What is cholesterol?
Biologically, cholesterol is one of the most important representatives of sterols - organic substances belonging to the group of steroids of natural biologically active substances. As it was said earlier, it takes a direct part in the metabolism.
However, cholesterol also has a number of negative properties. So its high content can lead to the development of atherosclerosis. An elevated level of its content in the blood can be observed in diabetes mellitus, gout, hypertension, hypothyroidism, obesity, acute disturbance of cerebral circulation, liver diseases and other diseases. There may also be a decrease in cholesterol, for example, with the following diseases: acute and chronic bowel diseases, severe heart failure with stagnant blood in the liver, a number of infectious diseases, hyperthyroidism.
Cholesterol does not dissolve in water, but can dissolve in substances such as alcohol, esters, acetone, other organic solvents, as well as in plant and animal fats. The main biological significance of cholesterol in its ability to form esters when reacting with fatty acids. With such a reaction, the appearance of an intensely colored compound is observed-this property and is used in obtaining a blood test for cholesterol.
Cholesterol functions
Cholesterol has a number of physiological functions - it forms bile acids in the human body, sex and corticosteroid hormones, vitamin D3.
It is contained in every cell of the human body, supporting their form. Being in the composition of cell membranes, it ensures their selective permeability for all substances that enter the cell and exit it. He also participates in the process of regulating the activity of cell enzymes.
The process of decomposition and elimination of toxins from the body also takes place with the participation of cholesterol. Turning into bile acids, it is part of the bile and takes an active part in the process of digesting food. Liver diseases contribute to the disruption of the formation and release of cholesterol, which leads to its retention in the blood and deposition in the form of atherosclerotic plaques in the blood vessels.
During the day about 500 mg of cholesterol in the human body is oxidized to bile acids, approximately the same amount is released with feces, with skin fat - about 100 mg.
"Useful" and "harmful" cholesterol
Cholesterol is a part of protein-fatty complexes (lipoprotein) plasma of human and animal blood. Thanks to these complexes it is transferred to tissues and organs. So-called lipoprotein complexes of low density (LDL) in the adult body contain about 70% of cholesterol, about 9-10% of it is part of very low density lipoproteins (VLDL), and about 20-24% of cholesterol contain high density lipoproteins (HDL) . It is LDL that promotes the formation of atherosclerotic plaques that cause atherosclerosis. It is in the composition of LDL and is "harmful" cholesterol.
But HDL has an anti-atherosclerotic effect. Studies have shown that it is his presence in the blood of some animals that makes them not prone to developing atherosclerosis. Thus, HDL contains "useful" cholesterol, which is transferred to them for catabolism in the liver.
Previously, it was believed that all cholesterol is the cause of atherosclerosis, so doctors recommended reducing the use of foods with its high content. Today it is already known that the reason for the development of atherosclerosis is precisely the animal fats that are the source of LDL, and which are rich in saturated fatty acids. Atherosclerosis also causes carbohydrates, which are easily absorbed by the body, which are in large quantities in sweets, buns. But the presence of vegetable fats in the human diet, which is the source of HDL, that is, "useful" cholesterol, is very important, because it is the prevention of atherosclerosis.
The norm of the content of cholesterol in the blood
As for any substance contained in the blood, cholesterol has its own norms for its content, while for men the indices are higher. So the total cholesterol should be at the level of 3.0-6.0 mmol / L, the normal level of "bad" cholesterol (LDL) is 1.92-4.82 mmol / l and the "useful" (HDL) - 0.7- 2.28 mmol / l.