Cholesterol, basic component of fats or lipids, a steroid found in nearly all tissues. Cholesterol is present in large quantity in the nervous system, where it is a compound of myelin, the greasy substance that acts as a sheath around nerve fibers. It is a precursor of bile salts and of adrenal and sex hormones. Large amounts are synthesized in the liver, intestines, and skin. Since abnormal depositing of cholesterol in the arteries is associated with aterio-arteriosclerosis, some doctors advise avoiding high-cholesterol foods and substituting unsaturated for saturated fats. Cholesterol is also a major constituent of gallstones.
See also: Arteriosclerosis.