For a long time now, the whole world has been actively fighting cholesterol, or rather, its high content in the human body and the consequences of this. Scientists from different countries put forward their opinions and evidence on this matter, argue about their correctness and give arguments. To understand the benefits and harms of this substance for human life, it is necessary to find out the biological role of cholesterol. You will learn about the features, properties, causes of high cholesterol, as well as tips for controlling its content in the blood from this article.
The structure of cholesterol, its biological role
Cholesterol literally means "hard bile" in ancient Greek. It is an organic compound that is involved in the formation of cells of all living organisms, except for plants, fungi and prokaryotes (cells that do not have a nucleus).
The biological role of cholesterol is difficult to overestimate. In the human body, it performs a number of significant functions, the violation of which leads to pathologicalhe alth changes.
Functions of cholesterol:
- Participates in the structure of cell membranes, giving them firmness and elasticity.
- Provides selective tissue permeability.
- Participates in the synthesis of hormones such as estrogens and corticoids.
- Affects the production of vitamin D and bile acids.
The peculiarity of cholesterol is that it is insoluble in water in its pure form. Therefore, for its transportation through the circulatory system, special "transport" compounds are used - lipoproteins.
Synthesis and receiving from outside
Along with triglycerides and phospholipids, cholesterol is one of the three main types of fat in the body. It is a natural lipophilic alcohol. About 50% of cholesterol is synthesized daily in the human liver, 30% of its formation occurs in the intestines and kidneys, the remaining 20% comes from outside - with food. The production of this substance occurs as a result of a long complex process in which six stages can be distinguished:
- Production of mevalonate. The basis of this reaction is the breakdown of glucose to two molecules, after which they react with the substance acetoacetyltransferase. The result of the first stage is the formation of mevolanate.
- Isopentenyl diphosphate is obtained by adding three phosphate residues to the result of the previous reaction. This is followed by decarboxylation and dehydration.
- When three molecules of isopentenyl diphosphate combine, farnesyl diphosphate is formed.
- After combining tworesidues of farnesyl diphosphate, squalene is synthesized.
- Lanosterol is formed as a result of a complex process involving linear squalene.
- At the final stage, cholesterol is synthesized.
Confirms the important biological role of cholesterol biochemistry. This process is clearly regulated by the human body in order to prevent an overabundance or deficiency of this important substance. The liver enzyme system is able to speed up or slow down the lipid metabolism reactions that underlie the synthesis of fatty acids, phospholipids, cholesterol, etc. Speaking about the biological role, function and metabolism of cholesterol, it is worth noting that about twenty percent of its total amount enters the body with food. It is found in large quantities in animal products. The leaders are egg yolk, smoked sausages, butter and ghee, goose liver, liver pate, kidneys. By limiting your intake of these foods, you can reduce your intake of cholesterol.
The chemical structure of this organic compound as a result of metabolism cannot be split into CO2 and water. In this regard, most of the cholesterol is excreted from the body in the form of bile acids, the rest - with feces and unchanged.
"Good" and "bad" cholesterol
This substance is found in most tissues and cells of the human body, due to the biological role of cholesterol. It acts as a modifier of the bilayer of cells, giving it rigidity,which stabilizes the fluidity of the plasma membrane. After synthesis in the liver, cholesterol must be delivered to the cells of the whole body. Its transportation occurs as part of highly soluble complex compounds called lipoproteins.
They come in three types:
- High density lipoproteins (high molecular weight).
- Low density lipoproteins (low molecular weight).
- Very low density lipoproteins (very low molecular weight).
- Chylomicrons.
These compounds are distinguished by their tendency to precipitate cholesterol. A relationship was established between the content of lipoproteins in the blood and human he alth. People who had high levels of LDL had atherosclerotic changes in the vessels. Conversely, for those who had HDL in their blood, a he althy body was characteristic. The thing is that low molecular weight transporters are prone to precipitation of cholesterol, which settles on the walls of blood vessels. That's why it's called "bad". On the other hand, high-molecular compounds, having high solubility, are not atherogenic, therefore they are called "good".
Content in the blood. Norm indicators
Given the important biological role of cholesterol, its blood level should be within acceptable limits:
- in women, this rate varies from 1.92 to 4.51 mmol/L.
- for men - from 2.25 to 4.82 mmol/l.
In this case, the level of LDL cholesterol should be less than 3-3, 35 mmol / l, HDL- more than 1 mmol / l, triglycerides - 1 mmol / l. It is considered a good indicator if the amount of high-density lipoprotein is 20% of the total cholesterol. Deviations, both up and down, indicate he alth problems and require additional examination.
Reasons for high blood cholesterol
The increase in the content of "bad" cholesterol in the blood is called hypercholesterolemia. It increases the risk of cardiovascular disease. Speaking about the reasons for the increase in the amount of cholesterol in the blood, there are several:
- genetic changes of a hereditary nature;
- violation of the functions and activity of the liver - the main producer of lipophilic alcohol;
- hormonal changes;
- frequent stress;
- malnutrition (eating fatty foods of animal origin);
- metabolic disorders (pathology of the digestive system);
- smoking;
- sedentary lifestyle.
Danger of excess cholesterol in the body
Hypercholesterolemia contributes to the development of atherosclerosis (the formation of sclerotic plaques on the walls of blood vessels), coronary heart disease, diabetes, and the formation of gallstones. Thus, the important biological role and danger of changes in blood cholesterol levels are reflected in pathological changes in human he alth.
Control
To avoid the unpleasant consequences of high levels of "bad" cholesterol, it is necessary to prevent the growth of LDL and VLDL.
Everyone can do it, you need:
- reduce trans fat intake;
- increase the amount of fruits and vegetables in the diet;
- increase physical activity;
- no smoking;
If these rules are observed, the risk of high blood cholesterol is reduced several times.
Ways to decline
Conclusions about the level of cholesterol in the blood and the need to reduce it are made by medical specialists based on the results of the tests. Self-medication in this case can be dangerous.
With persistently high cholesterol, mainly conservative methods are used to reduce it:
- Use of medications (statins).
- Maintain a he althy lifestyle (proper nutrition, diet, physical activity, smoking cessation, quality and regular rest).
It is worth noting in conclusion: the structure and biological role of cholesterol, hypercholesterolemia and its consequences confirm the importance of this substance and all the processes associated with it for a person. Therefore, it is necessary to take a responsible attitude to factors that can affect the quality and quantity of cholesterol in the body.
