Cholesterol is an essential fat made by the liver. Many people get additional cholesterol by eating meat and dairy products. Too much dietary intake may raise blood cholesterol levels, and lead to heart disease. Cholesterol is transported through the bloodstream by lipoproteins.

HDLs (high-density lipoproteins) are called "good" because they move cholesterol away from artery walls and back to the liver.

LDLs (low-density lipoproteins) are called "bad" because they keep cholesterol circulating in the blood, causing the arteries to become clogged with deposits.