A fatty substance present in all parts of the body. It is a component of cell membranes and is used to make vitamin D and some hormones. Some cholesterol in the body is produced by the liver and some is derived from food, particularly animal products. A high level of cholesterol in the blood can help cause atherosclerosis and coronary artery disease. In the blood, cholesterol is bound to chemicals called lipoproteins. Cholesterol attached to low-density lipoprotein (LDL) harms health and is often called "bad cholesterol." Cholesterol attached to high-density lipoprotein (HDL) is good for health and is often called "good cholesterol."