Cholesterol is a fatty substance in the blood. There are two types of cholesterol. A correct balance between the two is needed for good health.High-density lipoprotein (HDL) or “good” cholesterol helps remove excess cholesterol from the body. Low-density lipoprotein (LDL) or “bad” cholesterol can cause cholesterol to build up in the arteries. Low HDL or high LDL cholesterol increases the risk of coronary heart disease. LDL cholesterol forms a substance called plaque in the arteries of the heart.