For a long time now, the whole world has been actively fighting with cholesterol, and more precisely, with its increased content in the human body and the consequences of this. Scientists from different countries put forward their opinions and evidence on this subject, argue about their innocence and give arguments. To understand the benefits and dangers 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 cholesterol increase, as well as tips for controlling its blood level from this article.
The structure of cholesterol, its biological role
Translated from ancient Greek cholesterol literally means "hard bile." 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 pathological changes in health.
Cholesterol Functions:
- Participates in the structure of cell membranes, giving them firmness and elasticity.
- Provides selective tissue permeability .
- It takes part 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 in its pure form it is insoluble in water. Therefore, for its transportation through the circulatory system, special "transport" compounds are used - lipoproteins.
Synthesis and external reception
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:
- The production of mevalonate. This reaction is based on the breakdown of glucose into two molecules, after which they react with the substance acetoacetyltransferase. The result of the first stage is the formation of mevolanate.
- Obtaining isopentenyl diphosphate is carried out by adding three phosphate residues to the result of the previous reaction. Then decarboxylation and dehydration take place.
- When three isopentenyl diphosphate molecules are combined, farnesyl diphosphate is formed.
- After combining the two residues of farnesyl diphosphate, squalene is synthesized.
- As a result of a complex process involving linear squalene, lanosterol is formed.
- At the final stage, cholesterol synthesis occurs.
Biochemistry confirms the important biological role of cholesterol. 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 accelerate 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 is ingested with food. It is found in large quantities in animal products. The leaders are egg yolk, smoked sausages, butter and ghee, goose liver, liver paste, kidneys. By limiting your intake of these foods, you can lower your cholesterol from the outside.
The chemical structure of this organic compound as a result of metabolism cannot be split into CO 2 and water. In this regard, most of the cholesterol is excreted 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, thereby stabilizing 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 well-soluble complex compounds called lipoproteins.
They are of 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 characterized by a tendency to precipitate cholesterol. A relationship has been established between blood lipoproteins and human health. People who had high LDL levels had atherosclerotic changes in their vessels. Conversely, for those with HDL predominant in their blood, a healthy 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. Therefore, it is called "bad." On the other hand, high molecular weight compounds, having great solubility, are not atherogenic, therefore they are called "good."
The content in the blood. Rate Level Indicators
Given the important biological role of cholesterol, its level in the blood should be within acceptable values:
- in women, this norm varies from 1.92 to 4.51 mmol / L.
- in 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 lipoproteins is 20% of the total cholesterol. Deviations, both up and down, indicate health problems and require additional examination.
Causes of an increase in blood cholesterol
Increasing the content of "bad" cholesterol in the blood is called hypercholesterolemia. It increases the risk of heart disease. Speaking about the reasons for the increase in the amount of cholesterol in the blood, several can be distinguished:
- 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 disturbance (pathology of the digestive system);
- smoking;
- sedentary lifestyle.
The 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 health.
Control
To avoid the unpleasant consequences of increasing the level of "bad" cholesterol, it is necessary to prevent the growth of LDL and VLDL.
Everyone can do this, it is necessary:
- reduce trans fat intake;
- increase the amount of fruits and vegetables in the diet;
- increase physical activity;
- exclude smoking;
Subject to these rules, the risk of an increase in blood cholesterol is reduced several times.
Ways to reduce
Conclusions about the level of cholesterol in the blood and the need to lower it are made by medical specialists based on the results of the analyzes. Self-medication in this case can be dangerous.
With stably elevated cholesterol, mainly conservative methods are used to reduce it:
- The use of medications (statins).
- Compliance with a healthy 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 for humans of this substance and all the processes associated with it. Therefore, you must be responsible for the factors that can affect the quality and quantity of cholesterol in the body.