Cholesterol in the body comes from diet, but is also produced by the liver. This is the major constituent of bile and it is involved in the formation of certain hormones. Cholesterol levels must be balanced to prevent atherosclerosis, or gallstones. It is composed of HDL and LDL cholesterol: LDL cholesterol, also called bad cholesterol, is responsible for atherogenesis, cholesterol deposits on the walls of blood vessels which increase the risk of cardiovascular disease; on the other hand, HDL cholesterol, commonly called good, protects against these risks. A healthy diet is recommended to reduce the level of bad cholesterol in the blood.