LIPIDS - this is a heterogeneous group of natural compounds, completely or almost completely insoluble in water, but soluble in organic solvents and in each other, yielding high molecular weight fatty acids upon hydrolysis.
In a living organism, lipids perform various functions.
Biological functions of lipids:
1) Structural
Structural lipids form complex complexes with proteins and carbohydrates, from which the membranes of cells and cellular structures are built, and participate in a variety of processes occurring in the cell.
2) Spare (energy)
Reserve lipids (mainly fats) are the body's energy reserve and participate in metabolic processes. In plants they accumulate mainly in fruits and seeds, in animals and fish - in subcutaneous fatty tissues and tissues surrounding internal organs, as well as liver, brain and nervous tissues. Their content depends on many factors (type, age, nutrition, etc.) and in some cases accounts for 95-97% of all secreted lipids.
Calorie content of carbohydrates and proteins: ~ 4 kcal/gram.
Caloric content of fat: ~ 9 kcal/gram.
The advantage of fat as an energy reserve, unlike carbohydrates, is its hydrophobicity - it is not associated with water. This ensures compactness of fat reserves - they are stored in anhydrous form, occupying a small volume. The average person's supply of pure triacylglycerols is approximately 13 kg. These reserves could be enough for 40 days of fasting under conditions of moderate physical activity. For comparison: total reserves glycogen in the body - approximately 400 g; when fasting, this amount is not enough even for one day.
3) Protective
Subcutaneous adipose tissue protects animals from cooling, and internal organs from mechanical damage.
The formation of fat reserves in the body of humans and some animals is considered an adaptation to irregular nutrition and living in a cold environment. Animals that hibernate for a long time (bears, marmots) and are adapted to living in cold conditions (walruses, seals) have a particularly large reserve of fat. The fetus has virtually no fat and appears only before birth.
A special group in terms of their functions in a living organism are the protective lipids of plants - waxes and their derivatives, covering the surface of leaves, seeds and fruits.
4) An important component of food raw materials
Lipids are an important component food, largely determining its nutritional value and taste. The role of lipids in various food technology processes is extremely important. Spoilage of grain and its processed products during storage (rancidity) is primarily associated with changes in its lipid complex. Lipids isolated from a number of plants and animals are the main raw materials for obtaining the most important food and technical products (vegetable oil, animal fats, including butter, margarine, glycerin, fatty acids, etc.).
2 Classification of lipids
There is no generally accepted classification of lipids.
It is most appropriate to classify lipids depending on their chemical nature, biological functions, as well as in relation to some reagents, for example, alkalis.
Based on their chemical composition, lipids are usually divided into two groups: simple and complex.
Simple lipids – esters of fatty acids and alcohols. These include fats , waxes And steroids .
Fats – esters of glycerol and higher fatty acids.
Waxes – esters of higher alcohols of the aliphatic series (with a long carbohydrate chain of 16-30 C atoms) and higher fatty acids.
Steroids – esters of polycyclic alcohols and higher fatty acids.
Complex lipids – in addition to fatty acids and alcohols, they contain other components of various chemical natures. These include phospholipids and glycolipids .
Phospholipids - This complex lipids, in which one of alcohol groups is not associated with FA, but with phosphoric acid (phosphoric acid can be combined with an additional compound). Depending on which alcohol is included in the phospholipids, they are divided into glycerophospholipids (contain the alcohol glycerol) and sphingophospholipids (contain the alcohol sphingosine).
Glycolipids – these are complex lipids in which one of the alcohol groups is associated not with FA, but with a carbohydrate component. Depending on which carbohydrate component is part of the glycolipids, they are divided into cerebrosides (they contain a monosaccharide, disaccharide or a small neutral homooligosaccharide as a carbohydrate component) and gangliosides (they contain an acidic heterooligosaccharide as a carbohydrate component).
Sometimes into an independent group of lipids ( minor lipids ) secrete fat-soluble pigments, sterols, and fat-soluble vitamins. Some of these compounds can be classified as simple (neutral) lipids, others - complex.
According to another classification, lipids, depending on their relationship to alkalis, are divided into two large groups: saponifiable and unsaponifiable. The group of saponified lipids includes simple and complex lipids, which, when interacting with alkalis, hydrolyze to form salts of high molecular weight acids, called “soaps”. The group of unsaponifiable lipids includes compounds that are not subject to alkaline hydrolysis (sterols, fat-soluble vitamins, ethers, etc.).
According to their functions in a living organism, lipids are divided into structural, storage and protective.
Structural lipids are mainly phospholipids.
Storage lipids are mainly fats.
Protective lipids of plants - waxes and their derivatives, covering the surface of leaves, seeds and fruits, animals - fats.
FATS
The chemical name of fats is acylglycerols. These are esters of glycerol and higher fatty acids. "Acyl" means "fatty acid residue".
Depending on the number of acyl radicals, fats are divided into mono-, di- and triglycerides. If the molecule contains 1 fatty acid radical, then the fat is called MONOACYLGLYCEROL. If the molecule contains 2 fatty acid radicals, then the fat is called DIACYLGLYCEROL. In the human and animal body, TRIACYLGLYCEROLS predominate (contain three fatty acid radicals).
The three hydroxyls of glycerol can be esterified either with only one acid, such as palmitic or oleic, or with two or three different acids:
Natural fats contain mainly mixed triglycerides, including residues of various acids.
Since the alcohol in all natural fats is the same - glycerol, the differences observed between fats are due solely to the composition of fatty acids.
Over four hundred carboxylic acids of various structures have been found in fats. However, most of them are present only in small quantities.
The acids contained in natural fats are monocarboxylic acids, built from unbranched carbon chains containing an even number of carbon atoms. Acids containing an odd number of carbon atoms, having a branched carbon chain, or containing cyclic moieties are present in small quantities. The exceptions are isovaleric acid and a number of cyclic acids found in some very rare fats.
The most common acids in fats contain 12 to 18 carbon atoms and are often called fatty acids. Many fats contain small amounts of low molecular weight acids (C 2 -C 10). Acids with more than 24 carbon atoms are present in waxes.
The glycerides of the most common fats contain significant quantities of unsaturated acids containing 1-3 double bonds: oleic, linoleic and linolenic. Arachidonic acid containing four double bonds is present in animal fats; acids with five, six or more double bonds are found in fats of fish and marine animals. Most unsaturated acids of lipids have a cis configuration, their double bonds are isolated or separated by a methylene (-CH 2 -) group.
Of all the unsaturated acids contained in natural fats, oleic acid is the most common. In many fats, oleic acid makes up more than half of the total mass of acids, and only a few fats contain less than 10%. Two other unsaturated acids - linoleic and linolenic acid - are also very widespread, although they are present in much smaller quantities than oleic acid. Linoleic and linolenic acids are found in noticeable quantities in vegetable oils; For animal organisms they are essential acids.
Of the saturated acids, palmitic acid is almost as widespread as oleic acid. It is present in all fats, with some containing 15-50% of the total acid content. Stearic and myristic acids are widely used. Stearic acid is found in large quantities (25% or more) only in the storage fats of some mammals (for example, in sheep fat) and in the fats of some tropical plants, such as cocoa butter.
It is advisable to divide the acids contained in fats into two categories: major and minor acids. The main acids of fat are acids whose content in fat exceeds 10%.
Physical properties of fats
As a rule, fats do not withstand distillation and decompose even if they are distilled under reduced pressure.
The melting point, and therefore the consistency of fats, depends on the structure of the acids that make up them. Solid fats, i.e. fats that melt at a relatively high temperature, consist predominantly of glycerides of saturated acids (stearic, palmitic), and oils that melt at a lower temperature and are thick liquids contain significant amounts of glycerides of unsaturated acids (oleic , linoleic, linolenic).
Since natural fats are complex mixtures of mixed glycerides, they do not melt at a certain temperature, but in a certain temperature range, and they are first softened. To characterize fats, it is usually used solidification temperature, which does not coincide with the melting point - it is slightly lower. Some natural fats are solids; others are liquids (oils). The solidification temperature varies widely: -27 °C for linseed oil, -18 °C for sunflower oil, 19-24 °C for cow lard and 30-38 °C for beef lard.
The solidification temperature of fat is determined by the nature of its constituent acids: the higher the content of saturated acids, the higher it is.
Fats are soluble in ether, polyhalogen derivatives, carbon disulfide, aromatic hydrocarbons (benzene, toluene) and gasoline. Solid fats are poorly soluble in petroleum ether; insoluble in cold alcohol. Fats are insoluble in water, but they can form emulsions that are stabilized in the presence of surfactants (emulsifiers) such as proteins, soaps and some sulfonic acids, mainly in a slightly alkaline environment. Milk is a natural fat emulsion stabilized by proteins.
Chemical properties of fats
Fats undergo all chemical reactions characteristic of esters, but their chemical behavior has a number of features associated with the structure of fatty acids and glycerol.
Among the chemical reactions involving fats, several types of transformations are distinguished.
The main rule for maintaining health is to evenly distribute the proportion of fat when serving a dish. In fact, a person needs fats, but he must control the amount of fat consumed. A person must determine for himself the amount of fat that will be beneficial and not harmful to health. Fat must go into the right direction, to avoid unpleasant consequences associated with weight gain, which leads to heart problems, hypertension, stroke or even death. Therefore, it is worth paying attention to foods that help burn fat. Today we will look at 10 unknown facts about fats.
Average a common person buys 1 g every day excess fat
. In reality, people gain more body fat. More attention should be paid to nutrition and physical activity. Draw conclusions: The higher your fat intake, the sooner health problems will begin.
Fat cells live for ten years after a person's death. However, they die under the influence physical activity. The problem is that brain cells are constantly dying and being renewed, but if their place is taken fat cells, memory problems occur, especially in older people.
8. Source of calories
In fact, fat is an essential source of calories. necessary for the body. It is vital for maintaining all vital processes in the body. It is worth remembering that excess weight leads to health problems. The main rule is choice the right products with enough calories for the body to function.
7. Fat enhances flavor
Most preservatives and flavor enhancers are based on fat. When you mix them with food, it acquires a pleasant and alluring aroma and taste. If you like to cook, try adding meat or animal fat to the dish; the smell and taste will immediately change.
Fat is a kind of absorbent for vitamins. People who regularly take vitamins notice that after eating, the effect of the vitamins is felt weaker. Especially if the vitamins are in soluble form.
5. Women need fat more than men.
First of all, women's greater need for fat is associated with nature. A woman is a mother, in order to conceive a child, the body requires strength to bear the child and grow it in the womb, the body burns calories and fats, and finally, after the birth of the child, the woman breastfeeds, and the basis of milk is lactose and fat. The fat reserves in a woman's body are explained by the fact that the body saves energy for the expectant mother. This is why many women lose weight after breastfeeding.
There are two types of fat. They are figuratively called good and bad. Good fat classified as unsaturated fats, such fats are essential to the human body. They are found in lean white meat and steamed foods, such as fish. Bad fats are fatty meats, chicken skin or dairy products. Consumption of these foods leads to high cholesterol and heart problems.
Since fat contains high level calories, they are stored in energy reserves. Consuming 1 gram of fat equals 9 calories.
2. Fat storage
The fat needed for health is stored in the muscles, bone marrow and organs nervous system. It is simply necessary for the production of hormones and increased immunity. Subcutaneous fat is an indicator that it is time to lose weight. Fat is found in foods that increase muscle mass.
Women should maintain between 13 and 17% body fat, which are usually stored in the hips, chest, thighs and abdomen. In men, fat is stored in the abdomen. They should maintain a body fat percentage of 3 to 5%, which is significantly less than for women.
Fat is considered the culprit of many ills. Doctors and scientists advise reducing fat intake or eliminating it from the diet altogether. Of course, for those who are obese or have chronic diseases, it is better to listen to this advice. However, the rest of us would be foolish to give up fat. Let's find out more about them with the facts below.
1. Consumption of fats does not necessarily lead to their deposition in the body.
Many people think that consuming fat will definitely affect their figure in the form of deposits on the waist, hips and abdomen. If you eat more than your body requires, then yes, this problem can arise. For example, if you consume starchy carbohydrates in unlimited quantities, you can expect an increase in insulin levels, and then fat will be deposited. But if you eat evenly consuming fats and proteins, then this problem can be avoided. In everything you need to know when to stop.
2. No need to avoid nuts
Nuts contain useful forms fats - monounsaturated fats, which help you feel full faster, but also increase healthy cholesterol. Nuts do not have any effect on weight gain, because you can’t eat a lot of them due to their satiety, and besides, they are poorly digested by the body. Consequently, the cell walls of nuts are not easily destroyed during chewing. This means that they pass through the body in transit and do not release all their fat.
3. There is no need to completely eliminate saturated fats from the body.
It has always been believed that saturated fats are the enemies of health, so they were advised to be excluded from the diet. But today it has become clear that moderate consumption of saturated fat does not cause any harm. And some of them even need to be included in a healthy eating program.
Virgin coconut oil is one of the healthy sources of saturated fat. It contains lauric acid, which is found nowhere else except in breast milk. It is a powerful immune stimulant. It is recommended to fry foods in coconut oil.
4. Just because a product label says “no trans fats” doesn’t mean they aren’t there.
Many manufacturers believe that if a product contains a very small amount of an ingredient, then there is no need to list it on the label. It happens that a product contains only 0.5 g of trans fat, but you will not find it among the ingredients on the packaging. After eating several servings of this product, you will not even know that you have eaten enough of this harmful ingredient.
5. Nutrients from vegetables without fat are less absorbed
Studies have shown that salad dressed with fat or sauce with fat is much better absorbed by the body and receives more essential nutrients - carotenoids. If you constantly eat salads without fat, then carotenoids will not be absorbed by the body at all. They are responsible for red, yellow, orange and green colors and are important for preventing many diseases. So that the body absorbs everything nutrients from vegetables, eat them with healthy fats.
6. Olive oil first spin not suitable for frying
Although it contains healthy monounsaturated fats, it high temperatures loses its properties. It is better to use it for dressing salads or marinating meat. Olive oil is very delicate and spoils quickly, so it should be stored in a dark glass container with a tightly closed lid to avoid oxidation and preserve all its beneficial properties.
7. Fats have many functions in the body.
Without fats, our body and our organism cannot live. Here are a few reasons for this:
The brain needs fats. About 60% of the dry weight of the human brain is fat. Healthy nerve cells contain fats - docosahexanoic acid;
Sexual hormones are formed with the help of fats;
Fatty acids are essential for healthy skin and hair;
Fats are involved in metabolism, functions immune system, help stabilize blood sugar.
One of the biggest myths modern humanity- harmfulness of fats. Fat has become enemy number one. People spend dollars, rubles, euros, etc. to buy low-fat cookies, low-fat cola, tablets that can interfere with the absorption of fats, tablets that dissolve fats. People are on all sorts of fat-free diets.
But... In countries that are prosperous in all respects, the number of people suffering from obesity is steadily growing. The number of people suffering from cardiovascular diseases and diabetes mellitus, that is, diseases largely associated with excess weight. The war on fat continues...
So what's wrong?
Fact 1: Fats are good for you
The first and main mistake is to assume that all fats are the same; giving up all fats is a good thing. However, the education of the population is quite high, now many people know that unsaturated fats (mainly vegetable fats) are healthy. And the harmful ones are saturated ones (mainly animals).
Let's figure this out.
Saturated fats - structural components cell membranes, participate in the biochemistry of the body. That's why complete failure from them will lead to irreversible changes in health. Another thing is that their consumption must correspond age indicators. Children and adolescents need them in sufficient quantity, their consumption can be reduced with age.
Unsaturated fats - reduce the level of “bad” cholesterol, are necessary for the body to absorb certain vitamins (fat-soluble), and participate in metabolism. That is, the body also needs these fats.
A quick observation: saturated fats are solid, unsaturated fats are liquid.
According to physiological indicators for the average person, the ratio of saturated - unsaturated fats should be 1\3:2\3. Eating healthy fats is essential!
Trans fats are definitely harmful. They are also found in nature (for example, in natural milk), but for the most part they are formed from other (vegetable) fats, through hydrogenation (a method of processing fats to give them a solid form).
Fact 2: Body fat is not the result of eating fat.
What?! Of course, if you simply increase your fat intake without reducing other foods, you excess weight dial. The basis of maintaining a normal weight is balance. You should burn as many calories as you consume.
But diets with sharp restriction calorie intake can also lead to sudden weight gain after withdrawal. Why? The body received a command: hunger. This means we need to accumulate fats in reserve. Therefore, all food is processed and goes to the “depot” - body fat. At the same time, you may faint from hunger. Processed carbohydrates are stored in fat reserves.
Studies show that if a person is on a low-calorie, low-fat diet, then the few kilograms lost with great difficulty come back, even if you continue to “sit” on this diet.
In addition, people who consume low amounts of fat are prone to obesity.
And observations of patients in the USA revealed a picture that a decrease in the amount of fat from 40% (which is considered normal) to 33% in the diet is accompanied by an increase in overweight people.
Remember that unsaturated fats are involved in metabolism. The protein: fat: carbohydrate ratio for an adult should be approximately 14%: 33%: 53%.
Conclusion: An increase in unsaturated fats in food while maintaining the same calorie content will not lead to weight gain, but will contribute to improved health through metabolism.
Fat has always been regarded as a component of food that is harmful to the body, and some nutritionists are of the opinion that it is better to limit the intake of fat. But are fats really that bad for us?
In fact, fats perform several very important functions for our body, and first of all, fat is an important supplier of energy for us. We can highlight the fact that 1g of fat supplies more calories than proteins and carbohydrates in double quantity. The body does not burn all fats at once, but puts some of them in storage as a reserve to be used in the future as needed. We bring you information about fats that will help you look at fats in a new way.
Why is fat necessary for our body?
Fats supply essential fatty acids for the functioning of our body, which are involved in metabolism and are energy suppliers. In addition, fats are part of cell membranes, for example, nerve cells have membranes that are 60% fat. Thus, we can distinguish several important functions fat:
Fats are suppliers of energy material - approximately 30% of energy comes from fats,
By forming subcutaneous fatty tissue, they protect organs and tissues from mechanical damage, and also prevent heat loss,
They are carriers for vitamins A, D, E, K, as well as minerals, since without fats their absorption in the body is impossible,
They are part of cell membranes (mainly cholesterol). Without them, the cell loses its function and collapses,
Fats produce female sex hormones, which is especially important in postmenopause, when ovarian function has practically disappeared. They also play an important role during the reproductive period, since they support hormonal background at the proper level. If the level of adipose tissue in the body is below 10-15%, then hormonal imbalance up to the cessation of the menstrual cycle,
Omega-6 unsaturated acid(aka arachidonic acid) is involved in the activation of blood coagulation and anticoagulation systems.
Almost 35% daily diet must consist of fats. Wherein significant role plays a type of fat.
Which fats are healthy and which are not?
Depending on the chemical structure Fats are divided into saturated and unsaturated fatty acids. Saturated fatty acids contain a large number of hydrogen ions and are part of food products of animal origin. These are precisely the fats that are deposited on the stomach, thighs, and buttocks. This is peculiar energy reserve body. Saturated fats hinder growth muscle mass because they reduce the effect of insulin. But at the same time, they are the basis for the production of testosterone. When they are excluded from food, the level of this hormone, important for men, also decreases. The same can be achieved by consuming them excessively. Therefore, they are also important for the body, but in moderation.
Unsaturated fatty acids (Omega-3 and Omega-6) contain few hydrogen ions and are found primarily in animal products, such as olive oil or vegetable oil, fish oil. These fats are not stored in the body, but are completely burned. They are a beneficial nutritional component for the body and a raw material for the production of hormones.
There are also so-called trans fats, or artificial fats. They are filled with hydrogen ions and are found in candies and cookies, as well as in foods fast food(fast food). They are used primarily for food storage and increase the risk of developing oncological diseases and diseases of the cardiovascular system.
Omega-3 and Omega-6 are unsaturated fatty acids.
Of all types of fats, these fatty acids are the most valuable for our body. They are found in sunflower and corn oils, and rapeseed oil contains them in an ideal ratio.
Omega-3 fatty acids that are beneficial for the body are also found in flaxseed, nut and soybean oils. Salmon, mackerel and herring also contain them in sufficient quantities.
Omega-3 and Omega-6 fatty acids:
Reduce the risk of developing atherosclerosis, thus preventing the development of cardiovascular diseases
Reduces cholesterol levels,
Strengthens the walls of blood vessels,
Reduce blood viscosity, thus preventing the development of blood clots,
Improve blood supply to organs and tissues, restoration of nerve cells.
Ideally, you need to mix saturated and unsaturated fats, for example, season meat dishes and salads with canola oil.
Which is better, margarine or butter?
Unlike butter, margarine contains more unsaturated fatty acids. But according to new teachings, this does not mean that the oil is more harmful. In terms of calories, both products are almost equal. But margarine contains harmful trans fats, which contribute to the growth of several diseases.
If you are a fan of margarine, then it is better to choose high-quality types with low content solid fats.
Do fats lead to obesity?
Although fat contains more calories, there is no proven link between fat intake and increased weight.
Excess calories lead to obesity: those who consume more calories than they burn gain weight. Food containing sufficient amounts of fat satiates us for a long period and allows us to eat less.
Those who, on the contrary, try to save on fats, often eat more carbohydrates. Cereal products such as White bread And pasta increase blood sugar levels, and with it insulin, which leads to the growth of adipose tissue. In addition, saturation of the body occurs quickly, but does not last long, resulting in more frequent food consumption.
Loading...