What is cholesterol and lipoproteins
Cholesterol is synthesized mainly in the liver, and also enters the body with food. With full nutrition in the human body, about 500 mg of cholesterol per day comes from food, and approximately the same amount is formed in the body itself (50% in the liver, 15% in the intestine, the rest in the skin).
Cholesterol molecules from food are absorbed into the intestines and enter the bloodstream. To tissues it is transferred in the structure of special protein-lipid complexes – lipoproteins. They include proteins – apoproteins, cholesterol, as well as other lipid substances – triglycerides. The more in the composition of such a complex of cholesterol, the lower its density. This feature distinguishes low density lipoprotein (LDL), very low density (VLDL) and high density (HDL).
VLDL are synthesized in the liver. Of these, LDL is formed. The latter are most rich in cholesterol. They can contain up to 2/3 of the total cholesterol of the blood plasma. LDL play a major role in the transport of cholesterol to the vascular wall and in the formation of atherosclerosis.
It is known that the higher the body’s need for building material for the formation of new cell membranes, the greater the need for steroid hormones, the lower the LDL in the blood and the less likely the formation of atherosclerotic plaques in the vessels.
HDL is synthesized in the liver. They contain less cholesterol compared to LDL. These lipoproteins carry back the transport of cholesterol from vessels, organs and tissues, transferring it to other lipoproteins or transporting directly to the liver, followed by removal from the body with bile. The higher the level of HDL in the blood and the greater the proportion of cholesterol contained in them, the less likely the development of atherosclerosis and the greater the possibility of reverse development of atherosclerotic plaques.
In the human body, about 70% of cholesterol is contained in LDL, 10% in VLDL and 20% in HDL.