Cholesterol

Cholesterol is a monohydric alcohol that can be considered the main representative of sterols. Cholesterol is a colourless, odourless and tasteless, fat-like substance that is insoluble in water but readily soluble in hot ethanol, ether and fatty oils.

70% of the cholesterol transported in the blood in lipoproteins is present as cholesterol ester. These can be broken down more easily in the liver. The lecithin-cholesterol acyltransferase (LCAT) catalyses the formation of cholesterol esters from cholesterol and lecithin. Mutations in the LCAT gene are the cause of a familial HDL deficiency and the so-called fish-eye disease.

The peripheral cell covers its cholesterol requirement preferably by absorbing LDL from plasma. Only in case of insufficient supply the cell's own cholesterol synthesis is increased. LDL are mainly transported through the cell wall via LDL receptors. HDL is necessary for the return transport of cholesterol from peripheral tissues to the liver. This so-called reverse cholesterol transport is the most important task of HDL. The cholesterol transported to the liver with HDL is also used for the synthesis of bile acid.

Cholesterol is also excreted through the skin, partly in metabolized form as squalene.

Cholesterol in plasma and serum (standard value):

• Total (in plasma and serum): up to 200 mg/dl, < 5.2 mmol/l.
• VLDL (very low density lipoproteins): 20mg/dl
• LDL (in plasma and serum): Ia: < 160 mg/l, Ib: 130 mg/l; II: <100 mg/l
• HDL (in plasma and serum): > 40 mg/dl

Cholesterol in cosmetics: Cholesterol is used in cosmetic products. Cholesterol makes the skin smooth and supple. The substance also acts as an emulsifier. Cholsterol stabilizes the consistency and shelf life of formulations.