would like to know more about controlling cholesterol levels, contact your health care provider.