Cholesterol is a waxy substance that occurs naturally in all parts of the body and is necessary for the body to function normally. The body uses cholesterol to produce many hormones, vitamin D, and bile acids that help digest fat. Only a small amount of cholesterol is needed to meet these needs. Excess cholesterol in the bloodstream can be harmful and lead to atherosclerosis, a condition in which fat and cholesterol are deposited in the walls of the arteries, including the coronary arteries feeding the heart. In time, the arteries narrow and symptoms of CHD appear, including angina and heart attacks.
Cholesterol travels in the blood in packages called lipoproteins.
HDLs help cholesterol from building up in the arterial walls. The higher your HDL-cholesterol the better. Triglycerides are a form of fat carried in the bloodstream. Most of your body's fat in the form of triglycerides is stored in fat tissue. Only a small segment of triglycerides is in the bloodstream.