Interesting facts about lipids. Lipids - what are they? Lipids: functions, characteristics. Disruption of the normal concentration of lipids in the blood

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Lipids in nutrition

Along with proteins and carbohydrates, lipids are the main food elements that make up a significant part of food. The intake of lipids in the body with food has a significant effect on human health in general. Insufficient or excessive consumption of these substances can lead to the development of various pathologies.

Most people eat quite variedly, and all the necessary lipids enter their body. It should be noted that some of these substances are synthesized by the liver, which partly compensates for their lack in food. However, there are also irreplaceable lipids, or rather their components - polyunsaturated fatty acids. If they do not enter the body with food, over time this will inevitably lead to certain disorders.

Most of the lipids in food are used by the body for energy production. That is why, during fasting, a person loses weight and weakens. Deprived of energy, the body begins to consume lipid stores from the subcutaneous fatty tissue.

Thus, lipids play a very important role in healthy human nutrition. However, for some diseases or disorders, their number should be strictly limited. Patients usually learn about this from the attending physician ( usually a gastroenterologist or nutritionist).

Energy value of lipids and their role in diet

The energy value of any food is calculated in calories. A food product can be decomposed according to its composition into proteins, carbohydrates and lipids, which together make up the bulk. Each of these substances in the body breaks down with the release of a certain amount of energy. Proteins and carbohydrates are absorbed more easily, but with the breakdown of 1 g of these substances, about 4 Kcal are released ( kilocalories) energy. Fats are more difficult to digest, but when 1 g breaks down, about 9 Kcal is released. Thus, the energy value of lipids is the highest.

In terms of energy release, triglycerides play the most important role. The saturated acids that make up these substances are absorbed by the body by 30 - 40%. Monounsaturated and polyunsaturated fatty acids are completely absorbed by a healthy body. Adequate intake of lipids allows carbohydrates and proteins to be used for other purposes.

Plant and animal lipids

All lipids that enter the body with food can be divided into substances of animal and plant origin. From a chemical point of view, the lipids that make up these two groups differ in their composition and structure. This is due to differences in the functioning of cells in plants and animals.

Examples of vegetable and animal lipid sources

Each lipid source has specific advantages and disadvantages. For example, animal fats contain cholesterol, which is not found in plant foods. In addition, animal products contain more lipids and are more energy-efficient to consume. At the same time, an excess of animal fats increases the risk of developing a number of diseases associated with lipid metabolism in the body ( atherosclerosis, cholelithiasis, etc.). There are fewer lipids in plant foods, but the body cannot synthesize them on its own. Even a small amount of seafood, citrus fruits or nuts provides enough polyunsaturated fatty acids that are vital for humans. At the same time, a small proportion of lipids in plants cannot fully cover the body's energy costs. That is why, in order to maintain health, it is recommended to make the diet as varied as possible.

What is the body's daily requirement for lipids?

Lipids are the main suppliers of energy to the body, but their excess can harm health. First of all, this concerns saturated fatty acids, most of which are deposited in the body and often leads to obesity. The optimal solution is to maintain the necessary proportions between proteins, fats and carbohydrates. The body should receive as many calories as it spends during the day. That is why the rates of lipid intake can be different.

The following factors can affect the body's need for lipids:

Body weight. Overweight people have to expend more energy. If they are not going to lose weight, then the need for calories and, accordingly, for lipids will be slightly higher. If they seek to lose weight, then first of all, it is necessary to limit fatty foods.
Loads throughout the day. People who do hard physical work or athletes need a lot of energy. If the average person has 1,500 - 2,500 calories, then the miners or loaders may have a rate of up to 4,500 - 5,000 calories per day. Of course, the need for lipids also increases.
The nature of the diet. Every country and every nation has its own traditions in nutrition. When calculating the optimal diet, one must take into account what kind of foods a person usually consumes. For some peoples, fatty foods are a kind of tradition, while others, on the contrary, are vegetarians, and their lipid consumption is minimized.
The presence of concomitant pathologies. For a number of disorders, lipid intake should be limited. First of all, we are talking about diseases of the liver and gallbladder, since it is these organs that are responsible for the digestion and assimilation of lipids.
The age of the person. In childhood, the metabolism is faster and the body requires more energy for normal growth and development. In addition, children usually do not have serious gastrointestinal problems, and they digest any food well. It should also be borne in mind that infants receive an optimal set of lipids in breast milk. Thus, age strongly influences the rate of fat intake.
Floor. It is believed that, on average, a man consumes more energy than a woman, therefore, the rate of fat in the diet of men is slightly higher. However, in pregnant women, the need for lipids increases.

It is believed that a healthy adult male who works 7 to 8 hours a day and maintains an active lifestyle should consume about 2,500 calories per day. Fats provide about 25 - 30% of this energy, which corresponds to 70 - 80 g of lipids. Of these, saturated fatty acids should be about 20%, and polyunsaturated and monounsaturated ones - about 40%. It is also recommended to give preference to lipids of plant origin ( about 60% of the total).

It is difficult for a person to independently make the necessary calculations and take into account all the factors for selecting an optimal diet. To do this, it is best to see a dietitian or food hygiene specialist. After a short survey and clarification of the nature of the diet, they will be able to draw up the optimal daily diet, which the patient will adhere to in the future. They can also advise on specific foods that contain the required lipids.

What foods mainly contain lipids ( milk, meat, etc.)?

In one or another amount, lipids are found in almost all food products. However, in general, animal products are richer in these substances. In plants, the mass fraction of lipids is minimal, but the fatty acids included in such lipids are the most important for the body.

The amount of lipids in a particular product is usually indicated on the packaging of the product in the "nutritional value" section. Most manufacturers are required to inform consumers about the mass fraction of proteins, carbohydrates and fats. In self-prepared food, the amount of lipids can be calculated using special tables for nutritionists, which indicate all the main foods and dishes.

Mass fraction of lipids in staple foods

Most plant foods ( vegetables, fruits, herbs, roots) the mass fraction of fats is not more than 1 - 2%. The exceptions are citrus fruits, where the proportion of lipids is slightly higher, and vegetable oils, which are lipid concentrates.

Are there essential lipids, and what are their most important sources?

Fatty acids are the structural unit of lipids. Most of these acids can be synthesized by the body ( mainly by liver cells) from other substances. However, there are a number of fatty acids that the body cannot produce on its own. Thus, lipids containing these acids are essential.

Most of the essential lipids are found in plant foods. These are monounsaturated and polyunsaturated fatty acids. The cells of the body cannot synthesize these compounds, since the metabolism in animals is very different from that in plants.

Essential fatty acids and their main dietary sources

For a long time, the above fatty acids were equated in importance for the body with vitamins. Adequate consumption of these substances strengthens the immune system, accelerates cell regeneration, reduces inflammation, and promotes the conduction of nerve impulses.

What does the lack or excess of lipids in the diet lead to?

Both a lack and an excess of lipids in the diet can seriously affect the health of the body. In this case, we are not talking about a one-time intake of a large amount of fat ( although this can have certain consequences), but about the systematic abuse of fatty foods or prolonged fasting. At first, the body is quite capable of successfully adapting to a new diet. For example, with a lack of lipids in food, the most important substances for the body will still be synthesized by its own cells, and energy needs will be covered by the breakdown of fat reserves. With an excess of lipids in the diet, a significant part will not be absorbed in the intestine and will leave the body with fecal masses, and some of the lipids that enter the blood are transformed into adipose tissue. However, these adaptation mechanisms are temporary. Plus, they only work well in a healthy body.

Potential Effects of Diet Lipid Imbalances

Blood and plasma lipids

A significant proportion of lipids are present in the blood in various forms. Most often these are compounds of lipids with other chemicals. For example, triglycerides and cholesterol are transported mainly as lipoproteins. The levels of various lipids in the blood can be determined using biochemical blood tests. This allows you to identify a number of violations and suspect the corresponding pathology.

Triglycerides

Triglycerides perform mainly an energy function. They enter the body with food, are absorbed in the intestines and are carried throughout the body with the blood in the form of various compounds. The normal content is considered to be a level of 0.41 - 1.8 mmol / l, but it can fluctuate within significant limits. For example, after consuming a large amount of fatty foods, the level of triglycerides in the blood can increase 2 to 3 times.

Free fatty acids

Free fatty acids enter the bloodstream as a result of the breakdown of triglycerides. Normally, they are deposited in adipose tissue. Modern research has shown the relationship between the level of free fatty acids in the blood and some pathological processes. For example, in people with a high concentration of fatty acids ( fasting) insulin is produced worse, so the risk of developing diabetes is higher. The normal content of fatty acids in the blood of an adult is 0.28 - 0.89 mmol / l. In children, the boundaries of the norm are wider ( up to 1.10 mmol / l).

Cholesterol

Cholesterol is one of the most important lipids in the human body. It is part of many cellular components and other substances, influencing a variety of processes. An excess or deficiency of this substance or a violation of its absorption by the body can lead to the development of serious diseases.

In the human body, cholesterol performs the following functions:

stiffens cell membranes;
takes part in the synthesis of steroid hormones;
is part of bile;
participates in the assimilation of vitamin D;
regulates the permeability of the walls of some cells.

Lipoproteins ( lipoproteins) and their fractions ( low density, high density, etc.)

The term lipoproteins or lipoproteins denote a group of complex protein compounds that transport lipids in the blood. Some lipoproteins are fixed in cell membranes and perform a number of functions related to cell metabolism.

All blood lipoproteins are divided into several classes, each of which has its own characteristics. The main criterion by which lipoproteins are distinguished is their density. According to this indicator, all these substances are divided into 5 groups.

There are the following classes ( factions) lipoproteins:

High density. HDL) take part in the transfer of lipids from body tissues to the liver. From a medical point of view, they are considered useful, since, due to their small size, they can pass through the walls of blood vessels and "clean" them from lipid deposits. Thus, high HDL levels reduce the risk of atherosclerosis.
Low density. LDL) carry out the transport of cholesterol and other lipids from the liver ( places of their synthesis) to the tissues. From a medical point of view, this fraction of lipoproteins is harmful, since it is LDL that contributes to the deposition of lipids on the walls of blood vessels with the formation of atherosclerotic plaques. High LDL cholesterol levels greatly increase the risk of atherosclerosis.
Average ( intermediate) density. Intermediate density lipoproteins ( LDPP) do not have significant diagnostic value, since they are an intermediate product of lipid metabolism in the liver. They also carry lipids from the liver to other tissues.
Very low density. VLDL) transfer lipids from the liver to the tissues. They also increase the risk of developing atherosclerosis, but in this process they play a secondary role ( after LDL).
Chylomicrons. Chylomicrons are significantly larger than other lipoproteins. They are formed in the walls of the small intestine and carry lipids from food to other organs and tissues. In the development of various pathological processes, these substances do not play a significant role.

Currently, the biological role and diagnostic value of most lipoproteins has been disclosed, but there are still some questions. For example, the mechanisms that increase or decrease the level of a particular lipoprotein fraction are not fully understood.

Lipid analysis

Currently, there are many laboratory tests with which you can determine the various lipids in the blood. Usually, venous blood is taken for this. The patient is sent for analysis by the attending physician. The most important lipids ( total cholesterol, triglycerides) is determined in a biochemical blood test. If the patient needs a more detailed examination, the doctor indicates which lipids need to be determined. The analysis itself usually takes several hours. Most laboratories issue results the next day.

What is a lipid profile?

Lipidogram is a complex of laboratory blood tests aimed at finding out the level of lipids in the blood. This is the most useful study for patients with various disorders of lipid metabolism, as well as for patients with atherosclerosis. Some indicators included in the lipid profile are also determined in a biochemical blood test, but in some cases this may not be enough for an accurate diagnosis. A lipidogram is prescribed by the attending physician based on the patient's symptoms and complaints. This analysis is carried out by almost any biochemical laboratory.

Lipidogram includes tests to determine the following blood lipids:

Cholesterol. This indicator does not always depend on lifestyle and nutrition. A significant part of the cholesterol in the blood is the so-called endogenous cholesterol, which is produced by the body itself.
Triglycerides. Triglyceride levels usually rise or fall in proportion to cholesterol levels. It can also increase after eating.
Low density lipoproteins ( LDL). The accumulation of these compounds in the blood greatly increases the risk of developing atherosclerosis.
High density lipoproteins ( HDL). These compounds are able to "cleanse" the blood vessels from excess cholesterol and are beneficial for the body. Low HDL levels indicate that the body does not absorb fat well.
Very low density lipoproteins ( VLDL). They are of secondary diagnostic value, but their increase along with an increase in LDL levels usually indicates atherosclerosis.

If necessary, other indicators can be added to the lipid profile. Based on the results, the laboratory can issue, for example, an atherogenic coefficient, which reflects the risk of developing atherosclerosis.

Before donating blood for a lipid profile, you should adhere to a few simple rules. They will help to avoid significant fluctuations in blood lipid levels and make the results more reliable.

Before taking the analysis, patients should take into account the following recommendations:

In the evening before taking the test, you can eat, but you should not abuse fatty foods. It is better to stick to your usual diet.
The day before taking the analysis, it is necessary to exclude various kinds of loads ( both physical and emotional), as they can lead to the breakdown of fatty tissue in the body and an increase in blood lipids.
Do not smoke in the morning just before donating blood.
Regular intake of a number of drugs also affects the level of lipids in the blood ( contraceptive drugs, hormonal drugs, etc.). It is not necessary to cancel them, but this fact should be taken into account when interpreting the results.

Based on the lipid profile, doctors can make the correct diagnosis and prescribe the necessary treatment.

Normal blood lipids

The boundaries of the norm are somewhat different for all people. It depends on gender, age, the presence of chronic pathologies and a number of other indicators. However, there are certain limits, exceeding which clearly indicates the existence of problems. The table below shows the generally accepted normal limits for various blood lipids.
The boundaries of the norm are relative, and the patient himself cannot always draw the correct conclusions when interpreting the results of the analysis. The attending physician, when familiarizing himself with the results, must take into account that during pregnancy the boundaries of the norm expand, as in fasting. Therefore, you should not panic with some deviations from the norm. The final conclusion in any case must be made by the attending physician.

Diseases associated with lipid metabolism

There are quite a few diseases that, to one degree or another, are associated with lipid metabolism in the body. Some of these pathologies cause an increase or decrease in various lipids in the blood, which is reflected in the analyzes. Other pathologies are the result of lipid imbalances.

Lipid metabolic disorders ( dyslipidemia)

Excess or deficiency of lipids in the diet can lead to a variety of pathologies. In a healthy body that normally assimilates all incoming substances, this imbalance does not so much affect metabolic processes. For example, excess lipids do not always lead to obesity. For this, a person must also have a genetic predisposition, endocrine disorders, or he must lead a sedentary lifestyle. In other words, the amount of lipids in the diet in most cases is only one of many factors that influence the appearance of pathology.

Lipid imbalance can lead to the following pathologies:

atherosclerosis ( as a result - aneurysms, coronary heart disease, hypertension or other problems with the cardiovascular system);
skin problems;
problems with the nervous system;
a number of pathologies of the gastrointestinal tract ( pancreatitis, cholelithiasis, etc.).

Lack of lipids in the diet in young children can affect weight gain and developmental speed.

Causes of high and low lipid levels

The most common cause of elevated lipid levels in a blood test is donation errors. Patients don’t donate blood on an empty stomach, because of which the lipid content does not have time to normalize, and the doctor may mistakenly suspect some problems. However, there are many pathologies that cause abnormalities in blood lipids, regardless of nutrition.

Pathological conditions associated with a change in the amount of lipids in the blood are called dyslipidemias. They are also divided into several types. If the level of triglycerides in the blood is elevated, they talk about hypertriglyceridemia ( synonym - hyperlipemia). If the level of cholesterol rises, they talk about hypercholesterolemia.

Also, all dyslipidemias by origin are divided into the following groups:

Primary. Primary dyslipidemias are generally understood to be genetic diseases and abnormalities. As a rule, they are manifested by an excess or deficiency of any enzymes, which disrupts lipid metabolism. As a result, the amount of these substances in the blood decreases or increases.
Secondary. Secondary dyslipidemias mean pathological conditions in which an increase in blood lipids is a consequence of some other pathology. Thus, it is necessary to treat, first of all, this particular pathology, then the lipid level will gradually stabilize.

The main task of the attending physician is the correct diagnosis, based on the test results and symptoms of the patient. Secondary dyslipidemias are more common and are usually ruled out first. Primary dyslipidemias are much less common, but they are much more difficult to diagnose and treat.

There are five main types of primary hyperlipoproteinemia ( elevated lipoprotein levels):

Hyperchylomicronemia. With this disease, the level of triglycerides in the blood rises, while the level of other lipids usually remains within the normal range. Patients may experience paroxysmal abdominal pain, but without tension in the abdominal muscles. Xanthomas ( formation of brown or yellowish color). The disease does not lead to the development of atherosclerosis.
Familial hyper-beta lipoproteinemia. With this pathology, the amount of beta-lipoproteins, and sometimes pre-beta-lipoproteins, increases. In the analysis, the level of cholesterol is significantly exceeded. The amount of triglycerides may be normal or slightly increased. Patients also develop xanthomatosis ( xanthomas on the skin). The risk of atherosclerosis is significantly increased. With this disease, myocardial infarction is possible even at a young age.
Familial hypercholesterolemia with hyperlipemia. In the blood, the level of both cholesterol and triglycerides is significantly increased. Xanthomas are large and appear after 20 to 25 years. The risk of developing atherosclerosis is increased.
Hyper-pre-beta lipoproteinemia. In this case, the triglyceride level rises, and the cholesterol level remains within the normal range. The disease is often associated with diabetes, gout, or obesity.

Essential hyperlipemia ( Burger-Grütz disease). The above diseases are diagnosed on the basis of electrophoresis data. One of these pathologies can be suspected as follows. In healthy people, after eating with an abundance of fatty foods, lipemia is observed ( mainly due to the level of chylomicrons and beta-lipoproteins), which disappears after 5 - 6 hours. If the level of triglycerides in the blood does not fall, tests should be done to detect primary hyperlipoproteinemia.

There are also secondary ( symptomatic) hyperlipoproteinemia in the following diseases:

Diabetes. In this case, the excess of lipids in the blood is explained by the transformation of excess carbohydrates.
Acute pancreatitis. With this disease, the absorption of lipids is impaired, and their level in the blood increases due to the breakdown of adipose tissue.
Hypothyroidism The disease is caused by a lack of thyroid hormones, which regulate, among other things, lipid metabolism in the body.
Intrahepatic cholestasis and other liver pathologies. The liver takes part in the synthesis of most of the lipids required by the body. With various hepatitis, violations of the outflow of bile and other pathologies of the liver and bile ducts, the level of lipids in the blood may increase.
Nephrotic syndrome. This syndrome develops with damage to the glomerular apparatus of the kidneys. Patients have severe renal edema. The level of proteins in the blood drops, and the level of cholesterol rises significantly.
Porphyria. Porphyria is a hereditary disorder. In patients, the metabolism of a number of substances is disturbed, as a result of which porphyrins accumulate in the blood. In parallel, lipid levels may increase ( sometimes significantly).
Certain autoimmune diseases. In autoimmune diseases, the antibodies produced by the body attack its own cells. In most cases, chronic inflammatory processes develop, with which an increase in lipid levels is associated.
Gout. With gout, the metabolism of uric acid is disrupted in the body, and it accumulates in the form of salts. This is partly reflected in lipid metabolism, although their level in this case is slightly increased.
Alcohol abuse. Alcohol abuse leads to liver and gastrointestinal tract pathologies. A number of enzymes can be activated that increase blood lipid levels.
Taking some medications. For example, prolonged use of oral contraceptives ( contraceptives). Most often, this side effect is mentioned in the instructions for the corresponding drug. Before taking the analysis, such drugs should not be taken, or you need to warn the receiving doctor about this so that he correctly interprets the results of the analysis.

In the vast majority of cases, the cause of persistently elevated blood lipids is one of the above problems. It should also be noted that elevated lipid levels can be observed for a fairly long time after serious injury or myocardial infarction.

Also, an increased level of lipoproteins in the blood can be observed during pregnancy. This increase is usually negligible. With an increase in lipid levels 2 to 3 times higher than normal, the likelihood of pregnancy should be considered in combination with other pathologies that cause an increase in lipid levels.

What diseases of the digestive system are associated with lipid metabolism?

A healthy digestive system is the key to good absorption of lipids and other nutrients. A significant imbalance of lipids in food over time can lead to the development of certain pathologies of the stomach. One of the most common problems in cardiology is atherosclerosis. This disease occurs due to the deposition of lipids in the vessels ( predominantly in the arteries). As a result of this process, the lumen of the vessel narrows and blood flow is impeded. Patients may experience different symptoms depending on which arteries are affected by atherosclerotic plaques. High blood pressure, coronary heart disease ( sometimes myocardial infarction), the appearance of aneurysms.

Atherogenic lipids are those substances that lead to the development of atherosclerosis. It should be noted that the division of lipids into atherogenic and non-atherogenic is rather arbitrary. In addition to the chemical nature of substances, many other factors contribute to the development of this disease.

Atherogenic lipids often lead to the development of atherosclerosis in the following cases:

heavy smoking;
heredity;
diabetes;
overweight ( obesity);
sedentary lifestyle ( lack of exercise) and etc.

In addition, when assessing the risk of atherosclerosis, it is not so much the substances consumed that are important ( triglycerides, cholesterol, etc.), but rather the process of assimilation of these lipids by the body. In the blood, a significant part of lipids is present in the form of lipoproteins - compounds of lipid and protein. Low-density lipoproteins are characterized by the "settling" of fats on the walls of blood vessels with the formation of plaques. High density lipoproteins are considered "antiatherogenic", as they help cleanse blood vessels. Thus, with the same diet, some people develop atherosclerosis, while others do not. Both triglycerides and saturated and unsaturated fatty acids can be transformed into atherosclerotic plaques. But it depends on the metabolism in the body. In general, however, it is believed that a significant excess of any lipids in the diet predisposes to the development of atherosclerosis. Before use, you must consult a specialist.

Fat has always been regarded as a harmful component of food for the body and some nutritionists are of the opinion that it is better to limit the intake of fat. But are fats so bad for us?

In reality, fats perform several very important functions for our body, and first of all, fat is an important supplier of energy for us. We can highlight the fact that 1 g of fat delivers more calories than proteins and carbohydrates in double the amount. The body does not burn all the fats at once, but stores some of it in the depot as a reserve in order to use it in the future as needed. We have provided you with information on fats that will help you look at fats in a new way.

Why is fat necessary for our body?

Fats supply fatty acids important for the life of our body, which are involved in metabolism and are energy suppliers. In addition, fats are part of the cell membranes, for example, nerve cells have membranes that are 60% fat. Thus, several important functions of fats can be distinguished:

Fats are the providers of energy material - approximately 30% of the energy comes from fats,

By forming subcutaneous fat, they protect organs and tissues from mechanical damage, and also prevent heat loss,

They are carriers for vitamins A, D, E, K, as well as for minerals, since their absorption in the body is impossible without fats,

They are part of the cell walls (mainly cholesterol). Without them, the cell loses its function and collapses,

Fats produce female sex hormones, which is especially important in postmenopausal women, when the function of the ovaries has practically died out. They also play an important role in the reproductive period, since they maintain the hormonal background at the proper level. If the level of adipose tissue in the body is below 10-15%, then hormonal imbalance occurs up to the termination of the menstrual cycle,

Omega-6 unsaturated acid (also known as arachidonic acid) is involved in the activation of the blood coagulation and anticoagulation systems.

Almost 35% of the daily diet should be fat. In this case, the type of fat plays a significant role.

Which fats are good and which are not?

Depending on the chemical structure, fats are divided into saturated and unsaturated fatty acids. Saturated fatty acids are high in hydrogen ions and are found in animal foods. These are exactly the fats that are deposited on the stomach, thighs, buttocks. This is a kind of energy reserve of the body. Saturated fat inhibits muscle growth by reducing the effects of insulin. But at the same time, they are the basis for the production of testosterone. If they are excluded from food, the level of this hormone, which is important for men, also decreases. The same can be obtained with excessive consumption. Therefore, they are also important for the body, but in moderation.

Unsaturated fatty acids (Omega-3 and Omega-6) contain few hydrogen ions and are found mainly in animal products, for example, olive oil, vegetable oil, fish oil. These fats are not stored in the body, but are completely burned. They are a useful component of nutrition for the body, raw materials for the production of hormones.

There are also so-called trans fats, or artificial fats. They are packed with hydrogen ions and are found in candy and biscuits, as well as fast food (fast food). They are used mainly for storing food and they increase the risk of developing cancer and diseases of the cardiovascular system.

Omega-3 and Omega-6 unsaturated fatty acids.

Of all types of fats, it is these fatty acids that are the most valuable for our body. They are found in sunflower and corn oils, and rapeseed oil contains them in an ideal ratio.

Omega-3 fatty acids that are beneficial to the body are also found in flaxseed, nut and soybean oils. Salmon, mackerel, and herring also contain plenty of them.

Omega-3 and Omega-6 fatty acids:

Reduces the risk of developing atherosclerosis, thus preventing the development of cardiovascular diseases

Reduce cholesterol levels,

Strengthen the walls of blood vessels,

Reduce blood viscosity, thus preventing the development of blood clots,

Improves the blood supply to organs and tissues, the restoration of nerve cells.

Ideally, you should mix saturated and unsaturated fats, for example, season meats and salads with rapeseed oil.

Which is better, margarine or butter?

In contrast to butter, margarine contains more unsaturated fatty acids. But according to new teachings, this does not mean that oil is more harmful. In terms of calories, both foods are almost equal. But margarine contains unhealthy trans fats that have been linked to a number of diseases.

If you are a fan of margarine, then go for the high quality, low solid fat varieties.

Does fat lead to obesity?

Despite the fact that fat contains more calories, there is no proven link between fat consumption and increased weight.

An excess of calories leads to obesity: those who consume more calories than they burn, gain weight. Foods that are high in fat will lead to long-term satiety and allow us to eat less.

On the contrary, who tries to save on fats, they often eat more carbohydrates. Grain foods such as white bread and pasta raise blood sugar, and with it insulin, which leads to an increase in adipose tissue. In addition, the saturation of the body occurs quickly, but not for a long time, as a result of which it leads to more frequent food consumption.

What are lipids, what is the classification of lipids, what is their structure and function? The answer to this and many other questions is provided by biochemistry, which studies these and other substances that are of great importance for metabolism.

What it is

Lipids are organic substances that do not dissolve in water. The functions of lipids in the human body are diverse.

Lipids - this word means "small particles of fat"

This is primarily:

Energy. Lipids serve as a substrate for storing and using energy. The breakdown of 1 gram of fat releases about 2 times more energy than the breakdown of protein or carbohydrates of the same weight.
Structural function. The structure of lipids determines the structure of the cell membranes in our body. They are arranged in such a way that the hydrophilic part of the molecule is inside the cell, and the hydrophobic part is on its surface. Due to these properties of lipids, each cell, on the one hand, is an autonomous system, fenced off from the outside world, and on the other hand, each cell can exchange molecules with others and with the environment using special transport systems.
Protective. The surface layer that we have on the skin and serves as a kind of barrier between us and the outside world is also composed of lipids. In addition, they, in the composition of adipose tissue, provide the function of thermal insulation and protection from harmful external influences.
Regulatory. They are part of vitamins, hormones and other substances that regulate many processes in the body.

The general characteristics of lipids are based on structural features. They have twofold properties, since they have soluble and insoluble parts in the molecule.

Intake of the body

Lipids partly enter the human body with food, partly they are able to synthesize endogenously. The splitting of the main part of dietary lipids occurs in the duodenum 12 under the influence of pancreatic juice secreted by the pancreas and bile acids in the bile. Having split, they are resynthesized again in the intestinal wall and, already in the composition of special transport particles ─ lipoproteins, ─ are ready to enter the lymphatic system and the general bloodstream.

With food, a person needs to get about 50-100 grams of fat every day, which depends on the state of the body and the level of physical activity.

Classification

The classification of lipids, depending on their ability to form soaps under certain conditions, divides them into the following classes of lipids:

Saponified. The so-called substances that, in an environment with an alkaline reaction, form salts of carboxylic acids (soaps). This group includes simple lipids, complex lipids. Both simple and complex lipids are important for the body, they have a different structure and, accordingly, lipids perform different functions.
Unsaponifiables. They do not form carboxylic acid salts in an alkaline medium. This biological chemistry includes fatty acids, derivatives of polyunsaturated fatty acids ─ eicosanoids, cholesterol, as the most prominent representative of the main class of sterols-lipids, as well as its derivatives ─ steroids and some other substances, for example, vitamins A, E, etc.

General classification of lipids

Fatty acid

Substances that belong to the group of so-called simple lipids and are of great importance for the body are fatty acids. Depending on the presence of double bonds in the non-polar (water-insoluble) carbon "tail", fatty acids are divided into saturated (do not have double bonds) and unsaturated (have one or even more double carbon-carbon bonds). Examples of the first: stearic, palmitic. Examples of unsaturated and polyunsaturated fatty acids: oleic, linoleic, etc.

It is the unsaturated fatty acids that are especially important for us and must be taken with food.

Why? Because they:

Serve as a component for the synthesis of cell membranes, participate in the formation of many biologically active molecules.
They help to maintain the normal functioning of the endocrine and reproductive systems.
They help prevent or slow down the development of atherosclerosis and many of its consequences.

Fatty acids are divided into two large groups: unsaturated and saturated

Inflammatory mediators and more

Another type of simple lipids are such important mediators of internal regulation as eicosanoids. They have a unique (like almost everything in biology) chemical structure and, accordingly, unique chemical properties. The main basis for the synthesis of eicosanoids is arachidonic acid, which is one of the most important unsaturated fatty acids. It is eicosanoids that are responsible in the body for the course of inflammatory processes.

Their role in inflammation can be briefly described as follows:

They change the permeability of the vascular wall (namely, increase its permeability).
Stimulates the release of leukocytes and other cells of the immune system into the tissue.
With the help of chemicals, they mediate the movement of immune cells, the release of enzymes and the absorption of particles foreign to the body.

But the role of eicosanoids in the human body does not end there, they are also responsible for the blood coagulation system. Depending on the developing situation, eicosanoids can dilate blood vessels, relax smooth muscles, reduce aggregation, or, if necessary, cause opposite effects: vasoconstriction, contraction of smooth muscle cells and thrombus formation.

Eicosanoids - a large group of physiologically and pharmacologically active compounds

Studies were carried out according to which people who received sufficient amounts of the main substrate for the synthesis of eicosanoids ─ arachidonic acid ─ with food (found in fish oil, fish, vegetable oils) suffered less from diseases of the cardiovascular system. Most likely, this is due to the fact that such people have a more perfect exchange of eicosanoids.

Substances of a complex structure

Complex lipids are a group of substances that are no less important for the body than simple lipids. The main properties of this group of fats:

Participate in the formation of cell membranes, along with simple lipids, and also provide intercellular interactions.
They are part of the myelin sheath of nerve fibers, which is necessary for the normal transmission of nerve impulses.
They are one of the important components of a surfactant ─ a substance that ensures breathing processes, namely, prevents the alveoli from collapsing during exhalation.
Many of them play the role of receptors on the cell surface.
The significance of some complex fats secreted from cerebrospinal fluid, nervous tissue, and heart muscle is not fully understood.

The simplest representatives of this group of lipids include phospholipids, glyco- and sphingolipids.

Cholesterol

Cholesterol is a substance of a lipid nature with the most important value in medicine, since the violation of its metabolism negatively affects the state of the whole organism.

Some of the cholesterol is ingested with food, and some is synthesized in the liver, adrenal glands, gonads and skin.

It also participates in the formation of cell membranes, the synthesis of hormones and other chemically active substances, and also participates in the metabolism of lipids in the human body. Indicators of cholesterol in the blood are often studied by doctors, as they show the state of lipid metabolism in the human body as a whole.

Lipids have their own special transport forms ─ lipoproteins. With their help, they can be carried with the blood stream without causing embolism.

Disorders of fat metabolism are most rapidly and clearly manifested by disorders of cholesterol metabolism, the predominance of atherogenic carriers (the so-called low and very low density lipoproteins) over antiatherogenic (high density lipoproteins).

The main manifestation of lipid metabolism pathology is the development of atherosclerosis.

It manifests itself as a narrowing of the lumen of arterial vessels throughout the body. Depending on the prevalence in the vessels of various localizations, a narrowing of the lumen of the coronary vessels develops (accompanied by angina pectoris), cerebral vessels (with impaired memory, hearing, possible headaches, noise in the head), renal vessels, vessels of the lower extremities, vessels of the digestive system with corresponding symptoms ...

Thus, lipids are at the same time an indispensable substrate for many processes in the body and, at the same time, when fat metabolism is disturbed, they can cause many diseases and pathological conditions. Therefore, fat metabolism requires control and correction when such a need arises.

Fat-like substances lipids are components that take part in vital processes in the human body. There are several groups that perform the leading functions of the body, such as the formation of hormonal levels or metabolism. In this article, we will tell you in detail what it is and what is the role in life processes.

Lipids are organic compounds that include fats and other fat-like substances. They are actively involved in the process of cell structure and are part of the membranes. Affect the throughput of cell membranes, as well as enzymatic activity. They influence the creation of intercellular connections and a variety of chemical processes in the body. They are insoluble in water, but they dissolve in organic solvents (such as gasoline or chloroform). In addition, there are types that are soluble in fats.

This substance can be of vegetable or animal origin. If we are talking about plants, then most of them are in nuts and seeds. Of animal origin, they are mainly located in the subcutaneous tissue, nervous and cerebral.

Lipid classification

Lipids are present in almost all tissues of the body and in the blood. There are several classifications below we give the most common, based on the features of the structure and composition. By structure, they are divided into 3 large groups, which are subdivided into smaller ones.

The first group is simple. They include oxygen, hydrogen and carbon. They are divided into the following types:

Fatty alcohols. Substances containing from 1 to 3 hydroxyl groups.
Fatty acid. Found in a variety of oils and fats.
Fatty aldehydes. The molecule contains 12 carbon atoms.
Triglycerides. These are exactly the fats that are deposited in the subcutaneous tissues.
The bases are sphingosine. They are located in plasma, lungs, liver and kidneys, and are found in nerve tissues.
Waxes. These are esters of high molecular weight fatty acids and alcohols.
Saturated hydrocarbons. They have exclusively single bonds, while the carbon atoms are in a state of hybridization.

The second group is complex. They, like simple ones, include oxygen, hydrogen and carbon. But, besides them, they also contain various additional components. In turn, they are divided into 2 subgroups: polar and neutral.

The polar ones are:

Glycolipids. They appear after the combination of carbohydrates with lipids.
Phospholipids. These are esters of fatty acids, as well as polyhydric alcohols.
Sphingolipids. They are derivatives of aliphatic aminoalcohols.

Neutral ones include:

Acylglycerides. Includes monoglycerides and diglycerides.
N-acetylethanolamides. They are fatty acid ethanolamides.
Ceramides. They include fatty acids in combination with sphingosine.
Esters of sterols. They are complex cyclic alcohols with high molecular weight. They contain fatty acids.

The third group is oxylipids. Substances appear as a result of oxygenation of polyunsaturated fatty acids. In turn, they are divided into 2 types:

Cyclooxygenase pathway.
Lipoxygenase pathway.

Significance for membrane cells

increase

The cell membrane is what separates the cell from the environment around it. In addition to protection, it performs a fairly large number of functions necessary for normal life. The value of lipids in the membrane cannot be overestimated.

In the cell wall, the substance forms a double layer. This helps the cells to interact normally with the environment. Therefore, there are no problems with the control and regulation of metabolism. Membrane lipids maintain the shape of the cell.

Part of a bacterial cell

An integral part of the cell structure is bacterial lipids. As a rule, in the composition of waxes or phospholipids. But the amount of the substance directly varies within 5-40%. The content depends on the type of bacteria, for example, the diphtheria bacillus contains about 5%, but the tuberculosis pathogen contains more than 30%.

A bacterial cell differs in that the substances in it are associated with other constituents, for example, proteins or polysaccharides. In bacteria, they have many more varieties and perform many tasks:

accumulation of energy;
participate in metabolic processes;
are a constituent of membranes;
the resistance of the cell to acids depends on them;
components of antigens.

What functions do they perform in the body?

Lipids are an integral part of almost all tissues of the human body. There are different subspecies, each of which is responsible for some specific function. Next, we will dwell in more detail on what is the value of a substance for life:

Energy function. They tend to disintegrate and a lot of energy appears in the process. It is needed by the cells of the body to support processes such as air intake, the formation of substances, growth and respiration.
Backup function. In the body, fats are stored in reserve, it is from them that the fatty layer of the skin consists. If hunger occurs, then the body uses these reserves.
Thermal insulation function. The fat layer does not conduct heat well, and therefore it is much easier for the body to maintain the temperature.
Structural function. This applies to cell membranes, because the substance is their permanent component.
Enzymatic function. One of the secondary functions. They help cells to form enzymes and help with the assimilation of some trace elements from outside.
Transport function. A side effect is the ability of certain types of lipids to transfer substances.
Signal function. It is also secondary and simply supports some of the body's processes.
Regulatory function. This is another mechanism that has a side effect. By themselves, they almost do not participate in the regulation of various processes, but are a component of substances that directly affect them.

Thus, it is safe to say that the functional significance of lipids for the body is difficult to overestimate. Therefore, it is important that their level is always normal. Many biological and biochemical processes in the body are tied to them.

What is lipid metabolism

Lipid metabolism is a physiological or biochemical process that occurs in cells. Let's take a closer look at them:

Triaciglycerol metabolism.
Exchange of phospholipids. They are unevenly distributed. There are many of them in the liver and plasma (up to 50%). The half-life is 1-200 days, depending on what kind.
Cholesterol exchange. It is formed in the liver and is ingested with food. The surplus is removed naturally.
Fatty acid catabolism. It occurs during β-oxidation, less often α-or ω-oxidation is involved.
Are included in the metabolic processes of the gastrointestinal tract. Namely, the breakdown, digestion and absorption of these substances supplied with food. Digestion begins in the stomach with an enzyme called lipase. Further in the intestine, pancreatic juice and bile enter into action. The reason for the appearance of failures may be a violation of the secretion of the gallbladder or pancreas.
Lipogenesis. Simply put, the synthesis of fatty acids. Occurs in the liver or adipose tissue.
This includes the transport of various fats from the intestines.
Lipolysis Catabolism, which occurs with the participation of lipase and provokes the breakdown of fats.
Synthesis of ketone bodies. Acetoacetyl-CoA gives rise to their formation.
Interconversion of fatty acids. From the fatty acids found in the liver, acids characteristic of the body are formed.

Lipids are an important substance that affects almost all areas of life. The most common in the human diet are triglycerides and cholesterol. Triglycerides are an excellent source of energy, it is this type that forms the body fat. Cholesterol also affects the metabolic processes of the body, as well as the formation of hormonal levels. It is important that the content is always within the normal range, not exceeding or underestimating it. An adult needs to consume 70-140 g of lipids.

Lipids are the most important source of the body's energy reserves. The fact is obvious even at the nomenclature level: the Greek "lipos" is translated as fat. Accordingly, the category of lipids unites fat-like substances of biological origin. The functional of the compounds is quite diverse, which is due to the heterogeneity of the composition of this category of bio-objects.

What functions do lipids perform?

List the main functions of lipids in the body, which are the main ones. At the introductory stage, it is advisable to highlight the key roles of fat-like substances in the cells of the human body. The basic list is the five functions of lipids:

reserve energy;
structure-forming;
transport;
insulating;
signal.

The secondary tasks that lipids perform in combination with other compounds include a regulatory and enzymatic role.

Energy reserve of the body

This is not only one of the important, but the priority role of fat-like compounds. In fact, part of the lipids is the energy source of the entire cell mass. Indeed, fat for cells is analogous to fuel in a car's tank. The energy function is realized by lipids as follows. Fats and similar substances are oxidized in the mitochondria, breaking down to the level of water and carbon dioxide. The process is accompanied by the release of a significant amount of ATP - high-energy metabolites. Their supply allows the cell to participate in energy-dependent reactions.

Structural blocks

At the same time, lipids carry out a building function: with their help, the cell membrane is formed. The process involves the following groups of fat-like substances:

cholesterol - lipophilic alcohol;
glycolipids - compounds of lipids with carbohydrates;
phospholipids are esters of complex alcohols and higher carboxylic acids.

It should be noted that in the formed membrane, fats are not directly contained. The formed wall between the cell and the external environment turns out to be two-layer. This is achieved due to the biphilicity. A similar characteristic of lipids indicates that one part of the molecule is hydrophobic, that is, insoluble in water, while the other, on the contrary, is hydrophilic. As a result, a cell wall bilayer is formed due to the ordered arrangement of simple lipids. Molecules unfold in hydrophobic regions towards each other, while hydrophilic tails are directed inward and outward of the cell.

This determines the protective functions of membrane lipids. First, the membrane gives the cell its shape and even preserves it. Secondly, the double wall is a kind of passport control point that does not allow unwanted visitors to pass through.

Autonomous heating system

Of course, this name is rather arbitrary, but it is quite applicable if we consider what functions lipids perform. The compounds do not so much heat the body as they keep the heat inside. A similar role is assigned to fatty deposits that form around various organs and in the subcutaneous tissue. This class of lipids is characterized by high heat-insulating properties, which protects vital organs from hypothermia.

Did you order a taxi?

The transport role of lipids is referred to as a secondary function. Indeed, the transfer of substances (mainly triglycerides and cholesterol) is carried out by separate structures. These are bound complexes of lipids and proteins called lipoproteins. As you know, fat-like substances are insoluble in water, respectively, in blood plasma. In contrast, the functions of proteins include hydrophilicity. As a result, the lipoprotein core is an accumulation of triglycerides and cholesterol esters, while the membrane is a mixture of protein and free cholesterol molecules. As such, lipids are delivered to the tissues or back to the liver for elimination from the body.

Secondary factors

The list of already listed 5 functions of lipids complements a number of equally important roles:

enzymatic;
signal;
regulatory

Signal function

Some complex lipids, in particular their structure, allow the transmission of nerve impulses between cells. Glycolipids act as mediators in this process. No less important is the ability to recognize intracellular impulses, which is also realized by fat-like structures. This allows you to select substances necessary for the cell from the blood.

Enzymatic function

Lipids, regardless of their location in the membrane or outside it, are not part of the enzymes. However, their biosynthesis occurs with the presence of fat-like compounds. Additionally, lipids are involved in protecting the intestinal wall from pancreatic enzymes. The excess of the latter is neutralized by bile, where cholesterol and phospholipids are included in significant quantities.