Fats are a complex complex of organic compounds, the main structural elements of which are glycerol and fatty acid.

The proportion of glycerol in the composition of fats is negligible.

Its quantity does not exceed 10%.

Fatty acids are essential for determining the properties of fats.

Fats contain a number of substances, of which phosphatides, sterols and fat-soluble vitamins are of the greatest physiological importance.

Fatty acid

In natural fats, fatty acids are found in a wide variety, there are about 60 of them.

All fatty acids in dietary fats contain even number carbon atoms.

Fatty acids are divided into saturated (saturated) and unsaturated (unsaturated).

Limit (saturated) fatty acids

Limit fatty acids in in large numbers found in animal fats.

Limit fatty acids that are part of animal fats

Of the saturated fatty acids, the most common

• palmitic
• stearic
• myristic
• oily
• kapron
• caprylic
• capric
• arachidic

High molecular weight saturated acids (stearic, arachidic, palmitic) have a solid consistency, low molecular weight (butyric, caproic, etc.) - liquid. The melting point also depends on the molecular weight. The higher the molecular weight of saturated fatty acids, the higher their melting point.

Various fats contain various quantities fatty acids. Yes, in coconut oil 9 fatty acids, in linseed - 6. This causes the formation of eutectic mixtures, i.e., alloys with a melting point, as a rule, lower than the melting point of the constituent components. The presence of triglyceride mixtures in dietary fats is of great physiological importance: they reduce the melting point of fat and thereby contribute to its emulsification in duodenum and better absorption.

Saturated (limiting) fatty acids are found in large quantities (more than 50%) in animal fats (lamb, beef, etc.) and in some vegetable oils (coconut, palm kernel).

By biological properties saturated fatty acids are inferior to unsaturated ones. Limiting (saturated) fatty acids are more likely to be associated with ideas about their negative effect on fat metabolism, on the function and condition of the liver, as well as with their contributing role in the development of atherosclerosis.

There is evidence that an increase in blood cholesterol is more associated with a high-calorie diet and the simultaneous intake of animal fats rich in saturated fatty acids.

Fatty acids are aliphatic carboxylic acids derived primarily from fats and oils. Natural fats usually contain even-numbered fatty acids because they are synthesized from two-carbon units that form a straight chain of carbon atoms. The chain may be saturated (not containing

double bonds) and unsaturated (containing one or more double bonds).

Nomenclature

The systematic name of a fatty acid is most often formed by adding the ending -ova (Geneva nomenclature) to the name of the hydrocarbon. At the same time, saturated acids have the ending -anoic (for example, octanoic), and unsaturated acids -enoic (for example, octadecenoic - oleic acid). Carbon atoms are numbered starting from the carboxyl group (containing carbon 1). The carbon atom following the carboxyl group is also called a-carbon. Carbon atom 3 is -carbon, and the carbon of the terminal methyl group (carbon) is co-carbon. Various conventions have been adopted to indicate the number of double bonds and their position, for example, D 9 means that the double bond in the fatty acid molecule is between carbon atoms 9 and 10; co 9 - a double bond between the ninth and tenth carbon atoms, if counted from the (o-end. Widely used names indicating the number of carbon atoms, the number of double bonds and their position are shown in Fig. 15.1. In fatty acids of animal organisms in the process of metabolism additional double bonds may be introduced, but always between the double bond already present (e.g. co 9, co 6 or co 3) and the carboxyl carbon; this results in the division of fatty acids into 3 families of animal origin or

Table 15.1. Saturated fatty acids

Rice. 15.1. Oleic acid (n-9; read: "n minus 9").

Saturated fatty acids

Saturated fatty acids are members of the homologous series starting with acetic acid. Examples are given in table. 15.1.

There are other members of the series, with a large number carbon atoms, they are found primarily in waxes. Several branched-chain fatty acids have been isolated - from both plant and animal organisms.

Unsaturated fatty acids (Table 15.2)

They are classified according to the degree of unsaturation.

A. Monounsaturated (monoethenoid, monoenoic) acids.

B. Polyneosaturated (polyegenoid, polyenoic) acids.

B. Eicosanoids. These compounds, formed from eicose-(20-C)-polyenoic fatty acids,

Table 15.2. Unsaturated fatty acids of physiological and nutritional importance

(see scan)

subdivided into prostanoids and lenkotrennes (LT). Prostanoids include the prostaglandins prostacyclins and thromboxanes (TOs). Sometimes the term prostaglandins is used in a less strict sense and means all prostanoids.

Prostaglaidins were originally found in seminal fluid but have since been found in virtually all mammalian tissues; they have a number of important physiological and pharmacological properties. They are synthesized in vivo by cyclization of a site in the center of the carbon chain of 20-C (eicosanoic) polyunsaturated fatty acids (for example, arachidonic acid) to form a cyclopentane ring (Fig. 15.2). A related series of compounds, thromboxanes, found in platelets, contain a cyclopentane ring that includes an oxygen atom (oxane ring) (Figure 15.3). Three different eicosanoic fatty acids lead to the formation of three groups of eicosanoids, differing in the number of double bonds in the side chains and PGL. The ring can be attached various groups giving

Rice. 15.2. Prostaglandin.

Rice. 15.3. Thromboxane

the beginning of several different types prostaglandins and thromboxanes, which are designated A, B, etc. For example, E-type prostaglandin contains a keto group in position 9, while -type prostaglandin has a hydroxyl group in the same position. Leukotrienes are the third group of eicosanoid derivatives, they are formed not by cyclization of fatty acids, but as a result of the action of enzymes of the lipoxygenase pathway (Fig. 15.4). They were first found in leukocytes and are characterized by the presence of three conjugated double bonds.

Rice. 15.4. Leukotriene

D. Other unsaturated fatty acids. In materials biological origin many other fatty acids have also been found containing, in particular, hydroxyl groups (ricinoleic acid) or cyclic groups.

Cis-trans isomerism of unsaturated fatty acids

The carbon chains of saturated fatty acids have a zigzag shape when they are stretched (as is the case with low temperatures). At higher temperatures, there is a rotation around a number of bonds, leading to a shortening of the chains - this is why biomembranes become thinner as the temperature rises. Unsaturated fatty acids exhibit geometric isomerism due to the difference in the orientation of atoms or groups relative to the double bond. If the acyl chains are located on one side of the double bond, an α-configuration is formed, which is characteristic, for example, for oleic acid; if they are located different sides, then the molecule is in the trans configuration, as in the case of elaidic acid, an isomer of oleic acid (Fig. 15.5). Naturally occurring polyunsaturated long chain fatty acids are nearly all in the cis configuration; in the area where the double bond is located, the molecule is "bent" and forms an angle of 120°.

Rice. 15.5. Geometric isomerism of fatty acids (oleic and elaidic acids).

Thus, oleic acid is L-shaped, while elaidic acid retains the "linear" trans configuration at the site containing the double bond. An increase in the number of cis-double bonds in fatty acids leads to an increase in the number of possible spatial configurations of the molecule. This can have a major impact on the packaging of molecules in membranes, as well as on the position of fatty acid molecules within more complex molecules such as phospholipids. The presence of double bonds in the -configuration changes these spatial relationships. Fatty acids in the trans configuration are present in some food products. Most of them are formed by-products in the process of hydrogenation, due to which fatty acids are converted into a saturated form; in this way, in particular, they achieve the "hardening" of natural oils in the production of margarine. In addition, some small amount of trans acids comes from animal fat - it contains trans acids formed by the action of microorganisms present in the rumen of ruminants.

Alcohols

The alcohols that make up lipids include glycerol, cholesterol and higher alcohols.

for example, cetyl alcohol, which is commonly found in waxes, as well as the polyisoprenoid alcohol dolichol (Fig. 15.27).

Fatty acid aldehydes

Fatty acids can be reduced to aldehydes. These compounds are found in natural fats both in the free and bound state.

Physiologically important properties of fatty acids

The physical properties of body lipids are mainly dependent on the length of the carbon chains and the degree of unsaturation of the corresponding fatty acids. Thus, the melting point of fatty acids with an even number of carbon atoms increases with increasing chain length and decreases with increasing degree of unsaturation. Triacylglycerol, in which all three chains are saturated fatty acids containing at least 12 carbon atoms each, is a solid at body temperature; if all three fatty acid residues are of the 18:2 type, then the corresponding triacylglycerol remains liquid at temperatures below 0 C. In practice, natural acylglycerols contain a mixture of fatty acids that provides a certain functional role. Membrane lipids, which should be in a liquid state, are more unsaturated than storage lipids. In tissues subjected to cooling - during hibernation or in extreme conditions - lipids are more unsaturated.

IN modern world life moves at a fast pace. Often there is not enough time even for sleep. fast food, saturated with fats, which is commonly called fast food, has almost completely won a place in the kitchen.

But thanks to the abundance of information about a healthy lifestyle, an increasing number of people are drawn to healthy lifestyle life. At the same time, many consider saturated fat the main source of all problems.

Let's figure out how justified the widespread opinion about the dangers of saturated fats is. In other words, should you eat foods rich in saturated fat at all?

Products with the maximum content of EFA:

The approximate amount is indicated in 100 g of the product

General characteristics of saturated fatty acids

From a chemical point of view, saturated fatty acids (SFA) are substances with single bonds of carbon atoms. These are the most concentrated fats.

EFAs can be natural or artificial origin. Artificial fats include margarine, natural - butter, lard, etc.

EFAs are found in meat, dairy and some herbal products nutrition.

Special property such fats is that they do not lose their solid form at room temperature. Saturated fats fill the human body with energy and are actively involved in the process of building cells.

Saturated fatty acids are butyric, caprylic, caproic, and acetic acid. As well as stearic, palmitic, capric acid and some others.

EFAs tend to be deposited in the body "in reserve" in the form of body fat. Under the action of hormones (epinephrine and norepinephrine, glucagon, etc.), EFAs are released into the bloodstream, releasing energy for the body.

Useful advice:

To identify products with more high content saturated fat is enough to compare their melting points. The leader will have a higher EFA content.

Daily requirement for saturated fatty acids

The need for saturated fatty acids is 5% of the total daily ration human nutrition. It is recommended to consume 1-1.3 g of fat per 1 kg of body weight. The need for saturated fatty acids is 25% of total fats. It is enough to eat 250 g of low-fat cottage cheese (0.5% fat content), 2 eggs, 2 tsp. olive oil.

The need for saturated fatty acids increases:

• at various lung diseases: tuberculosis, severe and launched forms pneumonia, bronchitis, early stages lung cancer;
• during the treatment of stomach ulcers, duodenal ulcers, gastritis. With stones in the liver, gallbladder or bladder;
• with general depletion of the human body;
• when the cold season comes and additional energy is spent on heating the body;
• during pregnancy and lactation;
• the inhabitants of the Far North.

The need for saturated fat is reduced:

• with a significant excess of body weight (you need to reduce the use of EFAs, but not completely eliminate them!);
• at high level blood cholesterol;
• cardiovascular diseases;
• with a decrease in the energy consumption of the body (rest, sedentary work hot season).

Digestibility of SFA

Saturated fatty acids are poorly absorbed by the body. The use of such fats involves a long-term processing of them into energy. It is best to use those products that have a small amount of fat.

Choose to eat lean chicken, turkey, fish is also suitable. Dairy products are better absorbed if they have a low percentage of fat.

Useful properties of saturated fatty acids, their effect on the body

Saturated fatty acids are considered to be the most harmful. But considering that breast milk, saturated with these acids in large quantities (in particular, lauric acid), which means that the use of fatty acids is inherent in nature. And it has great value for human life. You just need to know what foods to eat.

And you can get a lot of such benefits from fats! Animal fats are richest source energy for man. In addition, it is an indispensable component in the structure. cell membranes, as well as a member important process hormone synthesis. Only due to the presence of saturated fatty acids is successful absorption vitamins A, D, E, K and many trace elements.

Correct use saturated fatty acids improves potency, regulates and normalizes menstrual cycle. Optimal use fatty foods prolongs and improves the functioning of internal organs.

Interaction with other elements

For saturated fatty acids, it is very important to have an interaction with essential elements. These are vitamins that belong to the class of fat-soluble.

The first and most important on this list is vitamin A. It is found in carrots, persimmons, bell pepper, liver, sea buckthorn, egg yolks. Thanks to him - healthy skin, luxurious hair, strong nails.

An important element is also vitamin D, which ensures the prevention of rickets.

Signs of a lack of EFAs in the body

• disruption of work nervous system;
• underweight body;
• deterioration in the condition of nails, hair, skin;
• hormonal imbalance;
• infertility.

Signs of excess saturated fatty acids in the body:

• a significant excess of body weight;
• development of diabetes;
• increased blood pressure, disruption of the heart;
• the formation of stones in the kidneys and gallbladder.

Factors affecting the content of SFA in the body

Refusal to use EFA leads to increased load on the body, because it has to look for substitutes from other food sources in order to synthesize fats. Therefore, the use of SFA is an important factor the presence of saturated fat in the body.

Selection, storage and preparation of foods containing saturated fatty acids

Compliance with several simple rules during the selection, storage and preparation of foods will help keep saturated fatty acids healthy.

1. 1 Unless you have an increased energy expenditure, when choosing foods, it is better to give preference to those in which the capacity of saturated fats is low. This will allow the body to better absorb them. If you have foods high in saturated fatty acids, then you should just limit them to a small amount.
2. 2 The storage of fats will be long if moisture, high temperature, and light do not get into them. Otherwise, saturated fatty acids change their structure, which leads to a deterioration in the quality of the product.
3. 3 How to cook products with EFA? Cooking foods rich in saturated fats includes grilling, grilling, sautéing and

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. Animal base and vegetable fats- fatty acid, 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 that high temperature melting. They can be absorbed by the body without the participation bile acids, this determines their high nutritional value. However, excess saturated fatty acids are inevitably stored in reserve.

Main types saturated acids- palmitic, stearic, myristic. They are found in different amounts in fat, 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 disease, 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 foods plant origin and also 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 fat, avocado, peanuts, olives, cashew nuts, olive, sesame and rapeseed oils. Physiological need in MUFA is 10% of daily calories.

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. daily requirement in Omega-6 PUFA makes up 5-9% of daily calories.

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.

Poly unsaturated fats contains 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.

The one that raises blood levels bad cholesterol. This increases the risk of blockage of blood vessels and heart attacks, contributes to the development of diabetes.

conclusions

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.

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 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 one belongs 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 the aspect of them 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 first have a solid consistency, the second - liquid, the higher molar mass, the higher 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

by 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.

The list of foods high in saturated fats includes all meat products: pork, beef, lamb and different types birds. 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 the liquid vegetable oil under pressure and at temperatures up to 200 degrees active influence gaseous hydrogen. As a result, a new product is obtained - hydrogenated, having a distorted type of molecular structure. IN 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 the raw material used by the body to form cell membranes, as well as a source of biological substances actively participating in the processes of tissue regulation. This is especially true due to the increased last years formation risk malignant formations. 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 overuse increases the risk of a number of dangerous diseases.

What can be said in defense of fatty acids

For a long time, saturated foods have been "accused of involvement" in the increase in the level of bad cholesterol in the 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 mother's breast milk is rich in them and is good nutrition for a newborn. Therefore, for children and people with poor health, the use of such products can be beneficial.

In what ways can they harm?

If daily intake carbohydrates is more than 4 grams per kilogram of body weight, then you can observe how saturated fatty acids negatively 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.