The properties and functions of lipids depend on fatty acids. All about unsaturated fatty acids

The atoms in the molecules of the compounds are open, linear. The basis - . The number of its atoms in fat is always even.

Considering carbon in carboxyls, its particles can be from 4 to 24 ex. However, fat is not 20, but more than 200. Such a variety is associated with additional compound molecules, this is, as well as, a difference in structure. There are identical in composition and number of atoms, but differing in their arrangement. Such compounds are called isomers.

Like all fats free fatty acid lighter than water and do not dissolve in it. On the other hand, class substances dissociate in chloroform, diethyl ether, and acetone. All of these are organic solvents. Water is inorganic.

Fat people are not susceptible to these. Therefore, during the cooking of soup, fats collect on its surface and freeze into a crust on the surface of the dish, being in the refrigerator.

By the way, fats do not have a boiling point. The soup boils only water. in fats remain in the usual state. Changes its heating to 250 degrees.

But, even with it, the compounds do not boil, but are destroyed. The breakdown of glycerol gives the aldehyde acrolein. It is known, just like propenal. Substance Strong smell Besides, acrolein irritates mucous membranes.

Each fat individually has a boiling point. An oleic compound, for example, boils at 223 degrees. At the same time, the melting point of the substance is 209 marks on the Celsius scale lower. This indicates no saturation. This means that it contains double bonds. They make the molecule mobile.

Saturated fatty acids have only single bonds. They strengthen the molecules so the compounds stay at and below room temperature. However, we will talk about the types of fat in a separate chapter.

Types of fatty acids

The presence of only single bonds in saturated fatty molecules is caused by the completeness of each bond with hydrogen atoms. They make the structure of molecules dense.

The strength of the chemical bonds of saturated compounds allows them to remain intact even when boiled. Accordingly, in cooking, class substances retain their benefits, even in stews, even in soup.

unsaturated fatty acids with double bonds are divided according to their number. At least one bond between carbon atoms. Its two particles are bound to each other twice. Accordingly, the molecule lacks two hydrogen atoms. Such compounds are referred to as monounsaturated fatty acids.

If there are two or more double bonds in a molecule, this is an indication of polyunsaturated fatty acids. They lack at least four hydrogen atoms. Mobile carbon bonds make class substances unstable.

Passes easily fatty acid oxidation. Compounds deteriorate both in the light and during heat treatment. By the way, outwardly all polyunsaturated fatty acids are oily liquids. Their density is usually slightly less than that of water. The latter is close to one gram per cubic centimeter.

At the points of double bonds, the polyline saturated acids there are curls. Such springs in molecules do not allow atoms to stray into “crowds”. Therefore, the substances of the group remain liquid even in cold weather.

Monounsaturated at sub-zero temperatures harden. Tried to put olive oil in the refrigerator? The liquid solidifies because it contains oleic acid.

Unsaturated compounds are called omega fatty acids. The letter of the Latin alphabet in the name indicates the location of the double bond in the molecule. Hence the omega 3 fatty acids, omega-6 and omega-9. It turns out that in the first double bonds "start" from the 3rd carbon atom, in the second from the 6th, and in the 3rd from the 9th.

Scientists classify fat not only by the presence or absence of double bonds, but also by the length of atomic chains. In short-chain compounds from 4 to 6 carbon particles.

Such a structure is characteristic of exceptionally saturated fatty acids. Synthesis of them in the body is possible, but the lion's share comes with food, in particular, with dairy products.

Due to short chain compounds, they have antimicrobial action protecting the intestines and esophagus from pathogenic microorganisms. So, milk is not only good for bones and teeth.

Medium chain fatty acids have 8 to 12 carbon atoms. Their couplings are also found in dairy products. However, in addition to them, medium chain acids are also found in tropical fruit oils, for example, avocados. Remember how fat this fruit is? Oils in avocados occupy at least 20% of the weight of the fruit.

Like short-chain medium-length acid molecules, they have a disinfecting effect. Therefore, avocado pulp is added to oily masks. Fruit juices solve the problem of acne and other rashes.

The third group of fatty acids in terms of molecular length is long-chain fatty acids. They have 14 to 18 carbon atoms. With this composition, you can be saturated, and monounsaturated, and polyunsaturated.

Not every human body is able to synthesize such chains. Approximately 60% of the world's population "manufacture" long-chain acids from others. The ancestors of the rest of the people ate mainly meat and.

The animal diet reduced the production of a number of enzymes needed for self-production of long-chain fatty compounds. Meanwhile, they include those necessary for life, for example, arachidonic. It is involved in the construction of cell membranes, helps to transmit nerve impulses, and stimulates mental activity.

Fatty acids that are not produced by the human body are called essential. These include, for example, all compounds of the omega-3 group and most substances of the omega-6 category.

Omega-9 does not need to be produced. Group compounds are classified as non-essential. The body does not need such acids, but can use them as a substitute for more harmful compounds.

So, higher fatty acids omega-9s are becoming an alternative to saturated fats. The latter lead to an increase in the level of bad cholesterol. With omega-9 in the diet, cholesterol is kept normal.

Application of fatty acids

Omega fatty acids capsules are sold for food additives, cosmetics. Accordingly, substances are needed by the body, as internal organs as well as hair, skin, nails. The question of the role of fat in the body was touched upon in passing. Let's open the topic.

So, fatty unsaturated groups serve as oncoprotectors. This is the name given to compounds that inhibit the growth of tumors and, in general, their formation. It has been proven that a constant rate of omega-3 in the body minimizes the likelihood of prostate cancer in men and breast cancer in women.

In addition, fatty double bonds regulate the menstrual cycle. Its chronic failures are a reason to check the level of omega-3.6 in the blood, to include them in the diet.

The lipid barrier of the skin is a group of fatty acids. Here and unsaturated linolenic, and oleic and arachidonic. The film of them blocks the evaporation of moisture. As a result, the covers remain elastic, smooth.

Premature aging skin is often associated with a violation, thinning of the lipid barrier. Accordingly, dry skin is a signal of a lack of fatty acids in the body. acids. in feces you can check the level of required connections. It is enough to pass an extended analysis of the coprogram.

Without a lipid film, hair and nails dry, break, exfoliate. Not surprisingly, unsaturated fats are widely used by cosmetologists and pharmacists.

The emphasis on unsaturated acids is due to their benefits for the body and appearance. However, this does not mean that saturated compounds carry only. For the breakdown of substances with only single bonds, adrenal enzymes are not needed.

Saturated organism assimilates as simply and quickly as possible. This means that substances serve as an energy resource, like glucose. The main thing is not to overdo it with the consumption of saturated. The excess is immediately deposited in the subcutaneous adipose tissue. People consider saturated acids to be harmful because they often do not know the measure.

In industry, not so much come in handy free fatty acids how many of their connections. They mainly use their plastic properties. So, salts of fatty acids used to improve the lubricity of petroleum products. Enveloping parts with them is important, for example, in carburetor engines.

History of fatty acids

In the 21st century for fatty acids price usually bites. The hype about the benefits of omega-3s and omega-6s has caused consumers to shell out thousands for jars of nutritional supplements that contain only 20-30 tablets. Meanwhile, even 75 years ago there was no rumor about fat people. The heroines of the article owe their fame to Jim Dyerberg.

This is a chemist from Denmark. The professor became interested in why the Eskimos do not belong to the so-called cores. Dyerberg had a hypothesis that the reason was the diet of northerners. Fats predominated in their diet, which is not typical for the diet of southerners.

They began to study the composition of the blood of the Eskimos. We found an abundance of fatty acids in it, in particular, eicosapentaenoic and docosaxenoic. Jim Dyerberg introduced the names omega-3 and omega-6, however, did not prepare a sufficient evidence base for their effects on the body, including health.

This was already done in the 70s. By that time, they also studied the composition of the blood of the inhabitants of Japan and the Netherlands. Extensive research has made it possible to understand the mechanism of action of fats in the body and their importance. In particular, the heroines of the article are involved in the synthesis of prostaglandins.

These are enzymes. They are able to expand and narrow the bronchi, regulate muscle contractions and gastric secretion. Only now, it is difficult to figure out which ones are in excess in the body, and which ones are lacking.

Not yet invented fitness, "reading" all the indicators of the body, and even more cumbersome installation. It remains only to guess and be attentive to the manifestations of your body, nutrition.

Saturated(synonym marginal) fatty acid(English) saturated fatty acids) - monobasic fatty acids that do not have double or triple bonds between adjacent carbon atoms, that is, all such bonds are only single.

Do not include saturated fatty acids having one or more double bonds between carbon atoms. If there is only one double bond, such an acid is called monounsaturated. If there is more than one double bond, it is polyunsaturated.

Saturated fatty acids make up 33-38% of human subcutaneous fat (in descending order: palmitic, stearic, myristic and others).

Norms of consumption of saturated fatty acids

According to the Methodological recommendations MP 2.3.1.2432-08 "Norms of physiological needs for energy and nutrients ah for various groups population Russian Federation”, approved by Rospotrebnadzor on December 18, 2008: “The saturation of fat is determined by the number of hydrogen atoms that each fatty acid contains. fatty acids from medium length chains (C8-C14) are able to be absorbed in the digestive tract without the participation of bile acids and pancreatic lipase, are not deposited in the liver and undergo β-oxidation. Animal fats may contain saturated fatty acids with a chain length of up to twenty or more carbon atoms, they are solid and high temperature melting. Such animal fats include lamb, beef, pork and a number of others. A high intake of saturated fatty acids is the most important factor risk of developing diabetes, obesity, cardiovascular and other diseases.

Saturated fatty acid intake for adults and children should be no more than 10% from daily caloric intake.

The same norm: “saturated fatty acids should give no more than 10% of total number calories for all ages” is contained in the 2015-2020 Dietary Guidelines for Americans (the official publication of the US Department of Health).

Essential saturated fatty acids

Various authors determine in different ways which of the carboxylic acids are fatty. The broadest definition: fatty acids are carboxylic acids that do not have aromatic bonds. We will use the widely accepted approach, in which a fatty acid is a carboxylic acid that does not have branching and closed chains (but without specification regarding the minimum number of carbon atoms). With this approach general formula for saturated fatty acids is as follows: CH 3 -(CH 2) n -COOH (n=0.1.2...). Many sources do not classify the first two of this series of acids (acetic and propionic) as fatty acids. At the same time, in gastroenterology, acetic, propionic, butyric, valeric, caproic (and their isomers) belong to a subclass of fatty acids - short chain fatty acids(Minushkin O.N.). At the same time, an approach is widespread when acids from caproic to lauric are classified as medium-chain fatty acids, with a smaller number of carbon atoms - as short-chain, with a large number- to long chain.

Short-chain fatty acids containing no more than 8 carbon atoms (acetic, propionic, butyric, valeric, caproic and their isomers) can volatilize with water vapor when boiled, therefore they are called volatile fatty acids. Acetic, propionic and butyric acids are formed during anaerobic fermentation of carbohydrates, while protein metabolism leads to the formation of branched carbon carboxylic acids. The main carbohydrate substrate available to the intestinal microflora is the undigested remains of the shells. plant cells, slime. As a metabolic marker of anaerobic opportunistic microflora, volatile fatty acids in healthy people play the role of physiological regulators of motor function. digestive tract. However, when pathological processes affecting the intestinal microflora, their balance and dynamics of formation change markedly.

In nature predominantly fatty acids even number of carbon atoms. This is due to their synthesis, in which pairwise addition of carbon atoms occurs.

Name of the acid		Semi-expanded formula	Schematic representation
Trivial	Systematic	Semi-expanded formula	Schematic representation
Acetic	Ethane	CH 3 -COOH
propionic	propane	CH 3 -CH 2 -COOH
oily	Butane	CH 3 -(CH 2) 2 -COOH
Valerian	Pentane	CH 3 -(CH 2) 3 -COOH
Nylon	Hexane	CH 3 -(CH 2) 4 -COOH
Enanthic	Heptanoic	CH 3 -(CH 2) 5 -COOH
Caprylic	Octane	CH 3 -(CH 2) 6 -COOH
Pelargon	Nonanoic	CH 3 -(CH 2) 7 -COOH
capric	Dean's	CH 3 -(CH 2) 8 -COOH
Undecyl	Undecane	CH 3 -(CH 2) 9 -COOH
Lauric	Dodecanic	CH 3 -(CH 2) 10 -COOH
Tridecyl	Tridecanoic	CH 3 -(CH 2) 11 -COOH
Myristic	Tetradecanoic	CH 3 -(CH 2) 12 -COOH
Pentadecyl	Pentadecanoic	CH 3 -(CH 2) 13 -COOH
palmitic	Hexadecane	CH 3 -(CH 2) 14 -COOH
margarine	Heptadecanoic	CH 3 -(CH 2) 15 -COOH
Stearic	Octadecanic	CH 3 -(CH 2) 16 -COOH
Nonadecyl	Nonadecanic	CH 3 -(CH 2) 17 -COOH
Arachinoic	Eicosanoic	CH 3 -(CH 2) 18 -COOH
Heneicocylic	Geneicosanoic	CH 3 -(CH 2) 19 -COOH
Begenovaya	Docosane	CH 3 -(CH 2) 20 -COOH
Tricocylic	Tricosane	CH 3 -(CH 2) 21 -COOH
Lignoceric	Tetracosanoic	CH 3 -(CH 2) 22 -COOH
Pentacocylic	Pentacosane	CH 3 -(CH 2) 23 -COOH
Cerotin	Hexacosan	CH 3 -(CH 2) 24 -COOH
Heptacocylic	Heptacosanoic	CH 3 -(CH 2) 25 -COOH
Montanovaya	Octacosan	CH 3 -(CH 2) 26 -COOH
Nonacocylic	Nonacosan	CH 3 -(CH 2) 27 -COOH
Melissa	Triacontane	CH 3 -(CH 2) 28 -COOH
Gentriacontylic	Gentriacontanoic	CH 3 -(CH 2) 29 -COOH
Laceric	Dotriacontanoic	CH 3 -(CH 2) 30 -COOH

Saturated fatty acids in cow's milk

Saturated acids predominate in the composition of milk fat triglycerides, their general content ranges from 58 to 77% (the average is 65%), reaching a maximum in winter and a minimum in summer. Palmitic, myristic and stearic acids predominate among saturated acids. The content of stearic acid increases in summer, and that of myristic and palmitic acids in winter. This is due to the difference in feed rations and physiological characteristics (intensity of synthesis of individual fatty acids) of animals. Compared to animal fats and plant origin milk fat is characterized by a high content of myristic acid and low molecular weight volatile saturated fatty acids - butyric, caproic, caprylic and capric, in the amount of 7.4 to 9.5% total fatty acids. Percentage composition essential fatty acids (including their triglycerides) in milk fat (Bogatova O.V., Dogareva N.G.):

oil - 2.5-5.0%
nylon -1.0-3.5%
caprylic - 0.4-1.7%
capric - 0.8-3.6%
lauric -1.8-4.2%
myristic - 7.6-15.2%
palmitic - 20.0-36.0%
stearic -6.5-13.7%

Antibiotic activity of saturated fatty acids

All saturated fatty acids have antibiotic activity, but those with 8 to 16 carbon atoms are the most active. The most active of them is undecyl, which at a certain concentration inhibits growth Mycobacterium tuberculosis, Mycobacterium bovis, Escherichia coli, Salmonella paratyphi, Micrococcus luteus, Serratia marcescens, Shigella flexneri, Trichophyton gypseum. The antibiotic activity of saturated fatty acids significantly depends on the acidity of the medium. At pH = 6, caprylic and capric acids act on both gram-positive and gram-negative, and lauric and myristic acids - only on gram-positive bacteria. With an increase in pH, the activity of lauric acid in relation to Staphylococcus aureus and other gram-positive bacteria falls rapidly. With regard to gram-negative bacteria, the situation is opposite: at pH less than 7, lauric acid has almost no effect, but becomes very active at pH more than 9 (Shemyakin M.M.).

Among the saturated fatty acids even number carbon atoms, lauric acid has the highest antibiotic activity. It is also the most active against gram-positive microorganisms among all fatty acids with a short, up to 12 carbon atoms, chain. Fatty acids with a short, up to 6 carbon atoms, chain have a bactericidal effect on gram-negative microorganisms (Rybin V.G., Blinov Yu.G.).

Saturated fatty acids in medicines and dietary supplements

A number of saturated fatty acids, in particular, lauric and myristic acids, have bactericidal, viricidal and fungicidal activity, leading to the suppression of the development of pathogenic microflora and yeast fungi. These acids are able to potentiate in the intestine antibacterial action antibiotics, which can significantly increase the effectiveness of the treatment of acute intestinal infections of bacterial and viral-bacterial etiology. Some fatty acids, such as lauric and myristic, also act as an immunological stimulant when interacting with bacterial or viral antigens, helping to increase the body's immune response to the introduction of an intestinal pathogen (Novokshenov et al.). Presumably, caprylic acid inhibits the growth of yeast and maintains a normal balance of microorganisms in the colon, genitourinary system and on the skin, prevents overgrowth yeast fungi and, above all, the genus Candida without interfering with the growth of beneficial saprophytic bacteria. However, these qualities of saturated fatty acids are not used in medicines (these acids are practically absent among the active ingredients of medicines), in the composition of medicines they are used as Excipients, and manufacturers of dietary supplements and cosmetics focus on their aforementioned and other properties that may be beneficial to human health.

One of the few medicines, in which fatty acids are listed in the composition of the active substance, highly purified fish oil, this is Omegaven (ATC code "B05BA02 Fatty emulsions"). Among other fatty acids, saturated ones are mentioned:

palmitic acid - 2.5-10 g (per 100 g of fish oil)
myristic acid - 1-6 g (per 100 g of fish oil)
stearic acid - 0.5-2 g (per 100 g of fish oil)

Saturated fatty acids in cosmetics and detergents


Men Expert L "Oreal cleanser contains saturated fatty acids: myristic, stearic, palmitic and lauric	Dove cream soap contains saturated fatty acids: stearic and lauric

laundry soap

Saturated fatty acids in Food Industry

food additive

Saturated fatty acids have contraindications, side effects and application features; when used for health purposes or as part of drugs or dietary supplements, consultation with a specialist is necessary.

This topic has gained its popularity relatively recently - since the time when humanity began strenuously striving for harmony. It was then that they started talking about the benefits and harms of fats. Researchers classify them based on the chemical formula based on the presence of double bonds. The presence or absence of the latter makes it possible to divide fatty acids into two large groups: unsaturated and saturated.

A lot has been written about the properties of each of them, and it is believed that the first refers to healthy fats, but the second one is not. It is fundamentally wrong to confirm the truth of this conclusion unequivocally or to refute it. Anyone matters to full development person. In other words, let's try to figure out what the benefits are and whether there is harm from the use of saturated fatty acids.

Features of the chemical formula

If approached in terms of their molecular structure, then the right step will turn to science for help. First, remembering chemistry, we note that fatty acids are inherently hydrocarbon compounds, and their atomic structure is formed in the form of a chain. The second is that carbon atoms are tetravalent. And at the end of the chain, they are connected to three particles of hydrogen and one carbon. In the middle they are surrounded by two atoms of carbon and hydrogen. As you can see, the chain is completely filled - there is no way to attach at least one more hydrogen particle.

The saturated fatty acid formula is best represented. These are substances whose molecules are a carbon chain, in their chemical structure they are simpler than other fats and contain a pair of carbon atoms. They get their name on the basis of a system of saturated hydrocarbons with a certain chain length. Formula in general:

Some properties of these compounds are characterized by such an indicator as the melting point. They are also divided into types: high molecular weight and low molecular weight. The former have a solid consistency, the latter are liquid, the higher the molar mass, the greater the temperature at which they melt.

They are also called monobasic, due to the fact that in their structure there are no double bonds between adjacent carbon atoms. This leads to the fact that their reactivity decreases - it is more difficult for the human body to break them down, and this process, accordingly, takes more energy.

Characteristics

The most prominent representative and perhaps the most famous saturated fatty acid is palmitic, or as it is also called, hexadecanoic. Its molecule includes 16 carbon atoms (C16:0) and not a single double bond. About 30-35 percent of it is contained in human lipids. This is one of the main types of saturated acids found in bacteria. It is also present in the fats of various animals and a number of plants, for example, in the notorious palm oil.

Stearic and arachidic saturated fatty acids are characterized by a large number of carbon atoms, the formulas of which include 18 and 20, respectively. The first is found in large quantities in mutton fat - here it can be up to 30%, it is also present in vegetable oils - about 10%. Arachinic, or - in accordance with its systematic name - eicosanoic, is found in butter and peanut butter.

All these substances are macromolecular compounds and are solid in their consistency.

"Saturated" foods

Today it is difficult to imagine modern cuisine without them. Limit fatty acids are found in products of both animal and vegetable origin. However, comparing their content in both groups, it should be noted that in the first case their percentage is higher than in the second.

To the list of products containing in large quantities saturated fat, include all meat products: pork, beef, lamb and various types of poultry. The group of dairy products can also boast of their presence: ice cream, sour cream, and milk itself can also be attributed here. Also, limiting fats are found in some palm and coconut.

A bit about artificial products

The group of saturated fatty acids also includes such an “achievement” of the modern food industry as trans fats. They are obtained by The essence of the process is that liquid vegetable oil under pressure and at temperatures up to 200 degrees is subjected to active influence gaseous hydrogen. As a result, a new product is obtained - hydrogenated, having a distorted type molecular structure. AT natural environment there are no such connections. The purpose of such a transformation is not directed at all to the benefit human health, but is caused by the desire to obtain a "convenient" solid product that improves taste, with good texture and a long shelf life.

The role of saturated fatty acids in the functioning of the human body

The biological functions assigned to these compounds are to supply the body with energy. Their plant representatives are raw materials used by the body to form cell membranes, as well as a source of biological substances that are actively involved in the processes of tissue regulation. This is especially true due to the increased risk of developing malignant tumors in recent years. Saturated fatty acids are involved in the synthesis of hormones, the absorption of vitamins and various trace elements. Reducing their intake can negatively affect a man's health, as they are involved in the production of testosterone.

Benefits or harms of saturated fats

The question of their harm remains open, since no direct connection with the occurrence of diseases has been identified. However, there is an assumption that excessive consumption increases the risk of a number of dangerous diseases.

What can be said in defense of fatty acids

Long enough rich foods"accused of being involved" in the rise in the level bad cholesterol in blood. Modern dietetics justified them by establishing that the presence in meat palmitic acid and stearic in dairy products in itself in no way affects the indicator of "bad" cholesterol. Carbohydrates were recognized as the culprit for its increase. As long as their content is low, fatty acids do not pose any harm.

It has also been found that by reducing carbohydrate intake while increasing the amount of “saturated foods” consumed, there is even a slight increase in the level of “good” cholesterol, which indicates their benefits.

It should be noted here that at a certain stage of a person's life, this type of saturated fatty acids becomes simply necessary. It is known that maternal breast milk rich in them and is a complete nutrition for the newborn. Therefore, for children and people with poor health, the use of such products can be beneficial.

In what ways can they harm?

If the daily intake of carbohydrates is more than 4 grams per kilogram of body weight, then you can observe how negatively saturated fatty acids affect health. Examples confirming this fact: palmitic, which is found in meat, provokes a decrease in insulin activity, stearic, present in dairy products, actively contributes to the formation of subcutaneous fat deposits and negatively affects the cardiovascular system.

Here we can conclude that an increase in carbohydrate intake can turn "saturated" foods into the category of unhealthy.

Delicious Health Threat

Characterizing "naturally produced" saturated fatty acids, the harm of which has not been proven, one should also remember about artificial - hydrogenated, obtained by forced saturation of vegetable fats with hydrogen.

This should include margarine, which, largely due to its low cost, is actively used: in the production of various confectionery products, various semi-finished products and in places for cooking. The use of this product and its derivatives is not good for health. Moreover, it gives rise to serious illnesses like diabetes, cancer, ischemic disease heart, blockage of blood vessels.

Fats in the human body play both an energy and a plastic role. In addition, they are good solvents for a number of vitamins and sources of biologically active substances.

Fat boost taste qualities food and causes a feeling of long-term satiety.

The role of fats in the process is great cooking food. They give it special tenderness, improve organoleptic qualities and increase nutritional value. Due to the low oxidizability of fat, 1 g of it during combustion gives 9.0 kcal, or 37.7 kJ.

There are protoplasmic fat, which is a structural element of the protoplasm of cells, and spare, or reserve, which is deposited in adipose tissue. With a lack of fat in diet there are disturbances in the state of the body (weakening of immunological and protective mechanisms, changes in the skin, kidneys, organs of vision, etc.). Animal experiments have shown a shortening of life expectancy with insufficient fat content in the diet of animals.

CHEMICAL COMPOSITION AND BIOLOGICAL VALUE OF FAT

Fatty acids are divided into limiting (saturated) and unsaturated (unsaturated). The most common saturated fatty acids are palmitic, stearic, butyric and caproic. Palmitic and stearic acids are high molecular weight and are solids.

Saturated fatty acids are found in animal fats. They have low biological activity and can have a negative effect on fat and cholesterol metabolism.

Unsaturated fatty acids are widely present in all dietary fats, but most of them are found in vegetable oils. They contain double unsaturated bonds, which determines their significant biological activity and ability to oxidize. The most common are oleic, linoleic, linolenic and arachidonic fatty acids, among which arachidonic acid has the highest activity.

Unsaturated fatty acids are not formed in the body and must be administered daily with food in the amount of 8-10 g. Sources of oleic, linoleic and linolenic fatty acids are vegetable oils. Arachidonic fatty acid is almost not found in any product and can be synthesized in the body from linoleic acid in the presence of vitamin B 6 (pyridoxine).

The lack of unsaturated fatty acids leads to growth retardation, dryness and inflammation of the skin.

Unsaturated fatty acids are part of membrane system cells, myelin sheaths and connective tissue. Known for their participation in fat metabolism and in the conversion of cholesterol into easily soluble compounds that are excreted from the body.

To meet the physiological needs of the body in unsaturated fatty acids, it is necessary to introduce 15-20 g of vegetable oil into the diet daily.

Sunflower, soybean, corn, linseed and cottonseed oils have a high biological activity of fatty acids, in which the content of unsaturated fatty acids is 50-80%.

The biological value of fats is characterized by their good digestibility and the presence in their composition, in addition to unsaturated fatty acids, tocopherols, vitamins A and D, phosphatides and sterols. Unfortunately, none of the dietary fats meet these requirements.

FAT-LIKE SUBSTANCES.

Certain value for the body and fat-like substances - phospholipids and sterols. Of the phospholipids, the most active action contains lecithin, which promotes digestion and better exchange fats, increased bile secretion.

Lecithin has a lipotropic effect, i.e. it prevents fatty liver, prevents the deposition of cholesterol in the walls blood vessels. A lot of lecithin is found in egg yolks, in milk fat, in unrefined vegetable oils.

The most important representative of sterols is cholesterol, which is part of all cells; especially a lot of it in the nervous tissue.

Cholesterol is part of the blood, is involved in the formation of vitamin D3, bile acids, sex gland hormones.

Violation of cholesterol metabolism leads to atherosclerosis. From fats and carbohydrates in the human body per day, about 2 g of cholesterol is formed, 0.2-0.5 g comes with food.

The predominance of saturated fatty acids in the diet enhances the formation of endogenous (internal) cholesterol. The largest number cholesterol is found in brains, egg yolk, kidneys, fatty varieties meat and fish, caviar, butter, sour cream and cream.

Cholesterol metabolism in the body is normalized by various lipotropic substances.

In the body there is a close relationship between the exchange of lecithin and cholesterol. Under the influence of lecithin, the level of cholesterol in the blood decreases.

To normalize fat and cholesterol metabolism, a diet rich in lecithin is necessary. With the introduction of lecithin into the diet, it is possible to reduce the level of cholesterol in the blood serum, even if foods containing a large amount of fat are included in the diet.

Overheated fats.

The production of crispy potatoes, fish sticks, frying vegetables and canned fish, as well as the preparation of fried pies and donuts. Vegetable oils used for these purposes are subjected to heat treatment in the temperature range from 180 to 250 °C. With prolonged heating of vegetable oils, the process of oxidation and polymerization of unsaturated fatty acids occurs, resulting in the formation of cyclic monomers, dimers and higher polymers. At the same time, the unsaturation of the oil decreases and the products of oxidation and polymerization accumulate in it. Oxidation products formed as a result of prolonged heating of the oil reduce its nutritional value and cause the destruction of phosphatides and vitamins in it.

In addition, this oil has an adverse effect on the human body. It has been established that prolonged use of it can cause severe irritation gastrointestinal tract and cause the development of gastritis.

Overheated fats also affect fat metabolism.

Changes in organoleptic and physical and chemical properties vegetable oils used for frying vegetables, fish and pies, usually occurs in case of non-compliance with the technology of their preparation and violation of the instructions "On the procedure for frying pies, using deep fat and controlling its quality", when the duration of heating the oil exceeds 5 hours, and the temperature - 190 °C. The total amount of fat oxidation products should not exceed 1%.

The body's need for fat.

Normalization of fat is carried out depending on the age of the person, the nature of his labor activity and climatic conditions. In table. 5 shows the daily requirement for fats of the adult working population.

For young and middle-aged people, the ratio of protein to fat can be 1:1 or 1:1.1. The need for fat also depends on climatic conditions. In the northern climatic zones, the amount of fat can be 38-40% of the daily calorie content, in the middle - 33, in the southern - 27-30%.

Biologically optimal is the ratio in the diet of 70% animal fat and 30% vegetable fat. In adulthood and old age

Labor Intensity Groups	Gender and age, years

the ratio can be changed in the direction of increasing the specific gravity of vegetable fats. This ratio of fats allows you to provide the body with a balanced amount of fatty acids, vitamins and fat-like substances.

Fat is an active reserve of energy material. With fats, the substances necessary to maintain the activity of the body come: in particular, vitamins E, D, A. Fats help the absorption of a number of nutrients from the intestines. The nutritional value fats is determined by their fatty acid composition, melting point, the presence of essential fatty acids, the degree of freshness, and taste. Fats are made up of fatty acids and glycerol. The value of fats (lipids) is diverse. Fats are contained in cells and tissues, participating in metabolic processes.

AT liquid fats are unsaturated fatty acids(most vegetable oils and fish fats contain them), in solid fats - saturated fatty acids - fats of animals and birds. Of the solid fats, mutton and beef fat are the most refractory and difficult to digest, and milk fat is the easiest. The biological value is higher than v fats rich in unsaturated fatty acids.

Of particular importance are POLYUNSATURATED ESSENTIAL FATTY ACIDS: linoleic and arachidonic. Like vitamins, they are almost never produced by the body and must be obtained from food. These substances are an important component cell membranes necessary to regulate metabolism, especially cholesterol metabolism, form tissue hormones (prostaglandins). Sunflower, corn and cottonseed oil contains about 50% linoleic acid. 15-25 g of these oils fill the daily requirement for essential fatty acids. This amount is increased to 25-35 g in atherosclerosis, diabetes mellitus e, obesity and other diseases. However long-term use very large amounts of these fats can be unfavorable for the body. These acids are relatively rich in fish fats, poor (3-5%) mutton and beef fats, butter.

Lecithin belongs to fat-like substances - phosphatides - which promotes digestion and good exchange fat and protein form cell membranes. It also normalizes cholesterol metabolism.

Lecithin also has a lipotropic effect, since it reduces the concentration of fats in the liver, preventing its obesity in diseases and the action of various poisons. Fat-like substance cholesterol is involved in the formation of essential acids in the body. Deposition of cholesterol in the lining of the arteries main feature atherosclerosis.

Vegetable products do not contain cholesterol.

Cholesterol limit diet to 300-400 mg per day for atherosclerosis, cholelithiasis, diabetes, decreased function thyroid gland etc. However, it must be borne in mind that even in healthy body cholesterol is formed 3-4 times more than it comes with food. An increase in cholesterol levels is due to different reasons, including malnutrition, (excess of animal fats and sugar in food), violation of the diet.

Cholesterol metabolism is normalized by essential fatty acids, lecithin, methionine, a number of vitamins and microelements.

Fat must be fresh. Since fats are very easily oxidized. Overheated or stale fats accumulate harmful substances that lead to irritation. gastrointestinal tract, kidney, disrupting metabolism. Such fats are strictly prohibited in the diet. Need healthy person in various fats - 80-100 g per day. In the diet, the quantitative and qualitative composition of fats can change. Reduced quantity fats, especially refractory ones, are recommended to be used for atherosclerosis, pancreatitis, hepatitis, exacerbation of enterocolitis, diabetes, obesity. And when the body is depleted after serious illnesses and with tuberculosis, it is recommended, on the contrary, to increase the intake of fat to 100-120 g per day.

Fats are macronutrients, necessary participants in the nutrition of each person. The daily diet should include different fats, each of them performs its own function.

From a physiological point of view, fats are an integral part of the three macronutrients that provide the basic needs of the human body. They are one of the main sources of energy. Fats - constituent element of all cells, they are necessary for the assimilation fat soluble vitamins, provide thermal insulation of the body, participate in the activity of the nervous system and immunity.

The official name for fats in food is lipids. Those lipids that are part of the cells are called structural (phospholipids, lipoproteins), others are a way of storing energy and are called reserve (triglycerides).

The energy value fats are about twice the energy value of carbohydrates.

Chemically, fats are esters of glycerol and higher fatty acids. The basis of animal and vegetable fats is fatty acids, different composition which determines their functions in the body. All fatty acids are divided into two groups: saturated and unsaturated.

Saturated fatty acids

Saturated fatty acids are found mainly in animal fats. These are solids with a high melting point. They can be absorbed by the body without the participation of bile acids, this determines their high nutritional value. However, excess saturated fatty acids are inevitably stored in reserve.

The main types of saturated acids are palmitic, stearic, myristic. They are found in different amounts in lard, fatty meat, dairy products (butter, sour cream, milk, cheeses, etc.). Animal fats, which contain saturated fatty acids, have pleasant taste, contain lecithin and vitamins A and D, as well as cholesterol.

Cholesterol is the main sterol of animal origin, it is vital for the body, since it is part of all cells and tissues of the body, participates in hormonal processes and the synthesis of vitamin D. At the same time, an excess of cholesterol in food leads to an increase in its level in the blood, which is one of the main risk factors for development cardiovascular diseases, diabetes and obesity. Cholesterol is synthesized by the body from carbohydrates, so it is recommended to consume no more than 300 mg per day with food.

The preferred form of consumption of saturated fatty acids is dairy products, eggs, organ meats (liver, heart), fish. The proportion of saturated fatty acids in daily diet should account for no more than 10% of calories.

unsaturated fatty acids

Unsaturated fatty acids are found mainly in plant foods, as well as in fish. Unsaturated fatty acids are easily oxidized, they are not very resistant to heat treatment, so it is most useful to eat foods containing them raw.

Unsaturated fatty acids are divided into two groups, depending on how many unsaturated hydrogen bonds between atoms are in them. If there is one such bond, these are monounsaturated fatty acids (MUFAs), if there are several of them, these are polyunsaturated fatty acids (PUFAs).

Monounsaturated fatty acids

The main types of MUFAs are myristoleic, palmitoleic, and oleic. These acids can be synthesized by the body from saturated fatty acids and carbohydrates. One of essential functions MUFA - lowering blood cholesterol levels. The sterol contained in MUFAs, p-sitosterol, is responsible for this. It forms an insoluble complex with cholesterol and thus interferes with the absorption of the latter.

The main source of MUFAs is fish oil, avocado, peanuts, olives, cashews, olive, sesame and rapeseed oils. The physiological need for MUFA is 10% of the daily caloric intake.

Vegetable fats are mostly poly- or monounsaturated. These fats can lower blood cholesterol levels and often contain essential fatty acids (EFAs): omega-3 and omega-6.

Polyunsaturated fatty acids

The main types of polyunsaturated fatty acids are linoleic, linolenic, arachidonic. These acids are not only part of the cells, but also participate in metabolism, provide growth processes, contain tocopherols, p-sitosterol. PUFAs are not synthesized by the human body, therefore are considered essential along with some amino acids and vitamins. The greatest biological activity is arachidonic acid, which is scarce in food, but with the participation of vitamin B6, it can be synthesized by the body from linoleic acid.

Arachidonic and linoleic acid belong to the omega-6 family of acids. These acids are found in almost all vegetable oils and nuts. The daily requirement for Omega-6 PUFAs is 5-9% of the daily caloric intake.

Alpha-linolenic acid belongs to the Omega-3 family. The main source of this family of PUFAs is fish oil and some seafood. The daily requirement for Omega-3 PUFAs is 1-2% of the daily caloric intake.

An excess of PUFA-containing foods in the diet can cause kidney and liver disease.

Polyunsaturated fats are found in fish, walnuts, almonds, flax, some spices, soybean oil, sunflower oil, etc.

Trans fats

(or) obtained by processing vegetable fats, used in the manufacture of margarine and other cooking oils. Accordingly, it gets into chips, hamburgers and most of the store baked goods.

That raises the level of bad cholesterol in the blood. This increases the risk of blockage of blood vessels and heart attacks, contributes to the development of diabetes.

findings

The use of fats is necessary for the full functioning of the body. But everything must be done wisely.

The benefits of fat, even unsaturated fat, are possible only with its proper use. The energy value of fat is unusually high. A glass of seeds is equal in calories to one barbecue or a whole bar of chocolate. If you abuse unsaturated fats, they will bring less harm than saturated.

The positive value of fats for the body is undeniable, subject to simple rules: Minimize the intake of saturated fats, completely eliminate trans fats, consume unsaturated fats moderately and regularly.