What is cholesterol?

The liver makes most of the cholesterol the body needs, and the rest comes from animal foods such as meat, eggs and dairy. Cholesterol travels in the blood inside particles called lipoproteins. Low-density lipoprotein, or LDL, is often called bad cholesterol because high levels can build up as plaque in artery walls, raising the risk of heart attacks and strokes. High-density lipoprotein, or HDL, is called good cholesterol because it helps carry excess cholesterol back to the liver. Diet, exercise, genetics and medicines such as statins all influence blood cholesterol levels.