What fats provide in the cell. Functions of fats. Types and properties of existing fats

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, and their constituent parts are responsible for many processes of normal human life. The functions of fats in the human body are very important

Functions of fats in the human body

Physiology, medicine, biochemistry are intensively developing in parallel with the emergence of new instrumental research capabilities. Additional scientific data are constantly emerging, 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 from 1 gram of fat, 9 kcal of energy is indirectly formed, which is significantly higher than the analogous figures for proteins and 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 into groups - associates. This is the difference in the characteristics of water that has undergone melting, purification, boiling. Similarly, the quality of water synthesized in the body and received from the outside differ. Endogenous water must be synthesized without fail, although its role has not yet been finally established.

• Structural-plastic... Fats, alone or in combination with proteins, carbohydrates, participate in the formation of tissues. The most important is the 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 metabolism and energy. So the structural and plastic function of fats in the cell is 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. Babies with a small layer of subcutaneous fat freeze very quickly. Children with normal body fat can take water treatments for much longer. The natural fatty layer on the internal organs protects them to some extent from mechanical stress. A small layer of fat normally covers many organs.

• Providing... Natural fats are always mixtures containing additional biologically active substances. The role of fats in the body consists 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 fat 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 usually 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 high molecular weight acids, aromatics, 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. With prolonged storage, the ester bond can be destroyed, acids are released. Free butyric acid has a pungent odor, 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 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 acid was first isolated from palm oil, its content in which reaches 50%. Stearic acid was first extracted from pig lard, 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 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 of double bonds between the carbon atoms in such molecules. 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 originating from them.

Important! All unsaturated fats are found mainly in plants and have low melting points.

Under normal room conditions, they are in a liquid state. Unsaturated acids are usually subdivided 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 in the molecule. Therefore, they are called polyunsaturated (PUFA). The name of this complex of acids, vitamin F, is considered obsolete. Now, acids of the linolenic type are often called omega-3, such as linoleic and arachidonic - omega-6 acids.

• The structural function is to form cell membranes.

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

• Anti-sclerotic function is reduced to the ability to remove excess cholesterol from the blood vessel cavity. Fats and cholesterol must enter the body in a strictly defined ratio. Excess cholesterol coming from the outside, in conjunction with that synthesized inside the body, can provoke vascular changes.

• PUFAs increase the body's protective resources in relation to external influences, for example, 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.

• In the scientific literature there is information about the ability of PUFAs to break down some types of malignant cells.

• From arachidonic acid, with the participation of enzymes, prostaglandins are formed, which are referred to 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 irreplaceable and should be included in the daily diet.

Sources of vegetable and animal fats

All food products are obtained from animals and plants. Fats are no exception. More than 600 examples of different fats are currently known. The prevailing (more than 400) amount is plant substances. 80 species - animal fats, more than 100 species - fats of inhabitants of reservoirs. Sources of vegetable and animal fats are varied, to a great extent determined by culinary traditions, place of residence, climate, and the level of income of the population.

• Part of the fat is visible visually. These are butter and vegetable oils, lard, animal fats in meat, margarines.
• Some fats in foods 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 consult a specialist who can take into account all individual characteristics. It is important to remember that animal fats and cholesterol come in parallel with food, make up a diet taking into account all components.

The answer to the question "How much fat does each person need to absorb per day?" can be presented in the form of the following list:

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

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

• It must be remembered that one of the methods for producing 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 margarine production has been used - modification of vegetable oils. In this case, no harmful isomers are 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, remember the sources of their content.

• The maximum amount of essential acids, primarily arachidonic, is found in the fat of fish. The ideal supplier of this acid is fish liver.
• A lot of 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% of essential acids.
• In butter, most animal fats, in milk fats, PUFAs contain little, up to 6%.

Cholesterol is on the list of essential components of natural fats recommended for daily nutrition. 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 facilitate 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 fats in food leads to the predominance of accumulation processes over splitting reactions. Fatty degeneration of cells occurs. 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 residues 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 decline in strength, a decrease in resistance, a violation of cholesterol metabolism, and hormonal imbalance. An absolute lack of fat in food is rare. The lack of useful components of fat can manifest itself if the rules for combining dietary fats are not followed.

Alexey Dinulov, Elite - FPA Trainer

Post Views: 9 240

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

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

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

2. The membrane of all cells in the body is about 30% fat.

3. 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.

4. Fats deliver fat-soluble vitamins A, D, E and K.

From the above, we can conclude that various diets that sharply reduce the amount of fat entering the body with food, as well as the constant use of low-fat food products, are harmful to health and will not contribute to the health of the body.

Important facts about fats

1. Rates of fat consumption individually. It is recommended to eat 1 - 1.3 grams of fat per 1 kilogram of body 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 fat: fatty meats, sausages, fatty dairy products.

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

4. Add oils containing Omega-6 to the diet: canola, flaxseed, hemp, soy and mustard.

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

6. Try not to consume trans fatty acids.

7. Be careful when buying sweets for children. Almost all confectionery products (chocolate bars, waffles, cookies, ice cream, etc.) contain margarine (hydrogenated vegetable oil), which has a negative effect on children's health.

The role of fats in the brain

The main difference between humans and all other mammals is the large proportion of the brain in relation to the total weight. But the trouble is to have something, to 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, the fats that enter the body with food affect the functioning of the human brain. Eating unhealthy oils and fats can lead to various abnormalities in the brain.

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 or 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.

1. Increased consumption of oils rich in Omega-6 (sunflower, corn, sesame, and so on).

2. The consumption of oils rich in Omega-3 (flaxseed, hemp, soy and so on) has decreased.

3. During production, oils began to undergo a hydrogenation process - margarine is obtained, which does not contain Omega - 3.

4. Fish of artificial cultivation appeared - with the help of special feed.

5. Due to the use of modern processing methods, cereals began to lose their core (embryo), rich in healthy fats.

All of these changes in eating habits have a strong negative effect on the functioning of the brain. If one of the fatty acids begins to prevail first in the diet, and then in the brain, this leads to disturbances in the functioning of the nervous system. If the brain does not receive a sufficient amount of the 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 to 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 of the gastrointestinal tract, but also of the full functioning of the brain and the health of the whole organism.

The effect of fats on children and adolescents

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 - fat is different and on what fats enter the body of a child and adolescent, his health, both mental and physical, directly depends. The greatest harm is caused by trans fatty acids, which easily enter the body if it is not controlled - literally with breast milk.

Research results show that, on average, a woman's milk contains about 20% trans fatty acids of the total fatty acids. Basically, trans fatty acids enter a woman's body 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, for example, Omega-3, decreases.

What should be done to reduce the amount of trans fats entering the child's body?

Strictly monitor what foods a woman eats before conception, during pregnancy and during breastfeeding.

Get enough antioxidants.

Ensure that the body has the correct balance of Omega-3 fatty acids.

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

School-aged children and adolescents are the most active consumers of trans fats. A donut alone can contain up to 13 grams. A standard packet of chips contains 7 to 8 grams of trans fatty acids. 100 grams of French fries contains 8 grams of trans fatty acids. 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 role of polyunsaturated fatty acids in baby food

In the first years of life, the regular intake of substances with food that the body cannot synthesize is of great importance for the growth of a healthy child. These ingredients include polyunsaturated fatty acids (PUFA).

The main functions of PUFA of classes Omega-3 and Omega-6 are participation in the formation of phospholipids of cell membranes and the synthesis of biologically active substances - tissue hormones: prostacyclins, prostaglandins, leukotrienes and thromboxanes. These substances play an active role in the regulation of the functions of the whole organism, especially the cardiovascular system.

Long-chain polyunsaturated fatty acids play a special role in the formation and functioning of the central nervous system and visual analyzer in the fetus and infants. It is known that the human brain is 60% fat. At the same time, at least 30% of the total amount of fats is accounted for by long-chain PUFAs. They are included as a structural component in the composition of cell membranes. The distribution of PUFAs in tissues varies significantly. For example, docosahexaenoic acid is found in large quantities in the membranes of photoreceptors, accounting for 50% of all fatty acids in the outer segment of rods, which is necessary for the highest photochemical activity of rhodopsin.

Of greatest practical interest are 2 classes of PUFA: Omega-3 and Omega-6. The key representative of omega-6 fatty acids is long-chain arachidonic acid, which is part of the phospholipids of the cell membranes of platelets of endothelial cells. Arachidonic acid makes up 20-25% of all fatty acids of phospholipids of cell and subcellular membranes.

Eicosapentaenoic and docosahexaenoic acids - representatives of the Omega-3 family of long-chain fatty acids, are also present in the composition of phospholipids, their amount is approximately 2-5%. Insufficient consumption and (or) a violation of the synthesis of these acids leads to a change in the fatty acid composition of lipids of biological membranes, causing a deviation of a number of indicators of their functional state (permeability, enzymatic activity, fluidity, etc.).

Long-chain Omega-3 polyunsaturated fatty acids ensure the normal development of the child's sensory, motor, behavioral and other functions. Docosahexaenoic acid, for example, is essential for the normal development of the nervous system and the visual analyzer of the fetus and newborn. With a high content of docosahexaenoic acid in the diet of a pregnant woman, there is an increase in its level both in blood plasma and in mother's milk.

This is probably why children of mothers who received docosahexaenoic acid during pregnancy and lactation have a higher visual acuity. Other, besides the influence on visual acuity, positive effects are also known. In particular, docosahexaenoic acid helps to improve the cognitive abilities of the child and reduces the incidence of bronchitis.

Since a person needs an intake of long-chain PUFAs from the outside with food, a deficiency of these fatty acids in the diet can lead to deviations in physical and neuropsychic development in the first year of life.

The possibility of using solid fat (lard) in the diet of patients with chronic pancreatitis during the period of remission

Most dietary recommendations for pancreatitis should help keep the pancreas as calm and less active as possible. These dietary recommendations should definitely be taken into account in patients with hypersecretory form of chronic pancreatitis. However, the use of such food for people with the most common hyposecretory form raises questions. The use of products that do not stimulate the pancreas and create "artificial rest" are unlikely to create conditions for the normalization of the organ. The situation is aggravated by the fact that in the treatment of chronic pancreatitis drugs are widely used to replace the functions of the pancreas - this contributes to its even greater atrophy.

Today, nutritionists recommend that in chronic pancreatitis, sharply reduce (60 - 70 grams per day) the consumption of fats with the maximum restriction of refractory fats. It is recommended to eat natural fats in the form of refined vegetable oil and butter.

Long-term adherence to such a diet leads to a deficiency of certain nutrients and can increase the secretory insufficiency of the pancreas, since the organ is in a state of "artificial functional calm" for a long time.

Patients who follow a strict diet lose the necessary body weight and observe a decrease in physical strength.

For these reasons, many modern nutritionists do not recommend completely excluding solid fats from their diet after an exacerbation of the disease. According to studies, after discharge from the hospital, patients with chronic pancreatitis who began to eat 50 grams of solid fat per day did not experience bouts of the disease for 3 to 12 months. People felt better, gained from 3 to 5 kg of weight and their physical and mental performance increased.

Pork lard has certain advantages over butter: high energy value (820 kcal versus 740 kcal per 100 grams of product), contains 2 times less cholesterol (95 mg versus 180 mg per 100 grams of product), contains 10 times more linoleic acid ( 8.5 g versus 0.84 g per 100 g of product) and at the same time contains arachidonic acid and vitamin B 1, which is practically absent in butter, has 2 times more lecithin phospholipids, which normalize the metabolism of fats in the body.

Thus, a strict ban on the use of solid fats of animal origin should be prescribed to patients with chronic pancreatitis only during an exacerbation.

Conclusion: the inclusion of a limited amount of solid fat (lard) in the diet of patients with chronic pancreatitis without disturbing the patency of the Wirsung duct and without exacerbation, contributes to a more balanced diet and does not cause an exacerbation of the disease.

The role of unsaturated fatty acids in fats

Fat is a combination of glycerin and various fatty acids. The function and importance of fat from food depends on those fatty acids that are included in its composition.

Polyunsaturated fatty acids: linoleic, linolenic and arachidonic - are indispensable nutrients, since they are not synthesized in the body and therefore must be supplied with food. According to their biological properties, these acids belong to 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 an essential element in the formation of cell membranes and connective tissue.

Arachidonic acid precedes the formation of substances involved in the regulation of many vital processes of platelets and prostaglandins, which scientists attach great importance to 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 supply of these acids by the body.

The connection of unsaturated fatty acids with cholesterol metabolism has been established. They contribute to the rapid conversion of cholesterol to folate and their excretion from the body.

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

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

With a deficiency of unsaturated fatty acids, the intensity and resistance to unfavorable external and internal factors decreases, reproductive function is inhibited, the deficiency of unsaturated fatty acids affects the contractility of the myocardium, 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 are deposited in fruits and seeds.

Nut oil is a source of highly digestible emulsified fats. If you eat enough nuts, you don't need to add any oils to your 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 impurities, which, when broken down, enter the body. After all, adipose tissue of both animals and humans is a "settler", since it has the least metabolism. For this reason, the body, in order to get rid of toxins, deposits them in adipose tissue, where they are stored.

Cardiovascular System and Omega-3 Polyunsaturated Fatty Acids

Interest in fish oil as a factor affecting the heart and blood vessels arose in the seventies of the last century after a study showed a low mortality rate from coronary heart disease (coronary heart disease) among the coastal Eskimo population of Greenland, which predominantly feeds on marine fish and marine animals.

It was found that the cardiovascular system of the Eskimos is not prone to atherosclerosis and coronary heart disease due to fish oil, which contains Omega-3 polyunsaturated fatty acids (eicosapentaenoic and docosahexaenoic).

Another interesting study was conducted over 23 years among Japanese people living in Honolulu (Hawaii, USA) and it was found that the negative effect of smoking on the heart (early development and more severe course of CHD) is leveled in people who regularly eat fish 2 or more times a week. ...

In another open-label study of 1015 patients with myocardial infarction, half of whom were recommended to increase their fish intake after 2 years, a 29% reduction in CHD mortality was found compared to the 2 group that did not receive fish.

A large study on the effects of fish oil on the heart and blood vessels was carried out in Italy in 2003. Half of the 11,323 patients with myocardial infarction received 1 gram of omega-3 polyunsaturated fatty acids for 3 - 5 years, the rest received standard treatment from their doctor. During this time, 1031 patients (9.1%) died. Already after 3 months from the beginning of observation in patients who took fish oil in addition to the usual treatment, fewer deaths were recorded than in the control group (1.1% versus 1.6%). By the end of the observation, the reliability of the difference in favor of the patients of the main group became even higher (8.4 versus 9.9). The risk of death in the main group decreased by 21%.

In 2003, the American Heart Association recommended taking 1 gram of Omega-3 polyunsaturated fatty acids in encapsulated fish oil to reduce the risk of sudden death.

Experimental studies have identified properties of fish oil that may be important in suppressing atherosclerosis and improving the cardiovascular system.

1. Strengthening the production of anti-inflammatory prostaglandins.

2. Decrease in the level of leukotriene B 4.

3. inhibition of the function of neutrophils and monocytes.

4. The use of fish oil in the form of a concentrate of omega-3 polyunsaturated fatty acids leads to a decrease in triglyceride levels by 21-79%

6. Fish oil moderately lowers blood pressure in hypertension and reduces the hypertensive response to norepinephrine administration.

7. The blood clotting time is lengthened, the aggregation ability of platelets decreases, the viscosity of whole blood decreases, the fluidity of the membrane and the erythrocytes themselves increases, which improves their permeability in the blood flow.

The positive effect of fish oil on the body is multifaceted, therefore it is used to treat autoimmune and immunological diseases - bronchial asthma, lupus erythematosus and atopic dermatitis. The anti-inflammatory effect of fish oil provides additional grounds for its use in atherosclerotic diseases for the purpose of treatment and prevention.

Additional articles with useful information

Fats in your diet are often remembered, since it is this nutritional ingredient that is responsible for many diseases. If the metabolism of fats is not disturbed in the body, then their presence in the diet will not harm even an elderly person.

Metabolism does not stop for a second and has a very complex regulation system, which can naturally malfunction. But often people are in a hurry to ascribe to themselves the diagnosis of metabolic disorders, confusing the true disease with regular violations of the regime and rules of healthy eating.

Under the general term lipids (fats) in science, all fat-like substances are combined. Fats are organic compounds with different internal structures, but similar properties. These substances are insoluble in water. But at the same time they dissolve well in other substances - chloroform, gasoline. Fats are very widespread in nature.

Fat Research

The structure of fats makes them an indispensable material for any living organism. The assumption that these substances have one latent acid was made back in the 17th century by the French scientist Claude Joseph Jorua. He found that the process of decomposition of soap with acid is accompanied by the release of a fatty mass. The scientist emphasized that this mass is not the original fat, since it differs from it in some properties.

The fact that glycerol is also included in the structure of lipids was first discovered by the Swedish scientist Karl Scheele. The entire composition of fats was determined by the French scientist Michel Chevrelle.

Classification

It is very difficult to classify fats in terms of composition and structure, since this category includes a large number of substances that differ in their structure. They combine only one feature - hydrophobicity. In relation to the process of hydrolysis, biologists divide lipids into two categories - saponifiable and unsaponifiable.

The first category includes a large number of steroid fats, which include cholesterol, as well as derivatives from it: steroid vitamins, hormones, and bile acids. Lipids, called simple and complex, fall into the category of saponifiable fats. Simple ones are those that are composed of alcohol as well as fatty acids. This group includes various types of wax, cholesterol esters and other substances. Complex fats contain, in addition to alcohol and fatty acids, other substances. This category includes phospholipids, sphingolipids and others.

There is also another classification. According to her, the first group of fats includes neutral fats, the second - fatty substances (lipoids). Complex fats of a trihydric alcohol, such as glycerol, or a number of other fatty acids with a similar structure are considered neutral.

Diversity in nature

Lipoids include those substances that are found in living organisms, regardless of their internal structure. Fat-like substances can dissolve in ether, chloroform, benzene, hot alcohol. In total, more than 200 different fatty acids have been found in nature. At the same time, no more than 20 types are widespread. They are contained both in animal organisms and in plants. Fats are one of the main groups of substances. They have a very high energy value - 37.7 kJ of energy is released from one gram of fat.

Functions

In many ways, the functions performed by fats depend on their type:

• Reserve energy. Subcutaneous fat substances are the main source of food for living beings during fasting. They also provide a source of nutrition for striated muscles, liver, kidneys.
• Structural. Fats are part of the intercellular membranes. Their main components are cholesterol and glycolipids.
• Signal. Lipids perform various receptor functions and are involved in interactions between cells.
• Protective. Subcutaneous fat is also a good insulating material for living organisms. It also provides protection for the internal organs.

The structure of fats

One molecule of any lipid consists of an alcohol residue - glycerol, as well as three residues of various fatty acids. Therefore, fats are otherwise called triglycerides. Glycerin is a colorless, odorless, viscous liquid. It is heavier than water, and therefore mixes easily with it. The melting point of glycerin is +17.9 o C. Almost all lipid categories include fatty acids. By chemical structure, fats are complex compounds that include triatomic glycerol, as well as high molecular weight fatty acids.

Properties

Lipids enter into any reactions that are characteristic of esters. However, they also have some characteristic features associated with their internal structure, as well as the presence of glycerin. By their structure, fats are also divided into two categories - saturated and unsaturated. Saturated ones do not contain double atomic bonds, unsaturated ones do. The former include substances such as stearic and palmitic acids. The unsaturated ones include, for example, oleic acid. In addition to various acids, the structure of fats also includes some fat-like substances - phosphatides and sterols. They are also more important for living organisms, as they are involved in the synthesis of hormones.

Most fats are fusible - in other words, they remain liquid at room temperature. Animal fats, on the other hand, remain solid at room temperature, since they contain a large amount of saturated fatty acids. For example, beef lard contains the following substances - glycerin, palmitic and stearic acids. Palmitic melts at 43 ° C, and stearic melts at 60 ° C.

The main subject in which students study the structure of fats is chemistry. Therefore, it is desirable for the student to know not only the set of those substances that are part of various lipids, but also to have an understanding of their properties. For example, fatty acids are the basis of vegetable fats. These are substances that get their name from the process of their release from lipids.

Lipids in the body

The chemical structure of fats is the remains of glycerin, which is readily soluble in water, as well as residues of fatty acids, which, on the contrary, are insoluble in water. If you put a drop of fat on the surface of the water, then the glycerin part will turn in its direction, and fatty acids will be located on top. This orientation is very important. A layer of fat, which is part of the cell walls of any living organism, prevents the cell from dissolving in water. Particularly important are substances called phospholipids.

Phospholipids in cells

They also contain fatty acids and glycerin. Phospholipids differ from other fat groups in that they also contain phosphoric acid residues. Phospholipids are one of the most important components of the cell walls. Also of great importance for a living organism are glycolipids - substances containing fats and carbohydrates. The structure and function of these substances allow them to carry out various functions in the nervous tissue. In particular, a large number of them are found in the tissues of the brain. Glycolipids are located on the outside of the plasma membranes of cells.

The structure of proteins, fats and carbohydrates

ATP, nucleic acids, as well as proteins, fats and carbohydrates are organic substances of the cell. They consist of macromolecules - large and complex molecules in their structure, containing, in turn, smaller and simpler particles. There are three types of nutrients found in nature - proteins, fats, and carbohydrates. They have a different structure. Despite the fact that each of these three types of substances belongs to carbon compounds, the same carbon atom can form different intra-atomic compounds. Carbohydrates are organic compounds made up of carbon, hydrogen, and oxygen.

Differences in functions

Not only the structure of carbohydrates and fats differs, but also their functions. Carbohydrates break down faster than other substances - and therefore they can generate more energy. Being in the body in large quantities, carbohydrates can be transformed into fats. Proteins do not lend themselves to such transformation. Their structure is much more complex than the structure of carbohydrates. The structure of carbohydrates and fats makes them the main source of energy for living organisms. Proteins, on the other hand, are those substances that are consumed as a building material for damaged cells in the body. No wonder they are called "proteins" - the word "protos" comes from the ancient Greek language and is translated as "the one who comes first."

Proteins are linear polymers containing amino acids linked by covalent bonds. To date, they are divided into two categories: fibrillar and globular. In the structure of the protein, a primary structure and a secondary one are distinguished.

The composition and structure of fats make them indispensable for the health of any living organism. In case of illness and loss of appetite, stored fat acts as an additional source of nutrition. It is one of the main sources of energy. However, eating too much fatty foods can impair the absorption of protein, magnesium, and calcium.

The use of fats

People have long learned to use these substances not only for nutrition, but also in everyday life. Fats have been used for lamps since the prehistoric era, they were used to lubricate runners with which ships were launched into the water.

These substances are widely used in modern industry. About a third of all fats produced are for technical purposes. The rest are intended for human consumption. Lipids are used in large quantities in the perfumery, cosmetics, and soap industries. Mostly vegetable oils are used in food - they are usually included in various food products, such as mayonnaise, chocolate, canned food. In the industrial sector, lipids are used for the production of various types of paints and medicines. Also, fish oil is added to drying oil.

Technical fat is usually obtained from food waste and is used for the production of soap and household products. It is also extracted from the subcutaneous fat of various marine animals. In pharmaceuticals, it is used for the production of vitamin A. It is especially abundant in the liver of cod fish, apricot and peach oils.

The main components of all living cells are proteins, fats, the functions and properties of these compounds ensure the vital activity of organisms living on our planet.

Fats are natural, complete esters of glycerol and fatty acids with one base. They belong to the lipid group. These compounds perform a number of important body functions and are an indispensable component in the human diet.

Classification

Fats, the structure and properties of which allow them to be used for food, are by their nature divided into animal and vegetable. The latter are called oils. Due to the high content of unsaturated fatty acids in them, they are in a liquid state of aggregation. The exception is palm oil.

According to the presence of certain acids, fats are divided into saturated (stearic, palmitic) and unsaturated (oleic, arachidonic, linolenic, palmitoleic, linoleic).

Structure

The structure of fats is a complex of triglycerides and lipoid substances. The latter are phospholipid compounds and sterols. Triglyceride is an ester compound of glycerol and fatty acid, the structure and characteristics of which determine the properties of fat.

The structure of the fat molecule in general is displayed by the formula:

CHˉO-CO-R ''

CH2-OˉCO-R '' ',

In which R is a fatty acid radical.

The composition and structure of fats have in their structure three unbranched radicals with an even number of carbon atoms. most often represented by stearic and palmitic, unsaturated - linoleic, oleic and linolenic.

Properties

Fats, the structure and properties of which are determined by the presence of saturated and unsaturated fatty acids, have physicochemical characteristics. They do not interact with water, but they decompose completely in organic solvents. They are saponified (hydrolyzed) if they are treated with steam, mineral acid or alkalis. During this reaction, fatty acids or their salts and glycerin are formed. Form an emulsion after vigorous shaking with water, an example of this is milk.

Fats have an energy value of approximately 9.1 kcal / g or 38 kJ / g. If we translate these values ​​into physical indicators, then the energy released at the consumption of 1 g of fat would be enough to lift a load weighing 3900 kg by 1 meter.

Fats, the structure of their molecules determines their main properties, have a high energy content when compared with carbohydrates or proteins. The complete oxidation of 1 g of fat with the release of water and carbon dioxide is accompanied by the production of energy twice the combustion of sugars. For the breakdown of fats, carbohydrates and oxygen are needed in a certain amount.

In humans and other mammals, fat is one of the most important energy suppliers. In order for them to be absorbed in the intestines, they must be emulsified with bile salts.

Functions

In the body of mammals, fats play an important role, the structure and functions of these compounds in organs and systems have different meanings:

In addition to these three main functions, fats have several private ones. These compounds support the vital activity of cells, for example, provide elasticity and a healthy appearance of the skin, improve brain function. Cell membrane formations and subcellular organelles retain their structure and function due to the participation of fats. Vitamins A, D, E and K can be absorbed only in their presence. Growth, development and reproductive function are also highly dependent on the presence of fat.

The body's need

About a third of the body's energy consumption is replenished by fats, the structure of which allows solving this problem with a properly organized diet. The calculation of the daily requirement takes into account the type of activity and age of the person. Therefore, most of all fats are needed by young people leading an active lifestyle, for example, athletes or men who are engaged in hard physical labor. With a sedentary lifestyle or a tendency to be overweight, their number should be reduced to avoid obesity and related problems.

It is also important to consider the structure of fats. The ratio of unsaturated and saturated acids is essential. The latter, with excessive consumption, disrupt fat metabolism, the functioning of the gastrointestinal tract, and increase the possibility of atherosclerosis. Unsaturated acids have the opposite effect: they restore normal metabolism, remove cholesterol. But their abuse leads to indigestion, the appearance of stones in the gallbladder and excretory tracts.

Sources of

Almost all foods contain fats, and their structure can vary. The exception is vegetables, fruits, alcoholic beverages, honey and some others. Products are classified into:

Also important is fat, which determines the presence of one or another acid. On this basis, they can be saturated, unsaturated and polyunsaturated. The former are found in meat products, lard, chocolate, ghee, palm, coconut and butter. Unsaturated acids are found in poultry, olives, cashews, peanuts, olive oil. Polyunsaturated - in walnuts, almonds, pecans, seeds, fish, as well as in sunflower, flaxseed, rapeseed, corn, cottonseed and soybean oil.

Formulation of the diet

The structural features of fats require a number of rules to be followed when drawing up a diet. Nutritionists recommend adhering to the following ratio:

• Monounsaturated - up to half of the total fat;
• Polyunsaturated - a quarter;
• Saturated - a quarter.

In this case, vegetable fats should make up about 40% of the diet, animal fats - 60-70%. Older people need to increase the number of the former to 60%.

Trans fats should be limited or eliminated from the diet as much as possible. They are widely used in the production of sauces, mayonnaise, and confectionery. Fats exposed to intense heating and oxidation are harmful. They can be found in french fries, chips, donuts, pies, etc. Of this list, the most dangerous are foods that were cooked in rancid or used oil many times.

Useful qualities

Fats, the structure of which provides about half of the total energy of the body, have many beneficial qualities:

• cholesterol promotes better carbohydrate metabolism and ensures the synthesis of vital compounds - under its influence steroid hormones of the adrenal glands are produced;
• about 30% of all heat in the human body is produced by tissue located in the neck and upper back;
• badger and dog fat are refractory, cure respiratory diseases, including tuberculous lesions of the lungs;
• phospholipid and glucolipid compounds are part of all tissues, are synthesized in the digestive organs and counteract the formation of cholesterol plaques, support the functioning of the liver;
• thanks to phosphatides and sterols, the constant composition of the cytoplasmic base of the cells of the nervous system is maintained and vitamin D is synthesized.

Thus, fats are an indispensable component in the human diet.

Excess and deficit

The fats, structure and function of these compounds are beneficial only when consumed in moderation. Their excess contributes to the development of obesity - a problem that is relevant for all developed countries. This disease leads to an increase in body weight, decreased mobility and a deterioration in well-being. The risk of developing atherosclerosis, cardiac ischemia, and hypertension increases. Obesity and its consequences more often than other diseases lead to death.

Fat deficiency in the diet contributes to the deterioration of the skin, slows down the growth and development of the child's body, disrupts the functioning of the reproductive system, interferes with the normal metabolism of cholesterol, provoking atherosclerosis, and impairs the functioning of the brain and the nervous system as a whole.

Proper planning of the diet, taking into account the body's needs for fats, will help to avoid many diseases and improve the quality of life. Their moderate consumption, without excess and deficit, is essential.

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

1. The body poorly assimilates 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 gall bladder.

3. Do not drink food with water or other drinks. Such a habit, on the one hand, dilutes the digestive juice, and on the other hand, it 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 fat not only to be deposited on the waist and hips. Fats are the most important nutrients, and when they are deficient, food causes serious health problems.

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

2. Adipose tissue is a support for the 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 elimination of excess cholesterol from the body.

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

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 to fat - strife, and not a friend.

One could put an end to this in the story of 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, first of all, on what fatty acids are included in its composition. Varieties of modern edible fats.

1. Saturated Fat - composed of glycerin and saturated fatty acids, it is usually firm even at room temperature. The source of saturated fat is most often animal products. These fats are harmful to the body when there is a lot of them in food - they contribute to an increase in blood cholesterol levels, the development of cardiovascular diseases. It must be remembered 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 normal refrigerator. The most famous ingredients in unsaturated fats are Omega-3 and Omega-6 polyunsaturated fatty acids. Almost all the benefits that fats bring to the body can be recorded 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 fatty fish that lives in the northern seas, nuts, canola oil, walnut oil, flaxseed oil.

3. Trans fats - this is 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 convenience foods, industrial sweets, fatty ketchups, and sauces.

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

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 fat is removed from our body, this is done with the help of the sebaceous and sweat glands.

The regulation of fat metabolism in the body takes place 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 take food in a calm state of consciousness.

What are fats for 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 support the body for 40-50 days. For women, this figure is higher and is 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 sufficiently thick layer of fat to protect them from concussions and bruises.

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

Another important role of fats in the human body is its high resistance to infection 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 what the body needs fats for show that people who refuse to eat fats have a decrease in the level of useful forms of cholesterol in the blood. And this leads to atherosclerosis, increased irritability and depression, as well as a decrease in mental abilities in childhood.

Long-term diets that severely restrict fat lead to vitamin deficiency.

Low libido, decreased sperm quality, infertility and impotence in men can be due to 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 worthwhile to figure 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 composed of three types: simple, complex and derivatives.

Simple fats called triglycerides (TGs) are glycerol and three fatty acid molecules.

Triglycerides are the main mass of fat in the human body and account for at least 90% of the total fat mass. TGs 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 the 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 oil, poultry, nuts and seeds. It is characteristic that the aforementioned vegetable oils fully retain their beneficial qualities even after heat treatment.

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

In symbiosis with protein and cholesterol, they represent the cell membranes of the human body. They are found in fish and fish oils, flaxseed and canola oil, walnut oil, and wheat germ.

Animal fats are saturated fatty acids.

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

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

The body's need for fats

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

That is, per kilogram of body weight, about a gram of fat. Consuming more fat is necessary in cold climates, when playing sports and in jobs involving hard physical labor.

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

Vegetable fats, with the exception of coconut and palm oil, contain healthy unsaturated fatty acids, vitamin E, and virtually no 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 found in natural products, such as seeds, nuts, avocados, olives.

Unrefined and crude cold-pressed oils and butter are less preferred. Even less useful are refined oils, hydrogenated fats, and sandwich butter substitutes.

Effects 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 with 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 overloading of joints, ligaments and tendons. In more severe cases, there are problems associated with the work of the heart, hypertension, atherosclerosis, diabetes mellitus and others.

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

Lack of food in the off-season, poor harvest and other natural disasters justified the presence of some excess fat.

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

In addition, do not forget about physical inactivity, that is, that a modern person moves little, and consumes more calories than they expend.

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

The importance of fats in human nutrition

The role of fat in the body

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

Fats in the body have the following main functions:

energy - are an important source of energy, superior in this regard to all nutrients.

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

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

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

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

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

gustatory - improve the taste of food;

cause feeling of prolonged satiety(feeling of satiety).

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

Fats are subdivided into neutral (triglycerides) and fatty substances (lipoids).

Biological effectiveness of fats

Neutral fats consist of glycerin and fatty acids.

Fatty acids largely determine the properties of fats.

Biological effectiveness- an indicator of the quality of fats in food products, 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 (saturated with hydrogen to the limit - limit) - palmitic, stearic, myristic, oil, nylon, caprylic, arachidic, etc.

V high molecular weight limiting fatty acids (stearic, arachidic, palmitic) have a solid consistency, low molecular weight(oil, nylon, etc.) - liquid. (most vegetable oils).

Solid fats are dominated by saturated fatty acids (animal and poultry fats). The more saturated fatty acids, the higher the melting point of the fat, the longer it is digested and less absorbed (mutton and beef fats).

The biological activity of saturated fatty acids is low.

Saturated fatty acids are associated with the idea of ​​their negative effect on fat metabolism and the development of atherosclerosis. There is evidence that an increase in blood cholesterol is associated with the intake of animal fats containing saturated fatty acids. Excessive intake of solid fats also contributes to the development of coronary heart disease, obesity, gallstone disease, etc.

Monounsaturated (monoenic) - refers to them oleic acid found in almost all animal and vegetable fats.

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 the function of the biliary tract.

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

Polyunsaturated (polyene, PUFA) - having two or more free double bonds.

These include linoleic acid having two double bonds, linolenic having three double bonds, and arachidonic having four double bonds. These acids, due to their biological properties, are called vitamin F... Linoleic and linolenic acids are indispensable (essential) nutrients, because

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. Arachidonic acid constitutes about 25% of the fatty acid composition of the membranes. From PUFAs, tissue hormone-like substances (prostaglandins) are formed in the body, they have a positive effect on fat metabolism in the liver, increase the elasticity of blood vessels, normalize the skin condition, and are necessary for the normal functioning of the brain.

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

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

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

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

Soft margarines, mayonnaise, and nuts are good sources of linoleic acid. Of cereals, it is most of all in millet, but 25 times less than in sunflower oil.

table 2

The amount of fatty acids (in g) per 100 g of fatty products.

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

Sources of linolenic acid are flaxseed oil, hemp oil, soybean oil, mustard oil, and rapeseed oil. 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 some products simultaneously contain 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 blood clots, stimulate immunity (participate in the formation of T-lymphocytes), prostaglandin production, have antioxidant and anticarcinogenic effects.

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

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

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

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.

Edible fats, when stored for a long time in the presence of oxygen and light, go rancid, which is associated with autooxidation unsaturated fatty acids. Long-term heat treatment has a negative effect on fats. In oxidized and overheated fats, vitamins are destroyed, the content of PUFA decreases, and harmful substances (peroxides, aldehydes, etc.) accumulate, causing irritation of the gastrointestinal tract and disrupting metabolism.

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

The human body has antioxidant protection, in case of insufficiency 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 the autooxidation of fatty acids and the rancidity of edible fats, antioxidants are introduced into fat-containing foods.

Trans fatty acid isomers (FFA)

Trans fatty acid isomers - special forms of unsaturated fatty acid molecules, sometimes called "freak molecules". TIZHK 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, TIZHK make up about 3% of all fats.

There is a lot of HFA (up to 14%) in the hydrogenated fats produced by the fat industry and 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 interlayers, etc.

They are used for frying various culinary products (pies, chicken, etc.).

There is evidence that HIGA, 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 PUFAs, and impairs the quality of breast milk fat in nursing mothers. It should be noted that we are not talking about the danger of consuming waffles with fat-containing layers or potato chips, but about the fact that these and similar products should not be abused in the daily diet of a healthy person.

Fat-like substances

Of significant value to the body are fat-like 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 walls, are essential for their permeability, metabolism between cells and the intracellular space.

Phospholipids in foods differ in chemical composition and biological action. The latter largely depends on the nature of the constituent amino alcohol.

In food, the most widely represented 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, because prevents the accumulation of excessive amounts of cholesterol in the body, promotes its breakdown and elimination. A sufficient amount of lecithin is of great importance in diets for atherosclerosis, liver disease, gallstone disease, in the diets of mental workers and the elderly, as well as in the diets of therapeutic and therapeutic-prophylactic 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% of lecithin, in most fish, cheese, butter, oatmeal - 0.4-0.5 g%, in fat cottage cheese, sour cream - 0, 2 g%. Buttermilk is a good source of lecithin with low fat content.

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

The most famous phytosterol ß-sitosterol, most of all 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 a part of cell membranes and, together with phospholipids and proteins, ensures selective membrane permeability and affects the activity of enzymes associated with them. Cholesterol is the source of the formation of bile acids, steroid hormones of the gonads and adrenal cortex (testosterone, cortisone, estradiol, etc.), vitamin D.

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

It is known that cholesterol is part of complex plasma proteins lipoproteins. High density lipoproteins (HDL), low density lipoproteins (LDL) and very low density lipoproteins (VLDL) are isolated. 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 disrupted, the vascular wall becomes fragile and fragile.

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

Part of cholesterol (about 30%) a person gets 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, the biosynthesis of cholesterol in the liver increases, and in the case of the predominance of PUFA, it decreases. Cholesterol metabolism is normalized by lecithin, methionine, vitamins C, B6, B12, etc., as well as trace elements.

In many foods, these substances are well balanced with cholesterol: cottage cheese, eggs, sea fish, some seafood. Therefore, individual foods and the entire diet must be assessed not only by the content of cholesterol, but also by the totality of many indicators. Currently, saturated fatty acids of animals and hydrogenated fats are attributed to more significant risk factors for the development of cardiovascular disease than dietary cholesterol.

Cholesterol is widely present in all foods of animal origin (tab.

The usual daily diet should contain no more than 300 mg of cholesterol. Heat treatment destroys about 20% of cholesterol.

Table 3.

Food sources of fat

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

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

Vegetable fats contain a lot of PUFA, vitamin E and ß-sitosterol, which helps to normalize 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 are vegetable oils (99.9% fat), nuts (53-65%), oatmeal (6.1%), buckwheat, millet (3.3%), etc.

A healthy diet should include a combination of animal and vegetable fats.

Low Calorie Fat Substitutes

The widespread prevalence of overweight and obesity among the population of economically developed countries caused the need to search and develop low-calorie fat substitutes, and also attracted attention to low-fat "light" foods.

There are two groups of fat substitutes.

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

The swollen particles give a fat sensation when chewing, and the calorie content of these substitutes is reduced to 1-2 kcal / g. Of the 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 regular proteins and carbohydrates.

Second group substitutes are synthetic substances that have the physical and technological properties of fats in food.

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

They replace fat in food in an equivalent weight ratio. Of the synthetic fat substitutes, the best known are fatty acid esters with sugars, such as sucrose polyester. It should be emphasized that there is a study of their safety and effectiveness.

The need for and rationing of fats in nutrition

Fat regulation 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 requires an average of 1.1 g of fat per 1 kg of body weight. Of the total amount of consumed fats, 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: 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 the increase in heat production, is increased by 5-7%, in the conditions of the south it is reduced by 5% of the total energy content of the diet. In high-altitude areas, fat consumption is limited, because in connection with a decrease in the oxygen content in the air at a reduced barometric pressure, the oxidation of fats in the body worsens and under-oxidized products of fat metabolism accumulate.

Fats or lipids are essential nutrients and are essential nutrients. Fats are classified into neutral (triglycerides) and fat-like substances (lipoids). Neutral fats are composed of glycine and fatty acids.

Lipoids: these include biologically active substances - phospholipids (they have high biological activity, are not a significant source of energy and do not belong to irreplaceable food components; lecithin, cephalin) and sterols (water-insoluble hydroaromatic alcohols of a complex structure and are subdivided 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) are formed;

Are a part of cells and tissues

Are solvents of vitamins A, D, E, K

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

They create protective and heat-insulating integuments - the subcutaneous fat layer protects a person from hypothermia;

Improves the taste of food;

They cause a feeling of long-term satiety.

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

Fat metabolism: Fats and lipoids (phosphotides, sterols, cerebrizides) 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 cell structures. The overwhelming majority of fat in the body is located in adipose tissue, the importance of fat in energy metabolism is great.

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 fat depends on: the nature of the diet, the amount of food, on the constitutional characteristics of a person, on the amount of energy consumption during muscular activity, on gender, on age.

The amount of protoplasmic fat (involved in the exchange of in-in) is stable and constant.

Formation and breakdown of fats in the body: F, absorbed in the intestine, enters the lymph and, in small quantities, into the circulatory system.

With abundant and prolonged nutrition, any one type of fat can change the composition of the fat deposited in the body.

With an abundant carbohydrate diet and the absence of F in the diet, the body can synthesize F from U. Some unsaturated fatty acids (linoleic, linolenic, arachidonic) are irreplaceable. The process of regulation of the metabolism of fat, also by the nervous and endocrine systems as well as by tissue mechanisms and 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 of fat and carbohydrate metabolism provides the body's energy requirements.

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