Cholesterol is a substance which is produced by the liver. A smaller proportion is absorbed from food. The body uses cholesterol primarily for forming cell membranes, producing bile and to protect the skin. Cholesterol travels though the bloodstream in small packages called lipoproteins. The most important lipoproteins are LDL (low-density lipoprotein) and HDL (high-density lipoprotein). While HDL has preventative effects on vascular diseases, LDL is accused of being responsible for the development of circulatory disorders.