Interesting facts about lipids. Lipids - what are they? Lipids: functions, characteristics. Disturbance of normal blood lipid concentrations

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Lipids in nutrition

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

Most people eat a fairly varied diet, and their body gets all the necessary lipids. 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 essential 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 to produce energy. This is why when fasting a person loses weight and becomes weaker. Deprived of energy, the body begins to consume lipid reserves from subcutaneous fat.

Thus, lipids play a very important role in healthy eating person. However, for some diseases or disorders, their quantity should be strictly limited. Patients usually learn about this from their 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 broken down according to its composition into proteins, carbohydrates and lipids, which together make up the bulk. Each of these substances breaks down in the body, releasing a certain amount of energy. Proteins and carbohydrates are digested more easily, but the breakdown of 1 g of these substances releases about 4 Kcal ( kilocalories) energy. Fats are more difficult to digest, but the breakdown of 1 g releases about 9 kcal. Thus, energy value lipids is the highest.

In terms of energy release, triglycerides play the largest role. Saturated acids, included in these substances, are absorbed by the body by 30–40%. Monounsaturated and polyunsaturated fatty acids are completely absorbed by a healthy body. Adequate lipid intake allows carbohydrates and proteins to be used for other purposes.

Plant and animal lipids

All lipids entering the body with food can be divided into animal substances 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 explained by differences in the functioning of cells in plants and animals.

Examples of plant and animal lipid sources

Each lipid source has certain 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, excess animal fat increases the risk of developing a number of diseases associated with lipid metabolism in the body ( atherosclerosis, cholelithiasis, etc.). Plant foods contain fewer lipids, but the body cannot synthesize them on its own. Not even a large number of seafood, citrus fruits or nuts supply enough polyunsaturated fatty acids, which 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, to maintain health, it is recommended to make your 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 be harmful to health. First of all, this concerns saturated fatty acids, most of which are deposited in the body and often lead to obesity. The optimal solution is to maintain the required proportions between proteins, fats and carbohydrates. The body must receive the same number of calories that it expends during the day. This is why lipid intake rates may vary.

The body's need for lipids can be influenced by the following factors:

Body weight. Overweight people have to expend more energy. If they are not going to lose weight, then the need for calories and, accordingly, lipids will be slightly higher. If they want to lose weight, then, first of all, they need to limit fatty foods.
Loads during the day. People doing heavy lifting physical work, or athletes need a lot of energy. If the average person has 1500 - 2500 calories, then for miners or loaders the norm can reach 4500 - 5000 calories per day. Of course, the need for lipids also increases.
Nature of nutrition. Every country and every people has its own food traditions. When calculating the optimal diet, you need to take into account exactly what 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 intake is kept to a minimum.
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 gall bladder, since these organs are responsible for the digestion and absorption of lipids.
The age of the person. IN childhood Metabolism is faster and the body requires more energy for normal growth and development. In addition, children usually do not have serious problems with the gastrointestinal tract, and they digest any food well. It should also be taken into account that infants receive an optimal set of lipids through breast milk. Thus, age greatly influences the rate of fat intake.
Floor. It is believed that on average a man consumes more energy than a woman, so the norm of fat in men's diet is slightly higher. However, in pregnant women, the need for lipids increases.

It is estimated 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 approximately 25 - 30% of this energy, which corresponds to 70 - 80 g of lipids. Of these, saturated fatty acids should make up about 20%, and polyunsaturated and monounsaturated fatty acids should make up about 40% each. It is also recommended to give preference to lipids of plant origin ( about 60% of the total).

It is difficult for a person to make the necessary calculations on his own and take into account all the factors to select the optimal diet. To do this, it is better to consult a nutritionist or food hygiene specialist. After a short survey and clarification of the nature of nutrition, they will be able to create an optimal daily diet that the patient will adhere to in the future. They can also recommend specific foods that contain essential lipids.

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

Almost all food products contain lipids in varying quantities. However, in general, animal products are richer in these substances. In plants mass fraction 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 product packaging in the section “ the nutritional value" 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 products and dishes.

Mass fraction of lipids in staple foods

In most products of plant origin ( vegetables, fruits, herbs, root vegetables) the mass fraction of fats is no more than 1 – 2%. The exceptions are citrus fruits, where the proportion of lipids is slightly higher, and vegetable oils, which are a concentrate of lipids.

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

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

Essential fatty acids and their main dietary sources

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

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

Both deficiency and excess of lipids in the diet can seriously affect the health of the body. In this case, we are not talking about one-time intake of large amounts of fat ( although this may cause 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, if there is a lack of lipids in food, the most important substances for the body will still be synthesized by the body’s own cells, and energy needs will be covered by the breakdown of fat reserves. If there is an excess of lipids in the diet, a significant part will not be absorbed in the intestine and will leave the body with fecal matter, and some of the lipids that enter the blood will be transformed into adipose tissue. However, these adaptation mechanisms are temporary. Moreover, they only work well in healthy body.

Possible consequences of lipid imbalance in the diet

Blood and plasma lipids

A significant portion 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 primarily as lipoproteins. The levels of various lipids in the blood can be determined using biochemical blood tests. This makes it possible to identify a number of disorders and suspect corresponding pathologies.

Triglycerides

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

Free fatty acids

Free fatty acids enter the blood as a result of the breakdown of triglycerides. Normally, they are deposited in adipose tissue. Modern research showed a relationship between the level of free fatty acids in the blood and some pathological processes. For example, in people with high concentration fatty acids ( on an empty stomach) 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 normal limits 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 disruption of its absorption by the body can lead to the development of serious diseases.

In the human body, cholesterol performs the following functions:

imparts rigidity to cell membranes;
takes part in the synthesis of steroid hormones;
is part of bile;
participates in the absorption of vitamin D;
regulates the permeability of the walls of certain cells.

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

The term lipoproteins or lipoproteins refers to 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 because, due to their small size, they can pass through the walls of blood vessels and “cleanse” them of lipid deposits. Thus, high HDL levels reduce the risk of developing atherosclerosis.
Low density. LDL) transport cholesterol and other lipids from the liver ( places of their synthesis) to tissues. From a medical point of view, this fraction of lipoproteins is harmful, since it is LDL that promotes the deposition of lipids on the walls of blood vessels with the formation of atherosclerotic plaques. High LDL levels greatly increase the risk of developing atherosclerosis.
Average ( intermediate) density. Intermediate density lipoproteins ( BOB) do not have significant diagnostic value, since they are an intermediate product of lipid metabolism in the liver. They also transport lipids from the liver to other tissues.
Very low density. VLDL) transport lipids from the liver to tissues. They also increase the risk of developing atherosclerosis, but play a minor role in this process ( after LDL).
Chylomicrons. Chylomicrons are significantly larger than other lipoproteins. They form in the walls small intestine and transport lipids supplied with food to other organs and tissues. In the development of various pathological processes these substances do not play a significant role.

Currently disclosed biological role and diagnostic value of most lipoproteins, but some questions still exist. 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 various lipids in the blood. Usually this is done deoxygenated blood. The patient is sent for analysis by the attending physician. The most important lipids (total cholesterol, triglycerides) are determined in biochemical analysis blood. If the patient needs a more detailed examination, the doctor indicates which lipids need to be determined. The analysis itself usually lasts several hours. Most laboratories provide results the next day.

What is a lipid profile?

A lipidogram is a set of laboratory blood tests aimed at determining the level of lipids in the blood. This is the most useful research for patients with various disorders 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 to diagnose 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.

The 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 may 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 “clean” blood vessels from excess cholesterol and are beneficial for the body. Low level HDL indicates that the body does not absorb fat well.
Very low density lipoproteins ( VLDL). They have a 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 atherogenicity coefficient, which reflects the risk of developing atherosclerosis.

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

Before taking the test, patients should consider the following recommendations:

You can eat in the evening before the test, but you should not overeat fatty foods. It is better to stick to your usual diet.
The day before the test, it is necessary to exclude various types of loads ( both physical and emotional), as they can lead to the breakdown of fat reserves in the body and increase blood lipid levels.
In the morning, immediately before donating blood, you should not smoke.
Regular use of a number of drugs also affects the level of lipids in the blood ( contraceptive drugs, hormonal drugs and etc.). It is not necessary to cancel them, but this fact must 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 lipid levels

The limits of the norm are somewhat different for all people. It depends on gender, age, availability chronic pathologies and a number of other indicators. However, there are certain limits, exceeding which clearly indicates the presence of problems. The table below shows generally accepted normal limits for various blood lipids.
The limits of the norm are relative, and the patient himself cannot always draw the right conclusions when interpreting the results of the analysis. When reviewing the results, the attending physician will definitely take into account that during pregnancy the normal limits expand, as well as during fasting. Therefore, there is no need to panic if there are some deviations from the norm. In any case, the final conclusion must be made by the attending physician.

Diseases associated with lipid metabolism

There are quite a few diseases that are, to one degree or another, related to 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 tests. Other pathologies are a consequence of lipid imbalance.

Lipid metabolism disorders ( dyslipidemia)

Excess or lack of lipids in the diet can lead to a variety of pathologies. In a healthy body that normally absorbs all incoming substances, this imbalance does not affect metabolic processes as much. For example, excess lipids do not always lead to obesity. To do this, a person must also have genetic predisposition, endocrine disorders, or he must lead sedentary lifestyle life. In other words, the amount of lipids in the diet in most cases is only one of many factors influencing the occurrence 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 gastrointestinal tract (pancreatitis, cholelithiasis, etc.).

Lack of dietary lipids 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 errors made during blood donation. Patients do not donate blood on an empty stomach, which is why lipid levels do not have time to normalize, and the doctor may mistakenly suspect some problems. However, there are many pathologies that cause disturbances in blood lipids, regardless of nutrition.

Pathological conditions associated with changes in the amount of lipids in the blood are called dyslipidemia. They are also divided into several types. If the level of triglycerides in the blood is elevated, they speak of hypertriglyceridemia ( synonym – hyperlipemia). If cholesterol levels increase, they speak of hypercholesterolemia.

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

Primary. Primary dyslipidemias generally mean genetic diseases and deviations. 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 dyslipidemia refers to pathological conditions in which an increase in lipids in the blood 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 to make a correct diagnosis based on test results and the patient’s symptoms. Secondary dyslipidaemias are more common and are usually the first to be excluded. Primary dyslipidemias are much less common, but they are much more difficult to diagnose and treat.

There are five main types of primary hyperlipoproteinemia ( increased level lipoproteins):

Hyperchylomicronemia. With this disease, the level of triglycerides in the blood increases, while the level of other lipids usually remains within normal limits. Patients may experience paroxysmal abdominal pain, but without muscle tension abdominals. Xanthomas may appear on the skin ( 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. The analysis showed significantly higher cholesterol levels. Triglyceride levels may be normal or slightly elevated. Patients also develop xanthomatosis ( xanthomas on the skin). The risk of atherosclerosis increases significantly. With this disease, myocardial infarction is possible even at a young age.
Familial hypercholesterolemia with hyperlipemia. The levels of both cholesterol and triglycerides in the blood are significantly elevated. Xanthomas are large and appear after 20–25 years. Increased risk of developing atherosclerosis.
Hyper-pre-beta lipoproteinemia. In this case, the level of triglycerides increases, and the level of cholesterol remains within normal limits. The disease is often combined with diabetes mellitus, gout or obesity.

Essential hyperlipemia also sometimes occurs ( Buerger-Grütz disease). The above diseases are diagnosed based on electrophoresis data. You can suspect one of these pathologies as follows. U healthy people After eating a lot of fatty foods, lipemia is observed ( mainly due to the level of chylomicrons and beta-lipoproteins), which disappears after 5–6 hours. If blood triglyceride levels do not decrease, tests should be performed to identify primary hyperlipoproteinemia.

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

Diabetes. In this case, the excess lipids in the blood are explained by the transformation of excess carbohydrates.
Acute pancreatitis. With this disease, the absorption of lipids is disrupted, 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 also regulate lipid metabolism in the body.
Intrahepatic cholestasis and other liver pathologies. The liver takes part in the synthesis of most lipids, necessary for the body. With various hepatitis, bile outflow disorders and other pathologies of the liver and bile ducts, the level of lipids in the blood may increase.
Nephrotic syndrome. This syndrome develops when the glomerular apparatus of the kidneys is damaged. Patients experience severe renal edema. The level of proteins in the blood drops, and the level of cholesterol increases significantly.
Porphyria. Porphyria is a disease with a hereditary predisposition. In patients, the metabolism of a number of substances is disrupted, as a result of which porphyrins accumulate in the blood. In parallel, lipid levels may increase ( sometimes significantly).
Some autoimmune diseases. At autoimmune diseases Antibodies produced by the body attack its own cells. In most cases, chronic inflammatory processes develop, which are associated with increased lipid levels.
Gout. With gout, the metabolism of uric acid in the body is disrupted, 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 pathologies of the liver and gastrointestinal tract. A number of enzymes may be activated that increase blood lipid levels.
Taking certain medications. Increased lipid levels can result from, for example, long-term use oral contraceptives ( contraception ). Most often, this side effect is mentioned in the instructions for the corresponding drug. Before taking the test, you should not take such drugs, or you should warn the treating physician about this so that he can correctly interpret the test results.

In the vast majority of cases, the cause of persistently elevated blood lipid levels is one of the above problems. It should also be noted that elevated lipid levels can be quite long time after serious injuries or previous myocardial infarction.

Also, increased levels of lipoproteins in the blood can be observed during pregnancy. This increase is usually minor. When lipid levels increase 2 to 3 times higher than normal, the likelihood of pregnancy in combination with other pathologies must be considered, causing an increase lipid levels.

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

healthy digestive system is collateral good absorption lipids and other nutrients. A significant imbalance of lipids in food over a long period of time can lead to the development of certain gastric pathologies. One of the most common problems in cardiology is atherosclerosis. This disease occurs due to the deposition of lipids in blood vessels ( mainly in arteries). As a result of this process, the lumen of the vessel narrows and blood flow becomes difficult. Depending on which arteries are affected by atherosclerotic plaques, patients may experience various symptoms. The most common type is high blood pressure, ischemic disease hearts ( 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 very arbitrary. In addition to the chemical nature of substances, the development of this disease Many other factors also contribute.

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

heavy smoking;
heredity;
diabetes;
overweight ( obesity);
sedentary lifestyle ( physical inactivity) 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 “anti-atherogenic”, 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 transform into atherosclerotic plaques. But this depends on the metabolism in the body. In general, however, it is believed that significant excess of any lipid in the diet predisposes to the development of atherosclerosis. Before use, you should consult a specialist.

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

In fact, 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 1g of fat supplies more calories than proteins and carbohydrates in double quantity. The body does not burn all fats at once, but puts some of them in storage as a reserve to be used in the future as needed. We bring you information about fats that will help you look at fats in a new way.

Why is fat necessary for our body?

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

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

By forming subcutaneous fatty tissue, 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 minerals, since without fats their absorption in the body is impossible,

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

Fats produce female sex hormones, which is especially important in postmenopause, when ovarian function has practically disappeared. They also play an important role during the reproductive period, as they maintain hormonal levels at the proper level. If the level of adipose tissue in the body is below 10-15%, then hormonal imbalance up to the cessation of the menstrual cycle,

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

Almost 35% daily diet must consist of fats. Wherein significant role plays a type of fat.

Which fats are healthy and which are not?

Depending on their chemical structure, fats are divided into saturated and unsaturated fatty acids. Saturated fatty acids contain large amounts of hydrogen ions and are found in foods of animal origin. These are precisely the fats that are deposited on the stomach, thighs, and buttocks. This is a kind of energy reserve of the body. Saturated fats hinder growth muscle mass because they reduce the effect of insulin. But at the same time, they are the basis for the production of testosterone. When they are excluded from food, the level of this hormone, important for men, also decreases. The same can be achieved by consuming them excessively. 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, such as olive or vegetable oil, fish oil. These fats are not stored in the body, but are completely burned. They are a beneficial nutritional component for the body and a raw material 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 cookies, as well as fast food. They are used primarily for food storage and increase the risk of developing oncological diseases and diseases from of cardio-vascular system.

Omega-3 and Omega-6 are unsaturated fatty acids.

Of all types of fats, these fatty acids 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 for the body are also found in flaxseed, nut and soybean oils. Salmon, mackerel and herring also contain them sufficient quantity.

Omega-3 and Omega-6 fatty acids:

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

Reduces cholesterol levels,

Strengthens the walls of blood vessels,

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

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

Ideally, you should mix saturated and unsaturated fats For example, season meat dishes and salads with rapeseed oil.

Which is better, margarine or butter?

Unlike butter, margarine contains more unsaturated fatty acids. But according to new teachings, this does not mean that the oil is more harmful. In terms of calories, both products are almost equal. But margarine contains harmful trans fats, which contribute to the growth of several diseases.

If you are a fan of margarine, then it is better to choose high-quality types with low content solid fats.

Do fats lead to obesity?

Although fat contains more calories, there is no proven link between fat intake and increased weight.

Excess calories lead to obesity: those who consume more calories than they burn gain weight. Food containing sufficient amounts of fat satiates us for a long period and allows us to eat less.

Those who, on the contrary, try to save on fats, often eat more carbohydrates. Cereal products such as White bread And pasta increase blood sugar levels, and with it insulin, which leads to the growth of adipose tissue. In addition, saturation of the body occurs quickly, but does not last long, resulting in 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 given by biochemistry, which studies these and other substances that are of great importance for metabolism.

What it is

Lipids are organic matter, insoluble in water. The functions of lipids in the human body are diverse.

Lipids - this word means "small particles of fat"

This is first of all:

Energy. Lipids serve as a substrate for storing and using energy. When 1 gram of fat is broken down, approximately 2 times more energy is released than when protein or carbohydrates of the same weight are broken down.
Structural function. The structure of lipids determines the structure of the membranes of the cells of our body. They are arranged in such a way that the hydrophilic part of the molecule is located inside the cell, and the hydrophobic part is on its surface. Thanks to these properties of lipids, each cell, on the one hand, is 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 our skin and serves as a kind of barrier between us and the outside world is also made up of lipids. In addition, they, as part of adipose tissue, provide 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 their structural features. They have dual properties, since they have a soluble and insoluble part in the molecule.

Entry into the body

Lipids partly enter the human body with food, and partly can be synthesized endogenously. Splitting the main part dietary lipids occurs in the duodenum under the influence of pancreatic juice secreted by the pancreas and bile acids as part of bile. Having broken down, they are resynthesized again in the intestinal wall and, already as part of special transport particles ─ lipoproteins, ─ are ready to enter the lymphatic system and general blood flow.

A person needs to receive about 50-100 grams of fat from food every day, which depends on the condition of the body and the level of physical activity.

Classification

Classification of lipids depending on their ability to form soaps certain conditions divides them into the following classes of lipids:

Saponifiable. This is the name for substances that, in an environment with 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 different structure and, accordingly, lipids perform different functions.
Unsaponifiable. In an alkaline environment they do not form salts carboxylic acids. 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 carbon-carbon double bonds). Examples of the first: stearic, palmitic. Examples of unsaturated and polyunsaturated fatty acids: oleic, linoleic, etc.

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

Why? Because they:

They serve as a component for the synthesis of cell membranes and participate in the formation of many biologically active molecules.
Help maintain normal functioning of the endocrine and reproductive systems.
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: important mediators internal regulation, like eicosanoids. They have a unique (like almost everything in biology) chemical structure and, accordingly, unique Chemical properties. The main basis Arachidonic acid, which is one of the most important unsaturated fatty acids, is used for the synthesis of eicosanoids. It is eicosanoids that are responsible for the course of inflammatory processes in the body.

Their role in inflammation can be briefly described as follows:

They change the permeability of the vascular wall (namely, they increase its permeability).
Stimulate the release of leukocytes and other cells of the immune system into tissues.
By using chemical substances 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 current situation, eicosanoids can dilate blood vessels, relax smooth muscles, reduce aggregation or, if necessary, cause the opposite effects: vasoconstriction, contraction of smooth muscles. muscle cells and thrombus formation.

Eicosanoids are a large group of physiologically and pharmacologically active compounds.

Studies have been conducted according to which, people who received sufficient quantities of the main substrate for the synthesis of eicosanoids - arachidonic acid - with food (found in fish oil, fish, vegetable oils) suffered less from cardiovascular diseases. Most likely, this is due to the fact that such people have a more advanced eicosanoid metabolism.

Substances of 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:

They 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, necessary for the normal transmission of nerve impulses.
They are one of the important components surfactant ─ a substance that ensures breathing processes, namely preventing the collapse of the alveoli during exhalation.
Many of them play the role of receptors on the surface of cells.
The significance of some complex fats secreted from cerebrospinal fluid, nervous tissue, cardiac muscle is not fully understood.

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

Cholesterol

Cholesterol is a substance of lipid nature with the most important value in medicine, since disruption of its metabolism negatively affects the condition of the entire organism.

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

It is also involved in the formation of cell membranes, the synthesis of hormones and other chemicals. active substances, and also participates in lipid metabolism in the human body. Indicators of cholesterol in the blood are often examined 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 transported through the bloodstream without causing embolism.

Violations fat metabolism They are most quickly and clearly manifested by disorders of cholesterol metabolism, the predominance of atherogenic carriers (the so-called low- and very low-density lipoproteins) over anti-atherogenic ones (high-density lipoproteins).

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

It manifests itself by narrowing the lumen of arterial vessels throughout the body. Depending on the predominance in blood vessels various localizations narrowing of the lumen develops coronary vessels(accompanied by angina), cerebral vessels (with impaired memory, hearing, possible headaches, noise in the head), kidney vessels, blood vessels lower limbs, vessels of the digestive organs with corresponding symptoms.

Thus, lipids are at the same time an indispensable substrate for many processes in the body and, at the same time, if lipid metabolism is disturbed, they can cause many diseases and pathological conditions. Therefore, fat metabolism requires monitoring and correction when the 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 main functions of the body, such as the formation hormonal levels or metabolism. In this article we will explain in detail what it is and what its role is in life processes.

Lipids are organic compound, which includes fats and other fat-like substances. They actively participate in the process of cell structure and are part of membranes. They affect the permeability of cell membranes, as well as enzymatic activity. They influence the creation of intercellular connections and a variety of chemical processes in organism. Insoluble in water, but they dissolve in solvents organic origin(such as gasoline or chloroform). In addition, there are types that are fat soluble.

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

Classification of lipids

Lipids are present in almost all tissues of the body and in the blood. There are several classifications; below we present the most common one, based on the characteristics of structure and composition. According to their 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 various oils and fats.
Fatty aldehydes. The molecule contains 12 carbon atoms.
Triglycerides. These are precisely the fats that are deposited in the subcutaneous tissues.
Sphingosine bases. They are located in the plasma, lungs, liver and kidneys, and are found in nerve tissues.
Waxes. These are esters of fatty acids and high molecular weight alcohols.
Saturated hydrocarbons. They have exclusively single bonds, with carbon atoms 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.

Polar ones include:

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

Neutral ones include:

Acylglycerides. Includes monoglycerides and diglycerides.
N-acetylethanolamides. They are ethanolamides of fatty acids.
Ceramides. They contain fatty acids combined with sphingosine.
Sterol esters. They represent complex cyclic alcohols of high molecular weight. They contain fatty acids.

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

Cyclooxygenase pathway.
Lipoxygenase pathway.

Importance for membrane cells

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

In the cell wall, the substance forms a double layer. This helps cells interact normally with their environment. Therefore, there are no problems with controlling and regulating 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, they contain waxes or phospholipids. But the amount of the substance directly varies between 5-40%. The content depends on the type of bacterium, for example, the diphtheria bacillus contains about 5%, but the tuberculosis pathogen already contains more than 30%.

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

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

What functions do they perform in the body?

Lipids component almost all fabrics human body. There are different subspecies, each of which is responsible for a specific function. Next, we will dwell in more detail on the importance of the substance for life:

Energy function. They tend to disintegrate and in the process a lot of energy appears. The body's cells need it to support processes such as air flow, substance formation, growth and respiration.
Backup function. In the body, fats are stored in reserve; they are what make up the fatty layer of the skin. If hunger sets in, the body uses these reserves.
Thermal insulation function. The fat layer conducts heat poorly, and therefore it is much easier for the body to maintain temperature.
Structural function. This applies to cell membranes because the substance is a permanent component of them.
Enzymatic function. One of the secondary functions. They help cells form enzymes and help with the absorption of certain microelements coming from outside.
Transport function. The side effect lies in the ability of some types of lipids to transport substances.
Signal function. It is also secondary and simply supports some body processes.
Regulatory function. This is another mechanism that has a secondary meaning. By themselves, they are almost not involved in the regulation of various processes, but are a component of substances that directly affect them.

Thus, we can say with confidence that the functional importance 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 process of physiological or biochemical nature that occurs in cells. Let's look at them in more detail:

Triacyglycerol metabolism.
Phospholipid metabolism. They are distributed unevenly. There are many of them in the liver and plasma (up to 50%). The half-life is 1-200 days, depending on the type.
Cholesterol exchange. It is formed in the liver and comes with food. Excess is eliminated naturally.
Catabolism of fatty acids. Occurs during β-oxidation; α- or ω-oxidation is less commonly involved.
Included in the metabolic processes of the gastrointestinal tract. Namely, the breakdown, digestion and absorption of these substances coming from food. Digestion begins in the stomach with the help of an enzyme called lipase. Next, pancreatic juice and bile come into action in the intestines. The cause of malfunctions may be a violation of secretion 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 ketone bodies. Acetoacetyl-CoA gives rise to their formation.
Interconversion of fatty acids. From fatty acids found in the liver, acids characteristic of the body are formed.

Lipids are important substance, affecting almost all areas of life. The most common triglycerides and cholesterol in the human diet. Triglycerides are an excellent source of energy; it is this type that forms fat layer bodies. Cholesterol affects the body’s metabolic processes, as well as the formation of hormonal levels. It is important that the content is always within the normal range, neither exceeding nor underestimating it. An adult needs to consume 70-140 g of lipids.

Lipids protrude the most important source energy reserve body. The fact is obvious even at the nomenclature level: the Greek “lipos” is translated as fat. Accordingly, the category of lipids combines fat-like substances biological origin. The functionality of the compounds is quite diverse, which is due to the heterogeneity of the composition of this category of biological objects.

What functions do lipids perform?

List the main functions of lipids in the body, which are basic. 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 regulatory and enzymatic roles.

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 source of energy for the entire cellular mass. Indeed, fat for cells is an analogue of fuel in a car tank. The energy function of lipids is realized in the following way. Fats and similar substances are oxidized in the mitochondria, breaking down to 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.

Building Blocks

At the same time, lipids perform a construction function: with their help, the cell membrane is formed. The following groups of fat-like substances are involved in the process:

cholesterol is a lipophilic alcohol;
glycolipids – compounds of lipids with carbohydrates;
Phospholipids are esters of complex alcohols and higher carboxylic acids.

It should be noted that the formed membrane does not contain fats directly. The resulting wall between the cell and external environment turns out to be two-layer. This is achieved due to biphilicity. This characteristic of lipids indicates that one part of the molecule is hydrophobic, that is, insoluble in water, and the second, on the contrary, is hydrophilic. As a result, a cell wall bilayer is formed due to the ordered arrangement of simple lipids. The molecules turn their hydrophobic regions toward each other, while their hydrophilic tails point inward and outward of the cell.

This determines protective functions membrane lipids. First, the membrane gives the cell its shape and even maintains 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 quite arbitrary, but it is quite applicable if we consider what functions lipids perform. The compounds do not so much heat the body as they retain heat inside. A similar role is assigned to fatty deposits that form around various organs and in 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 considered a secondary function. Indeed, the transfer of substances (mainly triglycerides and cholesterol) is carried out by separate structures. These are linked complexes of lipids and proteins called lipoproteins. As is known, 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 a collection of triglycerides and cholesterol esters, while the shell is a mixture of protein molecules and free cholesterol. In this form, lipids are delivered to the tissues or back to the liver for removal from the body.

Minor Factors

The list of the 5 functions of lipids already listed 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 mediate this process. No less important is the ability to recognize intracellular impulses, also realized by fat-like structures. This allows you to select substances needed by the cell from the blood.

Enzymatic function

Lipids, regardless of their location in the membrane or outside it, are not part of 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.