Some is cholesterol. Cholesterol is synthesized in many tissues in the body, but the majority of cholesterol synthesis occurs in the liver. Cholesterol is the precursor of all steroids in the body such as corticosteroids, sex hormones, and bile acids. However, it should be noted that the amount synthesized and metabolized daily by the body itself is far greater than the amount usually consumed in the diet. Only about 40 per cent of cholesterol that is in food, is absorbed.
Cholesterol travels through the bloodstream to the body's cells.
Because cholesterol and other fats cannot dissolve in the blood, they must travel to and from the cells via special carriers called lipoproteins. LDL is the major cholesterol carrier in the blood. The liver uses some LDL and some is used by the tissues to form cell membranes. The problem occurs when one has an abundance of LDL in the blood. This condition is called atherosclerosis.