Functions of fats in the body. The importance of fats for normal and sports life The role of fats in the biological life of organisms

Not enough fat can contribute to health problems

Various types of dietary fats, as well as protein and carbohydrates, are among the main nutrients.

What are fats for?

Fats are one of the most important nutrients necessary for the normal functioning of the human body. They:

• along with carbohydrates are the most important source of energy. One gram of fat, oxidized in the body, gives more than 9 kcal , while one gram of carbohydrate is about 4 kcal;
• How energy substances are part of cell membranes and intracellular formations;
• are part of the nervous tissue;
• necessary for good brain activity, concentration, memory;
• protect the skin from drying out by creating a lipid barrier;
• make the body more resistant to infectious diseases , since fats supply biologically active substances to tissues: phosphatides (phospholipids), fat-soluble vitamins (A, D, E and K);
• promote the production of bile;
• serve to produce hormones and prostaglandins;
• help to use proteins and carbohydrates more efficiently;
• are the only source of essential fatty acids .

Based on the foregoing, the exclusion or sharp restriction of the intake of fats from food in the body can be harmful to human health. When a person needs energy reserves, the body accumulates it in the form of the most high-calorie substances - fats. This is a kind of strategic reserves of the body. It is with the help of these reserves that it is possible to replenish the energy expended on hard physical work and in the course of performing exercise. In addition, it is recommended to eat more fatty foods in the cold season, because it prevents the body from hypothermia.

Not getting enough fat can contribute to health problems, including:

• dry, scaly skin;
• dry, dull hair or hair loss;
• growth retardation;
• low resistance to colds and infectious diseases;
• poor wound healing;
• mood problems, depression, lack of attention.

Types of cholesterol

There is a widespread the belief that cholesterol is extremely unhealthy and is almost the main indicator of the state of our health. However, it is not. It plays an important role in increasing the permeability of cell membranes, for the production of vitamin D in the skin, for the formation of hormones by the adrenal glands.

It is important to remember that there are different types cholesterol. So, taking one blood sample for analysis, you can say:

• about the total level of cholesterol in the human body (in young man it should not exceed 2 g per 1 liter of blood);
• LDL cholesterol (low density lipoprotein). It is also called "bad" cholesterol, because it tends to be deposited on the walls of the arteries, which can lead to blockage (the norm for a young man is no more than 1.3 g per 1 liter);
• HDL cholesterol (high density lipoprotein). It is also considered “good” cholesterol, because it, on the contrary, cleanses the walls of arteries from fatty accumulations. Therefore, the higher the content of this type of cholesterol, the lower the risk cardiovascular diseases . Ideally, its level in men should not be lower than 0.45 g / l.

Fatty acid

Food fats are a complex food product containing lipids, water, mineral salts and vitamins. However, the main integral part fats are lipids (from the Greek. l?pos - fat). This is a large class of chemicals, which are based on triglycerides, which are transformed into fatty acids during the digestive process.

Fatty acids can be divided into essential and essential fatty acids. Essential fatty acids are produced in our body, while essential fatty acids come from foods containing dietary fats.

Types of Dietary Fats

There are three types of fatty acids:

1) saturated;

2) monounsaturated;

3) polyunsaturated.

All natural fats are mixtures of these fats. Therefore, in any "healthy" fat there are "bad" fats. Usually, fatty acids are classified according to the predominant type of dietary fat in their composition.

Saturated fatty acids are found in all types of meat, sausages, poultry skin, whole milk products, butter and cheese, egg yolks, vegetable oils(palm and coconut).

The use of these products causes an increase in total cholesterol and "bad" cholesterol, which contributes to the deposition of fat on the walls of blood vessels, reducing their patency.

Monounsaturated fatty acids are essential fatty acids. They are contained in olive oil, canola oil, peanut oil, cashew nuts, almonds, most other nuts, avocado oil, goose liver, cocoa. They lower the level of total cholesterol and the level of "bad" cholesterol. In addition, they can even increase the level of "good" cholesterol. Therefore, it is advisable to include these products in your daily diet.

Polyunsaturated fatty acids in their origin can be vegetable (hazelnuts, almonds, sunflower, flax, soybeans, rapeseed, peanuts, corn, vegetable margarine, nut butter) and animals (salmon, tuna, fish oil).

They help lower total cholesterol, but, unfortunately, they also lower “good” cholesterol.

Polyunsaturated fatty acids are divided into two subgroups:

• linoleic acid (Omega-6);
• alpha-linoleic acid (Omega-3).

These two acids are just as necessary for the body as vitamins. They are essential fatty acids because they cannot be synthesized in the body.

Linoleic acid (Omega-6). The lack of this acid immediately affects the condition of skin cells, mucous membranes, endocrine glands, and can also lead to vascular lesions.

Omega-6 is found in corn and sunflower oil, nuts, seeds, cottonseed and soybean oil. In the body of an adult healthy person there is a two-month supply of this type of fat. However, older people should take it daily with food.

Alpha-linoleic acid (Omega-3). The lack of this acid leads to a deterioration in the state of cell membranes, especially brain cells, which is expressed in memory disorders, in a decrease in the ability to learn. In addition, the retina of the eyes is affected, which leads to a sharp deterioration in vision.

Contains acid in fish and fish oils, linseed and rapeseed oils, walnut oils, wheat germ oils, hazelnuts, almonds and butter . The average daily norm for a person is 2 g per day.published

Fats are included in a large group of organic compounds under the general name - lipids. This group also includes another fat-like substances - lipoids.

Fats in living organisms are the main type of reserve substances and the main source of energy. In vertebrates, and in humans, about half of the energy that is consumed by living cells at rest is formed due to the oxidation of fatty acids that make up fats. Fats perform a number of other important functions in the body.

* Fat forms protective layers for internal organs: heart, liver, kidneys and so on.

* The membrane lining of all cells in the body is approximately 30% fat.

* Fats are essential for the production of many hormones. They play an important role in the activity of the immune system, and this, as you know, is the body's internal self-healing system.

* Fats deliver fat-soluble vitamins A, D, E, and K to the body.

From the foregoing, we can conclude that various diets that drastically reduce the amount of fat entering the body with food, as well as the constant use of low-fat foods, are harmful to health and will not contribute to the improvement of the body.
Important information about fats

1. Rates of fat consumption individually. It is recommended to eat 1 - 1.3 grams of fat per 1 kilogram of weight per day. For example, if your weight is 60 kilograms, then you need to eat 60 - 70 grams of fat per day.

2. Try to avoid foods high in saturated fats: fatty meats, sausages, fatty dairy products.

3. Reduce the amount of vegetable oils containing Omega-6: sunflower, corn, peanut.

4. Add omega-6 oils to your diet: canola, linseed, hemp, soybean and mustard.

5. Try to eat less fried foods. Use only refined oils for frying. Give preference to olive oil.

6. Avoid Trans Fatty Acids

7. Be vigilant when buying sweets for children. Almost all confectionery products (chocolate bars, waffles, cookies, ice cream, and so on) contain margarine (hydrogenated vegetable oil), which adversely affects children's health.
The role of unsaturated fatty acids that make up fats

Fats are a combination of glycerol and various fatty acids. The function and value of dietary fat depends on the fatty acids that are included in its composition.

Polyunsaturated fatty acids: linoleic, linolenic and arachidonic - are essential nutritional factors, since they are not synthesized in the body and therefore must be supplied with food. These acids, according to their biological properties, are vital substances and are even considered as vitamins (vitamin F).

The physiological role and biological significance of these acids is diverse. The most important biological properties of unsaturated acids are their participation as structural elements in such highly active complexes as phospholipids, lipoproteins and others. They are a necessary element in the formation of cell membranes, connective tissue and others.

Arachidonic acid precedes the formation of substances involved in the regulation of many life processes of platelets and prostaglandins, which are of great importance as substances of the highest biological activity. Prostaglandins have a hormone-like effect, which is why they are called "tissue hormones", since they are synthesized directly from membrane phospholipids. The synthesis of prostaglandins depends on the provision of these acids by the body.

A link has been established between unsaturated fatty acids and cholesterol metabolism. They contribute to the rapid conversion of cholesterol into folic acids and remove them from the body.

Unsaturated fatty acids have a normalizing effect on the walls of blood vessels, increase their elasticity and reduce permeability.

The relationship of unsaturated fatty acids with the metabolism of B vitamins has been established.

With a deficiency of unsaturated fatty acids, the intensity and resistance to adverse external and internal factors decrease, reproductive function is inhibited, the deficiency of unsaturated fatty acids affects myocardial contractility and causes skin damage.

Vegetable fats have a high energy state, as they are formed directly during photosynthesis in the green parts of plants and then deposited in fruits and seeds.

Walnut oil is a source of highly digestible emulsified fats. If you eat enough nuts, there is no need to add any oils to the diet.

It is desirable to use the oil obtained by cold pressing. Refined oil, devoid of trace elements and vitamins, should be excluded. In addition, acids in refined oil are easily oxidized and oxidized products accumulate in the oil, which lead to its deterioration.

Animal fats contain toxic inclusions, which, when broken down, enter the body. After all, adipose tissue of both animals and humans is a "sump", since it has the lowest metabolism. For this reason, the body, in order to get rid of toxins, deposits them in adipose tissue, where they are stored.
The role of fats in the brain

The main difference between humans and all other mammals is specific gravity brain relative to total weight. Indeed, ask any even the most uneducated person what is the difference between people and animals, and he will answer - a person has a brain and he knows how to think. But here's the trouble - to have something does not mean to be able to fully use it. This statement also applies to the brain - in order to use it to its full potential, it must be given the necessary nutrition.

According to medical research, human brain tissue is composed of about 60% fat. What is very important, fats that enter the body with food affect the functioning of the human brain. Eating unhealthy oils and fats can lead to various brain abnormalities.

Currently, scientists have established that under optimal conditions, Omega-3 fatty acids and Omega-6 should enter the body in equal proportions, which was observed in our ancestors. Now the ratio of these acids in food has changed to 20 and even 30: 1, that is, for 30 grams of Omega-6 there is only one gram of Omega-3. This situation has developed for several reasons.

Increased consumption of oils rich in Omega - 6 (sunflower, corn, sesame, and so on).
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Reduced consumption of oils rich in Omega - 3 (linseed, hemp, soybean, and so on).
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During production, the oils began to undergo a hydrogenation process - margarine is obtained, which does not contain Omega - 3.
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Fish of artificial cultivation appeared - with the help of special feeds.
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Due to the application modern ways processing, cereals began to lose their core (embryo), rich in healthy fats.

All these changes in eating habits have a very negative effect on the functioning of the brain. If one of the fatty acids begins to predominate first in the diet, and then in the brain, this leads to malfunctions. nervous system. If the brain does not receive enough fats it needs, then its structure begins to change, which leads to a number of deviations in the work of this organ and the whole organism. For example: aggression, autism, Parkinson's disease, hostility towards others, hyperactivity, depression, retinal diseases, mental and physical retardation, drug abuse, migraines, brain tumors, paralysis, multiple sclerosis.

As we can see, by supplying the body with the right fats, we take care not only about gastrointestinal tract but also about the full functioning of the brain and the health of the whole organism.

The effect of fats on the children's and youthful body

During growth and development, the body reacts most strongly (in the form of various diseases) to the negative factors of the surrounding world. As we have already determined, fat is different for fat, and what fats enter the body of a child and adolescent directly depends on his health, both mental and physical. The biggest harm is caused by trans fatty acids, which easily enter the body if it is not controlled - literally with mother's milk. Research results show that on average, a woman's milk contains about 20% of trans fatty acids from the total amount of fatty acids. Basically, trans fatty acids enter the body of a woman with food, and then penetrate into breast milk. The trouble is that in parallel with the increase in trans fats in the body of a woman and a child, the amount of essential, beneficial fatty acids, such as Omega-3, decreases.

What should be done to reduce the amount of incoming trans fats in the child's body.

Strictly monitor what foods a woman eats before conception, during pregnancy and during breastfeeding.
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Get enough antioxidants.
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Ensure that the body has the right balance of Omega-3 fatty acids.

IN preschool age All responsibility for the future health of children lies with the parents. They should carefully monitor their diet so that it contains a minimum of trans fats. At preschool age, the brain develops very rapidly, and if the child receives high-quality fats, this will not only have a positive effect on his health, but also on his mental abilities.

Children school age and teenagers are the most active consumers of trans fats. In one donut alone, they can contain up to 13 grams. A standard pack of chips contains 7-8 grams of trans fatty acids. There are 8 grams of trans fatty acids in 100 grams of french fries. As a result, it turns out that a teenager eats 30-50 grams of bad fats per day. And this happens at a time when the brain is developing most actively and nerve cells must constantly form many new connections.

The basic rules that must be followed to facilitate the absorption of fats by the body.

1. The body does not absorb fats from highly fatty foods: pork, chicken legs, cakes, pastries. Therefore, this food should not dominate the diet.

2. It is necessary to constantly maintain the work of the liver and gallbladder.

3. Do not drink food with water and other drinks. Such a habit, on the one hand, dilutes the digestive juice, and on the other hand, washes food into other parts of the intestine, where the breakdown of fats is not so effective.

The role of fats in the body

Our body needs fats not only to be deposited on the waist and hips. Fats are the most important nutrient, and when they are deficient in food, serious health problems arise.

1. Fats are essential for the formation of cell membranes and connective tissue.

2. Adipose tissue is a support for internal organs (heart, liver, kidneys), and with excessive thinness, the organs are displaced and their activity is disrupted.

3. Components of fats (unsaturated fatty acids) contribute to the removal of excess cholesterol from the body.

4. Fats increase the elasticity and permeability of the walls of blood vessels.

6. Lack of fat in the diet worsens the work of the heart muscle, negatively affects the condition of the skin.

7. Fats are involved in the synthesis of hormones - substances that the body constantly needs for normal functioning.

Fat fat - strife, and not a friend.

This could be the end of the story about fats, but in real life not everything is so simple and smooth. Fats that enter the body with food can have different properties and incompletely fulfill the functions assigned to them by nature. The properties of fat depend primarily on what fatty acids are included in its composition. Varieties of modern dietary fats.

1. Saturated fat - Composed of glycerol and saturated fatty acids, it usually has a solid consistency even at room temperature. The most common source of saturated fat is animal products. These fats are harmful to the body when there is a lot of them in food - they contribute to an increase in the level of cholesterol in the blood, the development of cardiovascular diseases. We must remember that saturated fats are not essential for humans, and can be synthesized from other substances.

2. Unsaturated fats are found in vegetable oils, nuts and some types of marine fish. Unsaturated fats do not solidify at room temperature, even in a conventional refrigerator. The most famous ingredients unsaturated fat are Omega-3 and Omega-6 polyunsaturated fatty acids. Almost all the benefits that fats bring to the body can be written down as an asset to unsaturated fatty acids. What is very important: unsaturated fatty acids are not synthesized by the body, and products containing them must be present in the human diet: marine oily fish that lives in the northern seas, nuts, canola oil, walnut oil, linseed oil.

3. Trans fats are the worst fat that is harmful to the body in any concentration. It turns out after heating vegetable fats to high temperatures in the presence of hydrogen. Trans fats are widely used in semi-finished products, industrial sweets, fatty ketchups, and sauces.

As we can see, the key to health is a balanced attitude towards fatty foods: eliminate trans fats from your diet, minimize saturated fats, and consume unsaturated fats in reasonable amounts.

Most of the fats that we eat with food are used by our body or remain in reserve. In a normal state, only 5% of fats are excreted from our body, this is carried out with the help of sebaceous and sweat glands.

The regulation of fat metabolism in the body occurs under the guidance of the central nervous system. Our emotions have a very strong influence on fat metabolism. Under the influence of various strong emotions, substances enter the bloodstream that activate or slow down the fat metabolism in the body. For these reasons, one should eat in a calm state of mind.

Why are fats needed in the human body?

One of the most important is the energy function fat in the human body.

The amount of fat in the body of an average man is 10-15 kg, which is enough to sustain the body for 40-50 days. In women, this figure is higher and amounts to 15-20 kg.

What are the benefits of fats for the body

First of all, it is protection.

The surface of the human body is protected from injury and damage, as well as from hypothermia by a layer of subcutaneous fat. The most important internal organs, such as the kidneys, are surrounded by a fairly thick layer of fat that protects them from concussions and bruises.

The statement of biochemists at the University of California shows the role of oleoylethanolamide, a fatty acid that affects the feeling of human hunger. This molecule is part of many natural fats and when it is lacking, hunger is felt, and vice versa, a sufficient amount dulls the feeling of hunger, sometimes even at a clearly low level of calories.

Another important role of fats in the human body is its high resistance to infections and radiation.

The bottom line is that human fat cells produce cytokines - substances involved in the functioning of the immune system.

Scientists and doctors studying why the body needs fats show that people who refuse to consume fats reduce the level of useful forms of cholesterol in the blood. And this leads to atherosclerosis, increased irritability and depression, as well as to a decrease in mental abilities in childhood.

Long-term diets that sharply limit fats lead to hypovitaminosis.

Low libido, reduced sperm quality, infertility and impotence in men can be the result of a lack of healthy fats in the body.

After all, the male sex hormone testosterone, like many other hormonal substances, is formed from fats.

Therefore, it is worth figuring out what fats give to the human body, which of them are beneficial and which are harmful.

Types and properties of existing fats

All fats are made up of three types: simple, complex and derivatives.

Simple fats are called triglycerides (TG) - this is glycerol and three fatty acid molecules.

Triglycerides are the main mass of fat in the human body and make up at least 90% of the total fat mass. TG accumulate in adipose and muscle tissue, in fact, being a concentrated source of energy (1 g of fat contains 9 kcal, carbohydrates and proteins are half as high in calories), providing about 70% of the body's energy consumption.

Complex fats are called phospholipids, and derivatives are called cholesterol.

There are also unsaturated, polyunsaturated and saturated fatty acids. The former include sunflower, corn, olive, cottonseed, soybean, poultry, nuts and seeds. It is characteristic that the above vegetable oils fully retain their useful qualities even after heat treatment.

Polyunsaturated fatty acids are not produced by the body on their own, but are indispensable in the structure of nerve cells, they transport oxygen to all organs and tissues.

In symbiosis with protein and cholesterol, they represent cell membranes human body. They are found in fish and fish oils, linseed and rapeseed oils, walnut and wheat germ.

Animal fats are saturated fatty acids.

Protecting the skin from drying out, and the internal organs from injury and cold, fats also carry vitamins throughout the body. Reducing the amount of fat in the diet can lead to heart problems and other complications. Saturated fatty acids are found in meat, lard, milk fat, butter, palm and coconut oils, cocoa butter.

At temperatures below 18-20 degrees, these substances are in a solid state.

The body's need for fat

- In the daily diet, fats should be 30-40% of its calories.

That is, about a gram of fat per kilogram of body weight. Eating more fat is essential in cold climates, sports, and hard physical work.

- The ratio of vegetable and animal fats should be 2 to 1.

Vegetable fats, excluding coconut and palm oil, contain useful unsaturated fatty acids, vitamin E and practically do not contain cholesterol.

Fish and seafood should be consumed at least 2 times a week.

It is better to use fats that retain all the beneficial qualities that are part of natural products, such as seeds, nuts, avocados, olives.

Less preferred are unrefined and raw cold-pressed oils, butter. Even less useful are refined oils, hydrogenated fats, and butter substitute sandwiches.

The effect of fats on the body

Nature provides for the use of fats in the body as the main source of energy.

Adipose tissue is not completely consumed even during prolonged fasting or extreme overload. The amount of fat in men with proper nutrition is 15-20% of body weight, in women - up to 25%.

A higher percentage of fat leads to unpleasant side effects. Such people are less mobile, lethargic, their excess weight leads to overload of the joints, ligaments and tendons. In more severe cases, there are problems associated with the work of the heart, hypertension, atherosclerosis, diabetes and others.

The value of fats in the body is very high, since the survival of a person in the natural environment depends on them.

Lack of food during the off-season, poor harvests, and other natural disasters justified some excess fat.

In the modern civilized world, it makes no sense to accumulate excess energy, given the availability necessary products during a year.

In addition, do not forget about hypodynamia, that is, that a modern person does not move much, but consumes more calories than they consume.

The human body has a certain amount of fat cells, genetically determined. Excessive nutrition and an unhealthy lifestyle can lead to an increase in the volume of a fat cell by 900 times its original volume, and this just leads to an increase in the mass of the whole body with all the ensuing consequences.

Importance of fats in human nutrition

The role of fats in the body

Fats (lipids from the Greek lipos - fat) are among the main nutrients (macronutrients). The importance of fat in nutrition is manifold.

Fats in the body perform the following main functions:

energy - They are an important source of energy, surpassing all food substances in this regard.

When burning 1 g of fat, 9 kcal (37.7 kJ) are formed;

plastic - are a structural part of all cell membranes and tissues, including nervous;

are vitamin solvents A, D, E, K and contribute to their assimilation;

serve as suppliers of substances, with high biological activity: phosphatides (lecithin), polyunsaturated fatty acids (PUFAs), sterols, etc.;

protective - the subcutaneous fat layer protects a person from cooling, and the fats around the internal organs protect them from concussions;

taste - improve the taste of food;

cause feeling of prolonged satiety(feeling full).

Fats can be formed from carbohydrates and proteins, but they are not fully replaced.

Fats are classified into neutral (triglycerides) And fat-like substances (lipoids).

Biological effectiveness of fats

Neutral Fats consist of glycerine And fatty acids.

Fatty acids largely determine the properties of fats.

Biological efficiency- an indicator of the quality of food fats, reflecting the content of essential polyunsaturated fatty acids in them.

More than 200 fatty acids have been found in nature, but only 20 are of practical importance.

Fatty acids are classified into saturated, monounsaturated, polyunsaturated.

Saturated fatty acids (to the limit saturated with hydrogen - marginal) - palmitic, stearic, myristic, oily, caproic, caprylic, arachidic, etc.

IN macromolecular saturated fatty acids (stearic, arachidic, palmitic) have a solid consistency, low molecular weight(oil, kapron, etc.) - liquid. (most vegetable oils).

Solid fats are dominated by saturated fatty acids (fats of animals and birds). The more saturated fatty acids, the higher the melting point of fat, the longer it is digested and the worse it is absorbed (lamb and beef fats).

The biological activity of saturated fatty acids is low.

Saturated fatty acids are associated with ideas about their negative effect on fat metabolism, the development of atherosclerosis. There is evidence that an increase in blood cholesterol is associated with the intake of animal fats, which have saturated fatty acids in their composition. Excess intake of solid fats also contributes to the development coronary disease heart disease, obesity, gallstone disease, etc.

monounsaturated (monoenoic) - applies to them oleic acid, which is found in almost all fats of animal and vegetable origin.

A large amount of it is found in olive oil (66.9%). There is evidence of a beneficial effect of oleic acid on lipid metabolism, in particular on cholesterol metabolism and biliary tract function.

WHO (2002) classified oleic acid as a possible, but not completely proven, nutritional factor that reduces the risk of cardiovascular disease.

Polyunsaturated (polyene, polyunsaturated fatty acids) having two or more free double bonds.

These include linoleic acid with two double bonds linolenic, which has three double bonds, and arachidonic with four double bonds. These acids, due to their biological properties, are called vitamin F. Linoleic and linolenic acids are irreplaceable (essential) nutrients, tk.

are not synthesized in the body and come only with food.

PUFAs are involved in the regulation of metabolic processes in cell membranes, in the formation of energy in mitochondria. About 25% of the fatty acid composition of membranes is arachidonic acid. Tissue hormone-like substances (prostaglandins) are formed from PUFAs in the body, they have a positive effect on fat metabolism in the liver, increase the elasticity of blood vessels, normalize skin condition, and are necessary for the normal functioning of the brain.

PUFAs are able to bind cholesterol in the blood, form an insoluble complex with it and remove it from the body (anti-sclerotic role).

PUFA transformations in the body depend on the chemical structure, namely on the position of the first from the methyl end of the double bond. Yes, at linoleic acid, this bond is in position 6. All other acids (in particular arachidonic) formed from it also have the first double bond in position 6 and belong to PUFAs of the omega-6 family.

At linolenic acids, the first free double bond is the most remote and is located in position 3, therefore, this acid and its conversion products (eicosapentaenoic, docosapentaenoic and docosahexaenoic fatty acids) belong to PUFAs of the omega-3 family.

Vegetable oils (sunflower, corn, cottonseed and soybean) are very rich in linoleic acid.

A good source of linoleic acid are soft margarines, mayonnaise, nuts. Of the cereals, it is most in millet, but 25 times less than in sunflower oil.

table 2

The amount of fatty acids (in g) in 100 g of fatty foods.

Its highest content is in pork fat (2 g%) and butter (0.2-0.5 g%).

Sources of linolenic acid are linseed, hemp, soybean, mustard and rapeseed oils. The source of omega-3 PUFAs is mainly the fats of marine fish and animals (herring, salmon, cod liver, marine mammals, etc.).

It should be noted that in some products there are simultaneously significant amounts of linoleic and linolenic acids - hemp, soybean, mustard and rapeseed oils.

The physiological effects of PUFAs in the body are largely related to their metabolites.

Recent studies have shown that omega-3 family PUFAs normalize fat metabolism, increase the plasticity of blood vessels, reduce blood viscosity, prevent the formation of blood clots, stimulate the immune system (participate in the formation of T-lymphocytes), prostaglandin production, have antioxidant and anticarcinogenic effects.

Their positive role has been established in the treatment of atherosclerosis, coronary heart disease, hypertension, stomach ulcers, diabetes, allergic and skin diseases, etc.

In the diet of a healthy person, the ratio of PUFAs omega-6 to omega-3 should be 10:1, and in violation of lipid metabolism from 3:1 to 6:1.

A study of the actual nutrition of the population showed that in a significant part of the population this ratio ranges from 10:1 to 30:1. This indicates a deficiency of PUFAs of the omega-3 family.

5.3. Freshness of fats

The nutritional value of fats is determined not only by the fatty acid composition, melting point, etc., but also freshness indicators.

Freshness- a mandatory sign of the usefulness of fats.

Dietary fats during long-term storage in the presence of oxygen and light become rancid, which is associated with autoxidation unsaturated fatty acids. Prolonged heat treatment has a negative effect on fats. Vitamins are destroyed in oxidized and overheated fats, the content of PUFAs decreases and harmful substances (peroxides, aldehydes, etc.) accumulate, causing irritation of the gastrointestinal tract and disrupting metabolism.

In the human body, fats can also undergo autoxidation (lipid peroxidation). This process is referred to as free radical oxidation, which is actively initiated by primary oxygen radicals constantly arising in tissues.

The human body has antioxidant protection, in the absence of which a number of diseases develop, incl. atherosclerosis. TO antioxidants include enzymes (catalase, superoxide dismutase, etc.), uric acid, albumin, as well as a number of micronutrients (vitamins E, A and C, ß-carotene, selenium), etc.

To prevent autoxidation of fatty acids and rancidity of dietary fats, antioxidants are introduced into fat-containing products.

Trans-fatty acids (TIFA)

Trans-fatty acids special shapes of unsaturated fatty acid molecules, sometimes called "freak molecules". TIFAs are devoid of biological effectiveness and are only sources of energy for the body. However, when consumed in large quantities, they can adversely affect the body.

In natural milk and meat fats, soft margarines, TIFAs make up about 3% of all fats.

There are many TIFAs (up to 14%) in the hydrogenated fats produced by the fat industry, which are used for the production of hard margarines, cooking and confectionery fats. These fats are widely used in the confectionery industry for the manufacture of biscuits, sweets, chocolate spreads, potato chips, wafer layers, etc.

They are used when frying various culinary products (patties, chickens, etc.).

There is evidence that FAFAs, like saturated fatty acids, increase total cholesterol levels and reduce anti-atherogenic fractions in the blood.

This is a risk factor for the development of atherosclerosis, disrupts the metabolism of biologically active substances formed from polyunsaturated fatty acids, and worsens the quality of fats. breast milk in nursing mothers. It should be noted that we are not talking about the dangers of consuming fat-containing waffles or potato chips, but that these and similar products should not be abused in the daily diet of a healthy person.

Fat-like substances

are of great value to the organism. fatty substances (lipoids). These include biologically active substances - phospholipids And sterols.

Phospholipids (phosphatides) - the main representatives are lecithin, cephalin and sphingomyelin.

In the human body, they are part of the cell membranes, are essential for their permeability, metabolism between cells and intracellular space.

Food phospholipids vary in chemical composition and biological action. The latter largely depends on the nature of the constituent amino alcohol.

Most widely found in food lecithin. Lecithin contains glycerin, unsaturated fatty acids, phosphorus and vitamin-like substance choline.

Lecithin has lipotropic action - reduces the accumulation of fats in the liver, facilitating their transport into the blood. It is part of the nervous and brain tissue, affects the activity of the nervous system. Lecithin is an important factor in the regulation of cholesterol metabolism. prevents the accumulation of excess amounts of cholesterol in the body, promotes its breakdown and excretion. Of great importance is a sufficient amount of lecithin in diets for atherosclerosis, liver disease, cholelithiasis, in the diets of individuals mental labor and the elderly, as well as in the diets of therapeutic and preventive nutrition.

The daily requirement for lecithin is about 5 g.

Eggs (3.4 g%), liver, caviar, rabbit meat, fatty herring, unrefined vegetable oils (2.5-3.5 g%) are rich in lecithin. Beef, lamb, pork, chicken meat, peas contain about 0.8 g% lecithin, most fish, cheese, butter, oatmeal - 0.4-0.5 g%, fat cottage cheese, sour cream - 0, 2 g%. A good source of lecithin for low fat content is buttermilk.

Sterols are hydroaromatic alcohols of a complex structure contained in vegetable oils (phytosterols) and animal fats (zoosterols).

Of the phytosterols, the most famous ß-sitosterol Most of it is found in vegetable oils. It normalizes cholesterol metabolism, forming insoluble complexes with cholesterol, which prevent the absorption of cholesterol in the gastrointestinal tract, and thereby reduce its content in the blood.

Cholesterol refers to animal sterols.

It is a normal structural component of all cells and tissues. Cholesterol is part of cell membranes and, together with phospholipids and proteins, provides selective permeability of membranes and affects the activity of enzymes associated with them. Cholesterol is a source of formation of bile acids, steroid hormones of the sex glands and the adrenal cortex (testosterone, cortisone, estradiol, etc.), vitamin D.

It should be highlighted association of dietary cholesterol with atherosclerosis, the causes of which are complex and diverse.

It is known that cholesterol is a part of complex plasma proteins. lipoproteins. There are high density lipoproteins (HDL), low density lipoproteins (LDL) and very low density lipoproteins (VLDL). TO atherogenic, those. contributing to the formation of atherosclerosis, include LDL and VLDL. They are able to be deposited on the vascular wall and form atherosclerotic plaques, as a result of which the lumen of the blood vessels narrows, the blood supply to the tissues is disturbed, the vascular wall becomes fragile and fragile.

The main part of cholesterol in the body is formed in the liver (about 70%) from fatty acids, mainly saturated ones.

Part of the cholesterol (about 30%) a person receives from food.

The qualitative and quantitative composition of food significantly affects the metabolism of cholesterol.

The more cholesterol comes from food, the less it is synthesized in the liver and vice versa. With the predominance of saturated fatty acids and easily digestible carbohydrates, cholesterol biosynthesis in the liver increases, and in the case of the predominance of PUFAs, it decreases. Cholesterol metabolism is normalized by lecithin, methionine, vitamins C, B6, B12, etc., as well as trace elements.

In many products, these substances are well balanced with cholesterol: cottage cheese, eggs, sea ​​fish, some seafood. Therefore, individual products and the entire diet should be evaluated not only by the cholesterol content, but also by the combination of many indicators. Currently, animal saturated fatty acids and hydrogenated fats are considered to be more significant risk factors for the development of cardiovascular disease than dietary cholesterol.

Cholesterol is widely present in all food products of animal origin (Table 1).

A normal daily diet should contain no more than 300 mg of cholesterol. During heat treatment, about 20% of cholesterol is destroyed.

Table 3

Sources of fats in the diet

None of the dietary fats, taken separately, can fully meet the body's needs for them. So , animal fats, including milk fat, have high palatability, contain quite a lot of vitamins A and D, lecithin, which has lipotropic properties.

However, they are low in PUFAs and high in cholesterol, one of the risk factors for atherosclerosis.

Vegetable fats contain a lot of PUFAs, vitamin E and ß-sitosterol, which contributes to the normalization of cholesterol metabolism.

At the same time, vitamins A and D are absent in vegetable oils, and during heat treatment, these oils are easily oxidized.

Sources of animal fats are pork fat (90-92% fat), butter (62-82%), fatty pork (49%), sausages (20-40%), sour cream (10-30%), cheeses (15- 45%), etc.

Sources of vegetable fats - vegetable oils (99.9% fat), nuts (53-65%), oatmeal (6.1%), buckwheat, millet (3.3%), etc.

IN healthy eating a combination of animal and vegetable fats should be provided.

Low calorie fat substitutes

Widespread overweight and obesity among the population economically developed countries called for the search and development of low-calorie fat substitutes, and also drew attention to low-fat "light" products.

There are two groups of fat substitutes.

First group includes carbohydrates and proteins, the molecules of which are modified in such a way that they are able to bind large amounts of water, three times the mass of these substances.

Swollen particles give a feeling of fat when chewed, and the calorie content of these substitutes is reduced to 1-2 kcal/g. From carbohydrates, low molecular weight starches, dextrins, maltodextrins and gums are used for such purposes. Protein fat substitutes are obtained from milk and eggs. Substitutes in this group are absorbed and metabolized like normal proteins and carbohydrates.

Second group substitutes is a synthetic substance that has the physical and technological properties of fats in food products.

Synthetic fat substitutes have different chemical nature, the degree of digestion and assimilation, as well as uneven effects on the gastrointestinal tract.

They replace fat in food in an equivalent weight ratio. Of the synthetic fat substitutes, the best known are esters of fatty acids with sugars, such as sucrose polyester. It should be emphasized that their safety and efficacy are being studied.

The need and rationing of fats in the diet

Fat rationing in the diet is made taking into account age, gender, nature of work, national and climatic characteristics.

According to Russian nutritional standards, a healthy adult needs an average of 1.1 g of fat per 1 kg of body weight. Of the total amount of fat consumed, about 30% should be vegetable.

The average daily physiological human need for saturated fatty acids is 25 g, PUFA - 11 g.

The best ratio of fatty acids is considered to be: 10-20% polyunsaturated, 30% saturated and 50-60% monounsaturated fatty acids.

Fat should provide about 30% of the daily energy value of the diet.

The need for fats in the Far North, due to an increase in heat production, is increased by 5-7%, in the conditions of the south it is reduced by 5% of the total energy value of the diet. In high mountainous areas, fat intake is limited, tk. due to a decrease in the oxygen content in the air at a reduced barometric pressure, the oxidation of fats in the body worsens and underoxidized products of fat metabolism accumulate.

Fats or lipids are among the main nutrients and are important components of nutrition. Fats are divided into neutral (triglycerides) and fat-like substances (lipoids). Neutral fats are made up of glycerin and fatty acids.

Lipoids: these include biologically active substances - phospholipids (they have a high biological activity, are not a significant source of energy and do not belong to essential nutritional components; lecithin, cephalin) and sterols (water-insoluble hydroaromatic alcohols of a complex structure and are divided into phytosterols and zoosterols ).

Fats in the human body perform the following main functions:

They serve as an important source of energy, surpassing all nutrients in this regard; when 1 g of fat is oxidized, 9 kcal (37.7 kJ) is formed;

Included in cells and tissues

They are solvents of vitamins A, D, E, K

They supply biologically active substances - PUFAs (polysaturated fatty acids: linoleic, linolenic, arachidonic acids), phosphates, sterols, etc.

They create protective and thermal insulation covers - the subcutaneous fat layer protects a person from hypothermia;

Improve the taste of food;

Cause a feeling of prolonged satiety.

Fats can be formed from B and U, but they cannot be fully replaced by them.

Fat metabolism: Fats and lipoids (phosphotides, sterols, cerebrisides) are insoluble in water, but soluble in organic solvents.

Used for plastic and energy metabolism.

The plastic role of fats is that they are part of cell membranes, but unlike B, only a small part of fats is part of cellular structures. The vast majority of F in the body is located in adipose tissue, the importance of F in energy metabolism is high.

Total number of women V The human body ranges from 10 to 20%.

But in pathological conditions (obesity), the amount of F is 40-50%.

The amount of spare F depends on: the nature of nutrition, the amount of food, on the constitutional characteristics of a person, on the amount of energy consumption during muscle activity, gender, age.

The amount of protoplasmic F (participating in the exchange of v-v) is stable and constant.

The formation and breakdown of fats in the body: F, absorbed in the intestines, enters the lymph and in a small amount into the circulatory system.

With abundant and long-term nutrition, any one type of F can change the composition of F deposited in the body.

With abundant carbohydrate nutrition and the absence of F in the diet, the body can synthesize F from W. Some unsaturated fatty acids (linoleic, linolenic, arachidonic) are indispensable. The process of regulation of fat metabolism, also by the nervous and endocrine systems, as well as tissue mechanisms, is closely related to carbohydrate metabolism. The breakdown of triglycerides occurs when the concentration of glucose in the blood decreases and vice versa.

That is, the relationship between fat and carbohydrate metabolism provides energy requirement organism.

With an excess of Y, triglycerides are deposited in adipose tissue, and with a shortage of Y, triglycerides are cleaved.

Many people are completely illiterate about the benefits and harms of various dietary fats. By completely eliminating the use of fat from the diet, you can get vitamin deficiency, spoil the condition of the skin and hair, and also cause serious harm to the hormonal system. In everything you need a reasonable approach, and especially in nutrition. Of course, the passion for refractory fats is unlikely to benefit the body, but, for comparison, in hot countries and northern latitudes, people need different amounts of fat in their diet.

The influence of fats on the human body is invaluable. Fats serve as a conductor of energy, participate in the synthesis of brain neurons, the immune system, increase the production of bile during digestion, and also help in the absorption of certain vitamins. Let's look at what fats are and how harmful or useful they are?

Saturated fats increase the level of “wrong” cholesterol in the blood, forming plaques in the vessels that threaten the development of atherosclerosis. Because of these fats, body weight changes and the risk of heart disease, the development of hypertension and ischemia increases. Purely outwardly, such fats are easy to identify: they retain their hardness both in cold and in heat. Fat on meat, butter, sausages, cream, lard are all saturated fats. Another percentage of such fats is present in palm, coconut oils, processed cheeses, semi-finished products.

trans fats

Very harmful, and pose a particular threat, as they have gained popularity in the manufacture of many products. These fats are cheaper than natural ones, and they are added wherever possible. In addition, trans fats increase the shelf life of products, which, in fact, explains their popularity among manufacturers of various products. These are cupcakes, cakes, cookies, crackers. semi-finished products for heating in the microwave. They also negatively affect blood vessels, and increase cholesterol levels.

Polyunsaturated fats

This type of fat group has useful properties. Firstly, there was a decrease in bad cholesterol and an increase in good cholesterol, which is beneficial for the health and condition of blood vessels in general. Fats of this type do not turn into plaques, allowing the blood flow to move freely along the vascular trajectory. The most valuable fats of this type are linseed, soybean, sunflower, corn oils, as well as seeds and nuts. As a kind of polyunsaturated fats - Omega-3 is found in fatty fish: mackerel, herring, salmon and fish oil itself.

In countries located near the sea, people are less likely to suffer from heart ailments, because olive oil is regularly present in their diet. It contains a rare type of fat, which not only stabilizes cholesterol levels, but also increases the content of "good" - the right cholesterol. Olive oil first pressing - a valuable product with a sufficient content of monounsaturated fats. More than 70% of these fats are present in olive oil. There are also plenty of these unique fats in avocados, peanuts, pistachios, cashews, and pecans.

As you can see, unsaturated vegetable fats are almost always healthy and contain a large number of useful components, so we recommend that you include as many foods as possible containing this type of fat in your diet. And at the same time, you need to limit the consumption of animal fats, try to eat less sweets and convenience foods, and your health will always be in order.

It is customary to call fats a group of simple lipids that can be utilized by the human body and have common structural features. Fats, some lipids, their constituents are responsible for many processes of normal human life.

Functions of fats in the body

Physiology, medicine, biochemistry are intensively developing in parallel with the emergence of new instrumental research capabilities. Additional scientific data are constantly appearing, taking into account which the main functions of fats in the body can be represented in the proposed set.

• Energy. As a result of oxidative breakdown, 9 kcal of energy is indirectly formed from 1 gram of fat, which significantly exceeds the same figures for carbohydrates.

• Regulatory. It has been established that as a result of metabolic reactions, 1 g of fat in the body synthesizes 10 g of "internal" water, which is more correctly called endogenous. The water that we get with food and drinks is called "external", exogenous. Water is an interesting substance that tends to unite in groups - associates. This distinguishes the characteristics of water that has undergone melting, purification, and boiling. Similarly, the qualities of water synthesized in the body and received from outside differ. Endogenous water must be synthesized, although its role has not yet been finally established.

• Structural plastic. Fats, alone or in combination with proteins, carbohydrates, are involved in the formation of tissues. Critical importance has a layer of cell membranes, consisting of lipoproteins - structural formations of lipids and proteins. The normal state of the lipid layer of the cell membrane ensures the metabolism and energy. So the structural and plastic functions of fats in the cell are integrated with the transport function.

• Protective. The subcutaneous layer of fat performs a heat-preserving function, protects the body from hypothermia. This is clearly seen in the example of children swimming in the cool sea. Toddlers with a slight layer subcutaneous fat freeze very quickly. Children with normal body fat can take water treatments for much longer. natural fat layer internal organs protects them to some extent from mechanical influences. A small fat layer normally covers many organs.

• Providing. Natural fats are always mixtures containing additional biologically active substances. The role of fats in the body lies in the parallel provision of components important for physiology: vitamins, vitamin-like compounds, sterols, and some complex lipids.

• Cosmetic and hygienic. A thin layer of fats present on the skin gives it firmness, elasticity, and protects against cracking. The integrity of the skin, which does not contain microcracks, excludes the ingress of microbes.

Composition of fats

Fats are a group of substances consisting of one or more esters of high molecular weight carboxylic acids and an alcohol - glycerol. Acids containing more than 4 carbon atoms are called higher fatty acids. The composition of fats varies depending on the source of excretion. In addition to these esters, natural fats may contain a small amount of free macromolecular acids, flavoring substances, pigments.

According to the structural features of acid residues, the entire group is usually divided into saturated and unsaturated fats.

• In saturated fats, all carbon atoms in the acid residue are linked to each other only by single bonds. The smallest saturated acid found in fats is called butyric acid. During long-term storage, the ester bond can be destroyed, acids are released. Free butyric acid has a pungent odor and a bitter taste. This is one of the reasons for the deterioration of the quality of fat during long-term storage.

Important! Saturated higher carboxylic acids predominate mainly in animal fats.

The most common in natural fats are acids with a greater number of carbon atoms and a mass of molecules than butyric acid, for example, palmitic, stearic. Palmitic was first isolated from palm oil, its content in which reaches 50%. Stearic acid was first extracted from the fat of pigs, the name of which in Greek became the basis for the name of the acid. All saturated acids are poorly soluble in water, which complicates the performance of the functions of fats in the cell.

• Unsaturated fats are esters with a significant content of unsaturated high molecular weight acids.: oleic, linoleic, linolenic, arachidonic. The term "unsaturated" is due to the presence between carbon atoms in such molecules not single, but double bonds. In ordinary language, we can say that such substances are not completely saturated with hydrogen. For ordinary consumers, it is not the structural features that are important, but the properties derived from them.

Important! All unsaturated fats are found mainly in plants, have low temperatures melting.

Under normal room conditions, they are in a liquid state. Unsaturated acids are usually divided into groups: oleic acid and structurally similar, linoleic acid and the like, linolenic acid with homologues, arachidonic acid. The last three groups have more than one double bond per molecule. Therefore, they are called polyunsaturated (PUFA). The name of this complex of acids, vitamin F, is considered obsolete. Nowadays, linolenic acids are often called omega-3 acids, and linoleic and arachidonic acids are often called omega-6 acids.

Physiological role of polyunsaturated fatty acids

• The structural function is to form cell membranes.

• The plastic role is performed in the formation of connective tissue, the surface of nerve fibers.

• Antisclerotic function is reduced to the ability to remove excess cholesterol from the cavity of blood vessels. Fats and cholesterol must enter the body in a strictly defined ratio. Excess cholesterol coming from outside, in combination with synthesized inside the body, can provoke vascular changes.

• PUFAs increase the protective resources of the body in relation to external influences, such as viruses, microbes, adverse environmental factors.

• For the normal functioning of the cardiovascular system, it is important to have physiological indicators of blood clotting. PUFAs contribute to the normalization of coagulability, which tends to increase with age.

• There is information in the scientific literature about the ability of PUFAs to break down certain types of malignant cells.

• From arachidonic acid, with the participation of enzymes, prostaglandins are formed, which are classified as hormones and hormone-like substances. Prostaglandins have a diverse regulatory effect, in particular, they indirectly improve the breakdown of fats in the body.

PUFAs are indispensable and should be included in the daily diet.

Sources of vegetable and animal fats

All food products are derived from animals and plants. Fats are no exception. More than 600 examples of various fats are currently known. The prevailing (more than 400) amount is plant matter. 80 species are animal fats, more than 100 species are fats of water inhabitants. Sources of fats of vegetable and animal origin are diverse, to a large extent determined by culinary traditions, place of residence, climate, income level of the population.

• Part of the fat is visible visually. These are butter and vegetable oils, lard, animal fats in the composition of meat, margarines.
• Some food fats are invisible. They are evenly distributed in meat, confectionery, dairy products, bread, fish, cereals, nuts.

How much fat do you need per day?

The needs of each person should be determined taking into account many circumstances: age, type of activity, area of ​​​​residence, type of constitution. When playing sports, it is advisable to get advice from a specialist who can take into account all individual characteristics. It is important to remember that animal fats and cholesterol come with food in parallel, make a diet taking into account all the components.

The answer to the question "How much fat should each person consume per day?" can be represented as the following list:

• the total amount of all fats -80-100 gr;
• vegetable oils - 25-30 gr;
• PUFA - 2-6 gr;
• cholesterol - 1 g;
• phospholipids - 5 gr.

In general, the fat content in the daily diet should be about 30%. Residents of the northern regions can increase the fat content in their daily diet up to 40%.

The maximum amount of fat is found in refined vegetable oils (up to 99.8%), in butter - up to 92.5% fat, in margarines - up to 82%.

• It must be remembered that one of the methods for obtaining margarines is to saturate vegetable oils with hydrogen. The process is called hydrogenation. In this case, isomers are obtained in the product that have a negative physiological effect - trans-isomers. Recently, a different method of producing margarine has been used - the modification of vegetable oils. Harmful isomers are not formed. Margarine was originally invented in France in the late 19th century to feed the poor and the military. If possible, margarine should be excluded from the diet.

In dairy products, the fat content can reach 30%, in cereals - 6%, in hard cheeses - 50%.

Given the importance of PUFAs, one should be aware of the sources of their content.

• The maximum amount of essential acids, primarily arachidonic, is found in fish fat. The ideal supplier of this acid is fish liver.
• Many PUFAs are found in vegetable oils. The content of linoleic acid in corn oil reaches 56%, in sunflower oil - 46%.
• The specific gravity of PUFA does not exceed 22% in lard, chicken, goose fat. Olive oil contains 15% essential acids.
• In butter, most animal fats, in milk fats, PUFAs are low, up to 6%.

In the list of mandatory components of natural fats recommended for daily nutrition, there is cholesterol. We get the right amount by eating eggs, butter, offal. They should not be abused.

Phospholipids, which are complex lipids, must be present in food. They contribute to the transportation of fat breakdown products in the body, their effective utilization, prevent fatty degeneration of liver cells, and normalize metabolism in general. Phospholipids are found in large quantities in the yolk of eggs, liver, milk cream, sour cream.

Excess fat in food

With an excess of fat in the daily diet, all metabolic processes are deformed. An excess of fat in food leads to the predominance of accumulation processes over cleavage reactions. There is a fatty degeneration of cells. They cannot perform physiological functions, which provokes numerous disorders.

Lack of fat in food

If there is little fat, the energy supply of the body is disrupted. Some part can be synthesized from the remains of molecules formed during the utilization of proteins and carbohydrates. Essential acids cannot be formed in the body. Consequently, all the functions of these acids are not realized. This leads to a breakdown, a decrease in resistance, a violation of cholesterol metabolism, and hormonal imbalance. An absolute lack of fat in the diet is rare. The lack of useful components of fat can manifest itself when the rules for combining dietary fats are not followed.