Nutrients proteins fats carbohydrates. Nutrients. Proteins, fats and carbohydrates. Breakthrough bream caviar

Along with proteins, carbohydrates and fats, a balanced human diet should contain vitamins, minerals, trace elements and adequate amounts of water. In addition, it is desirable to eat every day coarse-fiber products of plant origin (for example, fiber), which are not digested and, due to their ability to swell, stimulate intestinal motility. For a practically healthy adult, daily protein intake should be 10-15% of the total daily caloric intake of food (0.8 g per 1 kg of body weight, or -56 g for a man with a body weight of 70 kg). Another 25-30% (-78 g) is fat and the remaining 55-60% is carbohydrates. Thus, carbohydrates are the main source of energy for the body.

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The main purpose of proteins is to provide the body with the amino acids required for the biosynthesis of the body's endogenous proteins. Human body is unable to synthesize eight of the 20 naturally occurring amino acids needed to make its own proteins. These amino acids, called "essential amino acids", include leucine, lysine, methionine, phenylalanine, isoleucine, valine, threonine, and tryptophan. Some other amino acids become essential under special conditions:

Tyrosine and cysteine ​​- in premature infants and patients with cirrhosis of the liver;
- histidine - with uremia;
- arginine - for violations of the immune system. With the exception of lysine, which is absent or deficient in many plant foods, essential amino acids are found in proteins of both plant and animal origin.

Fats (lipids)

Fats are an energy-rich nutrient (see above: Nutrients for Energy). They serve primarily as sources of energy, and also provide its storage. In addition, fats contain essential fatty acid(polyunsaturated fatty acids found in vegetable oils, mainly linoleic and linolenic acids). The absence of these substances in the diet leads to manifestations of deficiency. Lipids are present in high concentrations, in particular, in the genitals; fats are required to form the lipid components of cell membranes. Fats contain cholesterol, which is involved in the formation of the structure of cells (cell membranes) and serves as a precursor of some hormones. Finally, fats are solvents that ensure complete absorption of fat-soluble vitamins (such as vitamins A and E) from the gastrointestinal tract.

Fats are represented in the diet mainly by triglycerides. These are neutral fats; each molecule consists of three fatty acids linked to the trivalent alcohol glycerol. The most common fatty acids are palmitic, stearic, oleic and linoleic. Animal fats are predominantly saturated fatty acids (the exception is marine fish), while vegetable fats are high in unsaturated fatty acids (the exception is coconut oil).

Carbohydrates

Carbohydrates are the main source of energy for many organisms. In the human diet, the combination of monosaccharides (eg glucose = dextrose), disaccharides (eg lactose = milk sugar) and polysaccharides (eg starch) is most important. Monosaccharides in our diet are found mainly in honey and fruits, disaccharides - in milk and in products with common sugar used in home cooking (sucrose, cane sugar), polysaccharides - in plant products (starch) and animal origin (glycogen) . Carbohydrates can be stored in the body only in small quantities. For example, during fasting, the entire supply of glycogen in the liver and skeletal muscles (approximately 300-400 g) is consumed within a day and a half. Because of their sweet taste, simple sugars (monosaccharides and disaccharides) are very popular and widely used. They can protect food from spoilage and are therefore used in canning. At the same time, simple sugars create a significant load on the pancreas. Small molecules quickly enter the blood vessels, and blood sugar levels rise sharply. To lower blood sugar levels, the pancreas must secrete large amounts of insulin, and as a result, sugar levels drop to such low levels that there is a strong feeling of hunger and fatigue. With a new portion of sugar, its level in the blood again rapidly increases. A high-sugar diet leads to large fluctuations in blood sugar levels, with corresponding performance swings. In addition, simple sugars have almost no nutritional value, they are "empty calories". Whole grains (containing starch + vitamins + fiber) provide a longer maintenance of blood sugar levels, and do not cause its sharp fluctuations.

Food is a natural source of basic nutrients (proteins, fats, carbohydrates), as well as vitamins, mineral salts, water, etc., necessary for the body.

For normal life, a person needs a certain ratio of B, F, U, microelements and vitamins, minerals. The variety of food products consists of combinations of nutrients B, F, U, vitamins, minerals and water. Ratio B, W, Y- 1:1,2:4. This makes it possible to carry out the rationing of the daily calorie content of the diet at the expense of proteins of 15% of the daily calorie content (1/2 proteins of animal origin). Fats 30% of daily calories (70-80% animal fat). The energy share of carbohydrates is 55%. To reduce body weight, you need to reduce your carbohydrate intake. With heavy physical work, many proteins are destroyed, which means it is necessary to increase their intake with food. In addition, increase the proportion of fats and carbohydrates as calorie providers.

In the human body, processes of oxidation (combination with oxygen) of various nutrients - proteins, fats, carbohydrates - are continuously occurring, which are accompanied by the formation and release of heat. This heat is necessary for all life processes, it is spent on heating the inhaled air, on maintaining body temperature. Thermal energy also provides the activity of the muscular system. The more muscle movements a person performs, the more he produces losses, which require more food to cover.

The need for more food is expressed in heat units - calories. The calorie content of food is the amount of energy that is formed in the body as a result of the assimilation of food. A calorie is the amount of heat required to heat 1 liter (large calorie) and 1 ml (small calorie) of water at a temperature of 15 degrees Celsius by one degree. Each gram of protein and each gram of carbohydrates of any food, when burned in the body, forms heat equal to 4 kcal in quantity, and when 1 g of fat is burned, 9 kcal is formed.

Daily energy consumption within the same age group is individual. It depends on the physical development of a person, the state of his nervous and endocrine systems, the intensity of movements, labor, and the general condition of the body.

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A child under the age of 3 years is growing rapidly and should receive relatively more complete proteins in food than an adult. However, it does not follow from this that the more protein the child receives, the better. Protein is not deposited in the body in the form of reserves. Excess protein cannot be used by the body, and the processing of protein and the excretion of its decay products from the body require an excessive expenditure of energy.

Fats

The main sources of fat for a child are: milk, milk formulas, egg yolk, butter and vegetable oil. Food fats are necessary for a child, as they are part of the cells of the body, take part in metabolism, and are a source of heat and energy.

With insufficient intake of fats in the body of a child, there is a lag in physical development, eczema, neurodermatitis, the severity of anemia and rickets is aggravated, and immunity is reduced.

Carbohydrates

Excess intake of carbohydrates contained in bread, potatoes, cereals can lead to fat formation. An important impact on carbohydrate metabolism provides fiber. Fiber in the body is not absorbed, but its insufficient intake can lead to the development of diabetes, atherosclerosis, coronary disease, chronic constipation, and tumors. Therefore, it is necessary to include vegetables and fruits in the diet of children, and with age, wholemeal bread (“Doctor's”, “Health”).

Minerals and trace elements

Mineral salts are necessary for a growing organism as a plastic material for the formation of bone tissue, as regulators of metabolic processes and hematopoiesis processes. The composition of body tissues includes macroelements (potassium, calcium, sodium, phosphorus, chlorine) and microelements (magnesium, copper, manganese, iodine, zinc, iron, fluorine, etc.). The amount of mineral salts in food products is different. Calcium salts are rich in milk, dairy products, egg yolk, nuts, beans, vegetables. Phosphorus salts are rich in meat, cheese, egg yolk, oatmeal, beans, flour. Meat, liver, fish, fish caviar, egg yolk, oatmeal contain iron salts. These same foods are also rich in copper.

vitamins

For a growing organism, the content of various vitamins in food plays an important role. Distinguish between fat and water soluble vitamins.

Fat-soluble vitamins are distinguished by their ability to accelerate metabolic processes in certain tissues: retinol (vitamin A) - in the retina, calciferols (vitamin D) - in bone tissue, tocopherols (vitamin E) - in muscle tissue, phylloquinones (vitamin K) - in the coagulation system blood.

Water

Water is just as important a component of nutrition as all of the nutrients listed above. Every day a certain amount of water is vital for the body to digest food, remove toxins and maintain normal body temperature. From a medical point of view, the loss of 7% of the total amount of water is a physiological disaster for humans.

The body's need for water is about 2-2.5 liters per day.

The human body consists of proteins (19.6%), fats (14.7%), carbohydrates (1%), minerals (4.9%), water (58.8%). He constantly spends these substances on the formation of energy necessary for the functioning of internal organs, maintaining heat and carrying out all life processes, including physical and mental work. At the same time, the restoration and creation of cells and tissues from which the human body is built, the replenishment of expended energy due to substances from food take place. These substances include proteins, fats, carbohydrates, minerals, vitamins, water, etc., they are called food. Consequently, food for the body is a source of energy and plastic (building) materials.

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These are complex organic compounds of amino acids, which include carbon (50-55%), hydrogen (6-7%), oxygen (19-24%), nitrogen (15-19%), and may also include phosphorus, sulfur , iron and other elements.

Proteins are the most important biological substances of living organisms. They serve as the main plastic material from which the cells, tissues and organs of the human body are built. Proteins form the basis of hormones, enzymes, antibodies and other formations that perform complex functions in human life (digestion, growth, reproduction, immunity, etc.), contribute to the normal metabolism of vitamins and mineral salts in the body. Proteins are involved in the formation of energy, especially during a period of high energy costs or with insufficient amounts of carbohydrates and fats in the diet, covering 12% of the body's total energy needs. The energy value of 1 g of protein is 4 kcal. With a lack of proteins in the body, serious disorders occur: a slowdown in the growth and development of children, changes in the liver of adults, the activity of the endocrine glands, blood composition, a weakening of mental activity, a decrease in working capacity and resistance to infectious diseases. Protein in the human body is formed continuously from amino acids that enter the cells as a result of the digestion of food protein. For the synthesis of human protein, food protein is needed in a certain amount and a certain amino acid composition. Currently, more than 80 amino acids are known, of which 22 are the most common in foods. Amino acids according to their biological value are divided into irreplaceable and non-essential.

indispensable eight amino acids - lysine, tryptophan, methionine, leucine, isoleucine, valine, threonine, phenylalanine; children also need histidine. These amino acids are not synthesized in the body and must be supplied with food in a certain ratio, i.e. balanced. Interchangeable amino acids (arginine, cystine, tyrosine, alanine, serine, etc.) can be synthesized in the human body from other amino acids.

The biological value of protein depends on the content and balance of essential amino acids. The more essential amino acids it contains, the more valuable it is. A protein that contains all eight essential amino acids is called complete. The source of complete proteins are all animal products: dairy, meat, poultry, fish, eggs.

The daily intake of protein for people of working age is only 58-117 g, depending on gender, age and the nature of the person's work. Proteins of animal origin should be 55% of the daily requirement.

The state of protein metabolism in the body is judged by the nitrogen balance, i.e. according to the balance between the amount of nitrogen introduced with food proteins and excreted from the body. Healthy adults with a healthy diet are in nitrogen balance. Growing children, young people, pregnant and lactating women have a positive nitrogen balance, because. food protein goes to the formation of new cells and the introduction of nitrogen with protein food prevails over its removal from the body. During starvation, diseases, when food proteins are not enough, a negative balance is observed, i.e. more nitrogen is excreted than it is introduced, the lack of food proteins leads to the breakdown of proteins of organs and tissues.

Fats

These are complex organic compounds consisting of glycerol and fatty acids, which contain carbon, hydrogen, oxygen. Fats are one of the main nutrients, they are an essential component in a balanced diet.

The physiological significance of fat is diverse. Fat is part of cells and tissues as a plastic material, used by the body as an energy source (30% of the total need

organism in energy). The energy value of 1 g of fat is 9 kcal. Fats supply the body with vitamins A and D, biologically active substances (phospholipids, tocopherols, sterols), give food juiciness, taste, increase its nutritional value, causing a person to feel full.

The rest of the incoming fat after covering the needs of the body is deposited in the subcutaneous tissue in the form of a subcutaneous fat layer and in the connective tissue surrounding internal organs. Both subcutaneous and internal fat are the main reserve of energy (reserve fat) and are used by the body during strenuous physical work. The subcutaneous fat layer protects the body from cooling, and the internal fat protects the internal organs from shock, shock and displacement. With a lack of fat in the diet, a number of disorders of the central nervous system are observed, the body's defenses weaken, protein synthesis decreases, capillary permeability increases, growth slows down, etc.

Human fat is formed from glycerol and fatty acids that enter the lymph and blood from the intestines as a result of the digestion of food fats. For the synthesis of this fat, dietary fats are needed that contain a variety of fatty acids, of which 60 are currently known. Fatty acids are divided into saturated or saturated (ie, saturated with hydrogen to the limit) and unsaturated or unsaturated.

Saturated fatty acids (stearic, palmitic, caproic, butyric, etc.) have low biological properties, are easily synthesized in the body, adversely affect fat metabolism, liver function, and contribute to the development of atherosclerosis, as they increase blood cholesterol. These fatty acids are in large numbers are found in animal fats (lamb, beef) and in some vegetable oils (coconut), causing their high melting point (40-50°C) and relatively low digestibility (86-88%).

Unsaturated fatty acids (oleic, linoleic, linolenic, arachidonic, etc.) are biologically active compounds capable of oxidation and addition of hydrogen and other substances. The most active of them are: linoleic, linolenic and arachidonic, called polyunsaturated fatty acids. According to their biological properties, they are classified as vital substances and are called vitamin F. They take an active part in fat and cholesterol metabolism, increase elasticity and reduce the permeability of blood vessels, and prevent the formation of blood clots. Polyunsaturated fatty acids are not synthesized in the human body and must be introduced with dietary fats. They are found in pork fat, sunflower and corn oil, fish fat. These fats have a low melting point and high digestibility (98%).

The biological value of fat also depends on the content of various fat-soluble vitamins A and D (fish fat, butter), vitamin E (vegetable oils) and fat-like substances: phosphatides and sterols.

Phosphatides are the most biologically active substances. These include lecithin, cephalin, etc. They affect the permeability of cell membranes, metabolism, hormone secretion, and blood coagulation. Phosphatides are found in meat, egg yolk, liver, dietary fats, and sour cream.

Sterols are a constituent of fats. In vegetable fats, they are presented in the form of beta-sterol, ergosterol, which affect the prevention of atherosclerosis.

In animal fats, sterols are contained in the form of cholesterol, which ensures the normal state of cells, is involved in the formation of germ cells, bile acids, vitamin D 3, etc.

Cholesterol is also formed in the human body. In normal cholesterol metabolism, the amount of cholesterol ingested and synthesized in the body is equal to the amount of cholesterol that decays and is excreted from the body. In old age, as well as with an overstrain of the nervous system, overweight, with a sedentary lifestyle, cholesterol metabolism is disturbed. In this case, dietary cholesterol increases its content in the blood and leads to changes in blood vessels and the development of atherosclerosis.

The daily rate of fat consumption for the able-bodied population is only 60-154 g, depending on age, gender, nature of the pile and climatic conditions of the area; of these, animal fats should be 70%, and vegetable - 30%.

To ensure proper nutrition, it is very important to maintain a balance in the intake of proteins, fats and carbohydrates. None of these substances can be eliminated from the daily diet without causing damage to the entire body.

Carbohydrates replenish the energy supply of the body and normalize the metabolism of proteins and fats. When combined with proteins, they are converted into a certain type of enzymes, hormones, the secretion of the salivary glands and a number of other important compounds.

Depending on the structure, simple and complex carbohydrates are distinguished. Simple ones are easy to digest and have low nutritional value. Their excessive use leads to a set of extra pounds. In addition, an excess of simple carbohydrates favors the growth of bacteria, leads to intestinal diseases, worsens the condition of teeth and gums, and provokes the development of diabetes.

In foods containing simple carbohydrates, as we see, there is practically no benefit. Their main sources are:

• sugar;
• white bread and pastries;
• any kind of jam and jam;
• pasta made from white flour.

It is better to refuse the use of such products at all, as they contribute to obesity in the shortest possible time.

It is better to give preference to simple carbohydrates contained in vegetables and fruits. It is very useful to eat watermelon, bananas, pumpkin, turnips in the morning.

Complex carbohydrates (or polysaccharides) contain a significant amount of fiber, which is essential for lowering blood cholesterol levels, preventing gallstones, and controlling appetite. Polysaccharides are able to saturate the body for a long time. Also among the positive properties of polysaccharides can be identified:

• providing the body (in addition to calories) with valuable nutrients, vitamins and trace elements;
• slow processing by the body, as a result of which the release of sugar into the blood occurs at a low rate;
• ingestion with liquid food, which improves the functioning of the digestive system.

What foods contain complex carbohydrates? Healthy carbohydrate foods include:

• oatmeal and buckwheat;
• brown rice;
• peas, beans and lentils;
• some vegetables and fruits;
• greens;
• nuts.

Lack of polysaccharides in the body can cause weakness, drowsiness and bad mood. However, you should not get involved in eating foods containing complex carbohydrates either: in an immoderate amount, they can also lead to the formation of excess weight.

It is not necessary to exclude carbohydrate foods from the diet, even for people who are prone to fullness. We recommend that you simply follow a number of rules that prevent the transformation of carbohydrates into fat:

• Eat small meals, but often.
• Monitor the amount of carbohydrates consumed: no more than 50–70 g per serving.
• Eliminate the use of sweets, packaged juices, soda, pastries, and give preference to legumes and whole grain dishes.
• Actively engage in physical education and sports, spending calories from carbohydrate foods.

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Protein is a vital substance. Protein contributes to the growth of muscles and muscle tissue, takes part in metabolic processes. Proteins are digested and broken down into amino acids, which the body uses to make its own protein. Plant-based protein sources offer a number of benefits:

• in addition to protein, they contain carbohydrates, useful vitamins and minerals, which are very well absorbed;
• they do not contain saturated fats, cholesterol, hormones and antibiotics that adversely affect the work of all body systems.

Vegetable protein contains the following products:

• peas;
• beans;
• Rye bread;
• rice, pearl barley and buckwheat.

Excessive consumption of protein foods threatens to overload the liver and kidneys, which occurs due to protein breakdown products. Also, an excessive content of proteins in the body is fraught with putrefactive processes in the intestines.

Fats

Fats are a source of energy. In addition, they are necessary for the successful absorption of a number of vitamins by the body and serve as a supplier of essential fatty acids.

There are two types of fats: saturated and unsaturated. Saturated fats contribute to the accumulation of cholesterol and the formation of atherosclerotic plaques. Unsaturated fats, when consumed in moderation, can burn fat and prevent blood clots.

Unsaturated fatty acids are found in vegetable fats, they do not contain cholesterol, but on the contrary, they help cleanse the body of it, preventing thrombosis and atherosclerosis, promote the separation of bile and normalize bowel function. This type of fat is easily digested and digested quickly enough.

Unsaturated fats are found in the following plant foods:

• sunflower, olive, linseed and corn oil;
• nuts and seeds;
• olives and olives.

Fats are essential for the body. If they are completely excluded from the diet, then a number of negative consequences may appear:

• dry skin;
• bad mood and depression;
• chronic fatigue and drowsiness;
• constant feeling of cold;
• inability to concentrate.

It should be mentioned that the absence of fat in the diet will not lead to weight loss, but, on the contrary, may result in the appearance of extra pounds. The fact is that the body will compensate for the lack of fat using proteins and carbohydrates. And eating fats and simple carbohydrates in large quantities, you are equally at risk of gaining excess weight.

With excessive consumption of fats, the absorption of protein, magnesium and calcium worsens, problems arise with digestive system. Proper fat metabolism will ensure the use of vitamins contained in vegetables and fruits.

Balance of proteins, fats and carbohydrates

Proteins, fats, carbohydrates contained in food should be counted for the consumption of sufficient and necessary amounts.

To control weight, you need to know what is the optimal daily intake of BJU. The most successful ratio of proteins, fats and carbohydrates (BJU) is 4: 2: 4. It is necessary to note the daily rate of each of the components:

• proteins - 100-120 grams, with intensive physical labor, the norm increases to 150-160 grams;
• fats - 100-150 grams (depending on the intensity of physical activity during the day);
• carbohydrates - 400-500 grams.

Note that 1 gram of protein and carbohydrates contains 4 kcal, and 1 g of fat - 9 kcal.

The basics of proper nutrition

And fats, and carbohydrates, and proteins are necessary for the full functioning of all vital systems of the body. To summarize the above and add some new information, we suggest that you familiarize yourself with the recommendations that will allow you to ensure the right approach to nutrition:

• Study the daily intake of BJU and try not to exceed it, an excess (as well as a lack) of substances will negatively affect your health.
• Consider your weight, lifestyle and physical activity when calculating the norm.
• Not all proteins, fats, and carbs are beneficial: opt for foods that contain complex carbohydrates and unsaturated fats.
• Eat fats and complex carbohydrates in the morning, and proteins in the evening.
• Products containing proteins, fats and complex carbohydrates, subject to heat treatment only in the form of steaming, stewing or baking, but in no case frying in oil.
• Drink more water and eat fractionally, as this diet can provide better absorption of substances.

Knowing about proteins, fats and carbohydrates will help you create the right and balanced menu for every day. A properly selected diet is a guarantee of health and well-being, productive working hours and good rest.

TRAINING MATERIAL FOR SELF-EDUCATION

Nutrition provides the most important function of the human body, supplying it with the energy necessary to cover the costs of life processes. Renewal of cells and tissues also occurs due to the intake of "plastic" substances - proteins, fats, carbohydrates, vitamins and mineral salts - into the body with food. Finally, food is the source of the formation of enzymes, hormones and other metabolic regulators in the body. To support the normal flow of energy, plastic and catalytic processes, the body requires a certain amount of various nutrients. The metabolism in the body, the structure and functions of cells, tissues, and organs depend on the nature of nutrition. Proper nutrition taking into account the conditions of life, work and life, it ensures the constancy of the internal environment of the human body, the activity of various organs and systems and, thus, is an indispensable condition for good health, harmonious development, high efficiency. Proper nutrition is considered to be such that ensures the normal functioning of the body, a high level of efficiency and resistance to adverse factors. environment, the maximum duration of active life. The biological value of food is determined by the content of essential nutrients necessary for the body - proteins, fats, carbohydrates, vitamins, mineral salts.

NUTRIENTS AND THEIR SIGNIFICANCE IN HUMAN NUTRITION

The importance of nutrients in the life of the body is characterized by I.M. Sechenov, who believed that "... to trace the fate of nutrients in the body means to know the essence of life processes in their entirety."

All food substances according to their purpose can be divided into plastic, energy and regulatory. Among plastic substances, proteins are of primary importance, although minerals and fats also take a certain part in plastic processes.

Carbohydrates are the main energy source. Due to carbohydrates, the need for energy necessary for muscular labor and physical work is satisfied. To some extent, fats and proteins can serve as a source of this energy.

Regulatory substances include mainly vitamins and minerals, the function of which is to regulate and analyze metabolic processes.

PROTEINS.

Proteins are vital nutrients, without which life, growth and development of the body is impossible. A sufficient amount of proteins in the diet and their high quality allows you to create optimal conditions internal environment for the normal functioning of the organism, its development and high performance. Proteins should be the main component of the diet, determine the nature of the entire diet. Against the background of a sufficient level of proteins, the most complete manifestation in the body of biological properties and other nutritional components is noted.

Proteins are the main component of the protoplasm of cells, they are part of the nucleus and intercellular substances, therefore they are used to build new cells and restore dead ones. Of particular importance are specific proteins that are part of enzymes, hormones, antibodies and other formations that perform a particularly important, complex and subtle function in the body. These proteins include globin, which is part of the hemoglobin of erythrocytes and performs the most important function of respiration, supplying tissues with oxygen. Myosin and actin provide muscle contraction. gamma globulins - form antibodies that protect against infections.

Proteins are used in the body mainly as a plastic material. Along with this, proteins are involved in the energy balance of the body, during periods of high energy expenditure or when food contains an insufficient amount of carbohydrates and fats.

Protein deficiency in the body causes severe metabolic disorders, edema, fatty liver and a number of other severe changes. Protein deficiency diseases include a special disease called kwashiorkor. Kwashiorkor develops as a result of a predominantly carbohydrate diet with insufficient use of complete protein sources.

The disease is characterized by clinical manifestations characteristic of alimentary dystrophy - growth retardation, weight and development of children, discoloration of the skin and mucous membranes, diarrhea, swelling, etc.

The mortality rate for untreated severe kwashiorkor can be as high as 90%. An autopsy reveals fatty liver, atrophy of the intestines and pancreas. In the case of moderate severity, irreversible changes may remain - insufficient development and reduced resistance to adverse factors.

With insufficient intake of proteins with food in the body, a violation of the process of deamination, transamination and synthesis occurs, which is due to the destruction of the corresponding enzyme systems due to the insufficiency of the specific proteins that make up their composition.

Protein deficiency affects the immunobiological properties of the organism, its reactivity and susceptibility to various diseases.

Against the background of insufficient protein nutrition, outbreaks of many infectious diseases. There are known outbreaks of dysentery and typhus, which have become especially widespread among the starving contingents.

Significant disturbances under the influence of protein deficiency occur in the endocrine glands. The general quantitative insufficiency of proteins and their qualitative inferiority lead to significant changes in the endocrine glands (genital, pituitary, adrenal glands) and a decrease in their functional abilities.

The formation of choline in the liver is disrupted, resulting in fatty infiltration of the liver. Increased formation of fat in the liver is associated with a lack of proteins containing methionine.

The lack of proteins in the diet entails a weakening of the conditioned reflex activity and the processes of internal inhibition. With protein deficiency, changes in the chemical composition and morphological structure of bones occur. When the protein content in the diet is reduced to 3.5-1.7%, bone growth stops, the amount of calcium in them sharply decreases and the amount of magnesium increases. As a result, the normal ratio of Ca and P is disturbed, the excretion of Ca from the body increases.

Thus, the changes that occur in the body under the influence of protein deficiency are very diverse and, apparently, cover all of its systems. The lack of protein in the diet negatively affects the growth of children, the function of the cerebral cortex, leads to a decrease in the formation of antibodies, hemoglobin, hormones, enzymes.

The nutritional value of various food proteins is not the same and depends on their digestibility (digestibility and absorption) and amino acid composition. The amino acid composition determines the extent to which absorbed amino acids are utilized by body tissues.

Some amino acids cannot be synthesized in the body and must be supplied ready-made as part of food proteins - essential amino acids. These amino acids are of particular value, because. are used for the synthesis and formation in the body of specific proteins, secrets and hormones. These include methionine, lysine, tryptophan, phenylalanine, leucine, isoleucine, threonine, valine.

For children, independent amino acids are also arginine and histidine.

Proteins are complete if all independent amino acids are safely balanced in them. The complete exclusion of one of the independent amino acids leads to a violation of protein balance and limited use the body of the whole complex of amino acids.

The importance of essential amino acids is not limited to their participation in the synthesis of tissue proteins. Each of them, in addition, performs important and complex functions in the body. In non-animal experiments, the role of individual amino acids was studied, and data of interest to clinicians were obtained.

Lysine, tryptophan, argipin are growth factors and are necessary for growth. With a lack of cystine in food, other amino acids are absorbed worse, hair growth is delayed, the formation of insulin in the body, and leukopenia develops. With an excessive content of cystine, leukocytosis is observed, degenerative changes occur in the kidneys. These changes can be prevented by fortifying food with thiamine and cholic acid.

Phenylalanine, leucine and isoleucine play an important role in thyroid and adrenal function. Arginine is associated with the function of the gonads. Some amino acids are associated with hematopoiesis. Thus, a lack of lysine in the blood leads to impaired hematopoiesis, the number of red blood cells and the content of hemoglobin in it decrease. Tryptophan and histidine have a great influence on the synthesis of hemoglobin. The lack of valine leads to impaired coordination of movements.

Methionine - used in the body for the synthesis of choline, affects the metabolism of fats and phosphatides in the liver, normalizing its condition. With a high level of methionine, the biological effect of vitamin B 12 and folic acid is most fully manifested. Methionine also plays an important role in the function of the adrenal glands and is necessary for the synthesis of adrenaline. There is evidence of the protective value of methionine in radiation injuries and poisoning with some industrial poisons.

An unsurpassed source of methionine is cottage cheese, which is widely included in the practice of therapeutic and preventive nutrition. Studies have shown that adding 400 gr. fresh cottage cheese had a very positive effect on the recovery time of patients with dysentery, especially in chronic forms of the disease. A lot of methionine is found in eggs, pike perch, crabs, cod, catfish, salmon, herring, stellate sturgeon, lamb. A lack of lysine causes growth retardation, circulatory disorders, bone calcification, and a decrease in hemoglobin in the blood.

Sources of phenylalanine, tryptophan and lysine are soy and pea flour, meat, fish, low-fat cottage cheese, eggs. Cornmeal is also rich in leucine and isoleucine.

With an increase in histidine in food in the tissues of the body, the activity of a complex of enzymes called histidase increases, the content of erythrocytes, leukocytes in the blood, carnosine in muscles and histimine in tissues increases, and blood pressure somewhat decreases. Under the influence of an excess of histidine, resistance to ionizing radiation increases: leukopenia develops more slowly, the ability of tissues to absorb oxygen is preserved. Histidine is rich in soy and pea flour, cottage cheese, meat.

The study of the role of individual amino acids in nutrition has led to a number of important general conclusions. It was found that the nature of the influence of the diet on the body depends not only on the absolute amount of individual amino acids present in it, but also on the ratio between individual amino acids, as well as other nutrients. Insufficient or excessive content of individual amino acids in food, as well as a violation of the optimal ratios between individual amino acids and other substances, leads to metabolic disorders and is the cause of the disease.

An important indicator Dietary protein quality can also be determined by its degree of digestibility, which reflects proteolysis in the gastrointestinal tract and subsequent absorption of amino acids. According to the rate of digestion by proteolytic enzymes, food proteins can be arranged in the following sequence: fish, dairy, meat proteins, proteins of bread and cereals.

The largest amount of protein is found in products of animal origin: various types of meat, fish, poultry, sausages, cottage cheese, cheese, eggs. The protein of these products has a high biological value. A lot of biologically valuable protein is found in plant products such as soybeans, peas, beans, and other legumes. The protein content of milk is relatively low, but due to its high biological value and high consumption level, this product should also be considered an important source of protein.

Bread and baked goods, cereals and pasta contain 5-12% protein. However, the protein of bakery products and cereals is deficient in a number of amino acids, primarily in the lens.

The condition of protein in the body depends on a number of conditions. It is necessary to introduce into the body a sufficient amount of carbohydrates and fats, which prevents the use of proteins to satisfy the energy expenditure of the body. Sufficient intake of vitamins is important to prevent increased breakdown of proteins.

The significant predominance of plant food over animal food, and even more so of vegetarian food, is one of the reasons for the decrease in the degree of use of proteins introduced with food.

An excess amount of fiber leads to a decrease in the digestibility of proteins, tk. accelerates the evacuation of food from the small intestine and amino acids, not having time to be absorbed, are brought out. In addition, the loose mass of fiber adsorbs a large amount of amino acids. It also prevents their absorption.

Fiber also adsorbs enzymes, reducing the intensity of cleavage of peptides, which are excreted from the body in an unsplit form.

The use of proteins is also reduced in cases where a large amount of food is introduced. Not all food introduced has time to digest.

The introduction of a significant excess of proteins cannot be considered rational either. Excessive introduction of proteins overloads the work of the digestive apparatus, increases the amount of protein breakdown products and putrefactive microorganisms, causes excessive deposition of fat in the liver, reduces the excitability of the nervous system, especially the cerebral cortex, disrupting the activity of the endocrine glands.

The need for protein depends on age, gender, character labor activity, climatic and national features.

According to the physiological norms adopted in our country, it is recommended that an average of 11-13% of the total energy value be provided in the diet of an adult due to protein (Table 3).

The total protein requirement in children is:

At the age of 1 to 3 years - 4 g / kg body per day;

From 3 to 7 years - 3.5-4 g / kg

From 8 to 10 years - 3.0 g / kg

From 11 and older - 2.5 - 2.0 g / kg

In the first year of life, 2.0 - 2.5 g / kg of body weight with natural feeding and 4 g / kg of body weight - with artificial feeding.

It is very important to provide the child with a sufficient amount of complete protein of animal origin, because. it contains the essential amino acids necessary for proper development.

So, animal proteins in relation to the total amount of proteins in the daily diet of a child of the first six months of life should be 90 - 99%, by the year - 80%, at the age of 1.5 - 2 years - 75%, 3-4 years - 70%, 5 -7 years - 65%.

FATS.

Fats are among the main nutrients and are an essential component in a balanced diet.

The physiological significance of fat is very diverse. Fats are a source of energy that surpasses the energy of all other nutrients. When burning 1 g of fat, 37.7 kJ (9.3 kcal) is formed, while when burning one gram of carbohydrates - 16.7 kJ (4.1 kcal). Fats are involved in plastic processes, being part of cells and their membrane systems.

Fats are solvents for vitamins A. E, and contribute to their absorption. A number of biologically valuable substances come with fats: phosphatides (lecithin), polyunsaturated fatty acids, sterols, tocopherons and other substances with biological activity. Fat improves the taste of food, increases its nutritional value, and promotes the digestibility of carbohydrates.

Insufficient intake of fat can lead to disruption of the central nervous system, weakening of immunobiological mechanisms, changes in the skin, kidneys, organs of vision, etc. Animals fed a low-fat diet showed less endurance and reduced life expectancy.

Essential, vital, irreplaceable components, including lipotropic anti-atherosclerotic action (polyunsaturated fatty acids, lecithin, vitamins A, E, etc.) have been identified in the composition of fat. Degenerative changes occur in the liver, kidneys, brain and other body systems if there is a lack of fat in the diet. . Experiments have shown that when fat is excluded from the feed, the development of growing animals stops, the occurrence of disorders in the main life-supporting systems of the body and the subsequent death of animals are noted, only the amount of fat corresponding to 10% of the total energy value of the diet ensures the preservation of animal life and can be considered as the minimum extremely allowable rate fat that ensures the survival of most animals. There is evidence of a contributing role of fat insufficiency in the development of nutritional dystrophy and other nutritional deficiencies. The view on fats as a powerful energy substance and a factor of pronounced protein conservation has long been defined. First world war among persons whose ration contained only 10 g of fat, there were cases of alimentary dystrophy. The study of the issue of the fat factor made it possible to put forward the position on the "biological fat minimum" and substantiate the idea of ​​the role of fat as an essential factor influencing cell function, the permeability of cell membranes and the state of intracellular elements.

As a confirmation of the above provision, the fact was cited that persons who received 6276.0 kJ (1500 kcal) and 60 g of protein in a daily diet with an extremely low fat content fell ill with "alimentary dystrophy" (edematous disease). After they were given 100 grams of lard a day, they quickly recovered; their edema completely disappeared.

The intensity and nature of many processes occurring in the body associated with the metabolism and transformation, as well as the absorption of nutrients, depend on the level of balance of fat with other nutrients.

By chemical composition fats are complex complexes of organic compounds, the main structural components of which are glycerol and fatty acids. Specific gravity glycerol in the composition of fat is negligible (10%). Fatty acids are essential for determining the properties of fats. The latter are subdivided into

(saturated) and unsaturated (unsaturated) fatty acids.

Essential nutritional factors include polyunsaturated fatty acids. For humans, essential fatty acids are linoleic and linolenic acid. Linoleic acid is converted in the body into arachidonic acid, and linolenic acid is converted into eicosapentaenoic acid. Arachidonic and eicosapentaenoic acids can also enter the body in small amounts as part of food products: the first - with meat products, the second - with fish.

The minimum daily human need for linoleic acid is 2-6 g. This amount is contained in 10-15 g of vegetable oil (sunflower, cottonseed, corn). To create some excess of essential linoleic acid, it is recommended to introduce 20-25 g of vegetable oil into the daily diet, which is approximately 1/3 of the total amount of fat in the diet. The content of linolenic acid in food is currently not strictly standardized. It is believed that it should come in amounts that are at least 10% of the amount of linoleic acid.

Increasing the amount of fat in the diet reduces the possibility of developing a linoleic acid deficiency.

Insufficient intake of linoleic acid with food causes in the body a violation of the biosynthesis of arachidonic acid, which is present in large quantities in its structural lipids, as well as prostaglandins. Arachidonic acid makes up 20-25% of all fatty acids of phospholipids of cellular and subcellular biomembranes.

To ensure the necessary fatty acid composition of the diet of a healthy person, it is necessary to maintain the ratio of 1/3 vegetable oils and 2/3 animal fats, using vegetable oils rich in linoleic acid (sunflower, cottonseed, soybean corn). Vegetable oils containing linoleic acid(linseed, hemp), it is rational to use in smaller quantities, simultaneously introducing large amounts of vegetable oils rich in linoleic acid. The source of PUFAs of the linolenic family is also the fats of marine (but not freshwater) fish (herring, flounder, mackerel, halibut, etc.). The inclusion of marine fish dishes in the diet provides the body with fatty acids of this family. Rapeseed and mustard oils, which have a lower nutritional value, should not be used as the sole source of vegetable fat in the diet: small amounts should be combined with complete oils, such as sunflower, corn.

For the elderly, as well as for elevated cholesterol levels in the blood serum, the ratio of vegetable oil and animal fats in the diet should be 1:1, i.e. half of the fat component should be introduced in the form of vegetable oil, provided that the total amount of fat is reduced.

Fish fats also have a hypotensive effect.

Margarine products have great opportunities for rationalization of fat nutrition. Margarine is a mixture of natural and hydrogenated vegetable and animal fats with the addition of skimmed milk, egg yolks, vitamins and various flavoring components.

Vitamins, sterols, phospholipids contained in fatty foods also play essential role in the body's metabolic processes.

Fatty foods make a significant contribution to providing the body with vitamins A and E.

Phospholipids are an essential component of both animal and unrefined vegetable fat products. They promote micellization of fat in the digestive tract. This process is necessary for the breakdown and absorption of food triglycerides. Phospholipids have a lipotropic effect, facilitating the transport of neutral fats from the liver. They are also important as stabilizing components of lipoproteins. Phospholipids are also used as stabilizers in fat pulses for parenteral nutrition. Unconditional preference should be given to the use of fatty products containing natural phospholipids.

However, some oils (corn, cottonseed) must undergo mandatory refining to help remove phosphatides. One of the undesirable moments in the production of margarines is the loss of phosphatides contained in the original oils.

Series are hydroaromatic sterols of complex structure. Fatty fats contain zoosterols, vegetable fats contain phytosterols. Wheat germ oil (13-17 g / 100 g of product), corn oil (6-7 g / 100 g of product) are distinguished by a high content of sterols.

Phytosterols have biological activity and play an important role in the normalization of fat and cholesterol metabolism. Of the phytosterols, gamma-phytosterol has the most biological activity, which is used for atherosclerosis for therapeutic and prophylactic purposes (it is found in arachidonic, sunflower, soybean, cottonseed, corn, and olive oils). Of the zoosterols, cholesterol plays an important physiological role.

The average physiological need for fat in a healthy person is about 30% of the total calorie intake. With heavy physical labor and, accordingly, a high caloric content of the diet that provides such a level of energy expenditure, the proportion of fat in the diet can be slightly higher - 35% of the total energy value. The normal level of approximation of fat intake is approximately 1-1.5 g/kg, i.e. 70= 105 g per day for a person weighing 70 kg. All fat contained in the diet is taken into account (both in the composition of fatty foods and the hidden fat of all foods)

The need for fats varies with age.

In the first six months of life, a child needs 6.5 - 6.0 g of fat / kg

In the second half of life - from 6 to 5.5 g / kg.

By the year of life - 5 g / kg

In children older than 1 year, the need for fat approaches the need for proteins and is 4 g / kg of body weight.

In old age, it is rational to reduce the proportion of fat to 25% of the total energy value of the diet and increase the proportion of vegetable fat to 80% of the total.

The need for fat varies depending on climatic conditions. In the northern climatic zone, it is defined as 38-40% of the total energy value of the diet, in the middle zone - 33% and in southern zone – 27- 28%.

CARBOHYDRATES.

The physiological significance of carbohydrates is mainly determined by their energy properties. Each gram of carbohydrate provides 4 kcal. The value of carbohydrates (U) as an energy source is determined by their ability to be oxidized in the body both aerobically and anaerobically. They are part of cells and tissues and are partially involved in plastic processes. Some carbohydrates have biological activity, performing specialized functions in the body (heparin, which prevents blood clotting in the vessels, hyaluronic acid, which prevents the penetration of bacteria through the cell membrane, etc.) Carbohydrates and their metabolites play an important role in the synthesis of nucleic acids, amino acids, mucopolysaccharides , coenzymes, etc. In the body, carbohydrates are deposited to a limited extent, the reserves are small. Carbohydrates are closely related to the measurement of fat. Carbohydrates are the main part of the diet. Due to them, about ½ of the daily energy value of the diet is provided. The consumption of carbohydrates is 400-500 g per day.

Satisfaction of the need for carbohydrates can be carried out at the expense of vegetable sources. In them (cereals, etc.) carbohydrates make up at least 75% of the dry matter. The need for carbohydrates can be met by sugar, which is a pure carbohydrate. The digestibility of carbohydrates is quite high: depending on the food product and the nature of the carbohydrate, it ranges from 85% to 98%. So, the coefficient of digestibility of carbohydrates in bread and cereal products is 94-96, vegetables - 85, potatoes - 95, fruits - 90, confectionery - 95, sugar - 99, milk - 98. The value of animal products as a source of carbohydrates is small. The main carbohydrate of animal origin is glycogen, which has the property of starch, contained in animal tissues in small quantities. Another carbohydrate - lactose (milk sugar) - in milk (5 g per 100 product).

Depending on the complexity of the structure, solubility, speed of assimilation, carbohydrates can be represented:

Simple carbohydrates (sugars) - monosaccharides: glucose, fructose, galactose; disaccharides: sucrose, lactose, maltose.

Complex carbohydrates - polysaccharides: starch, glycogen, pectin substances of fiber.

Simple carbohydrates: all of them are easily soluble in water, quickly digested.

MONOSACCHARIDES: Glucose is quickly and easily used in the body to form glycogen, to nourish brain tissue, working muscles, to maintain the required level of sugar in the blood and to create liver glycogen stores. Glucose is used as an energy source. Fructose has the same properties as glucose and can be considered as a valuable, easily digestible sugar. However, it is absorbed more slowly in the intestines and, entering the bloodstream, quickly leaves the bloodstream. It lingers in the liver (up to 70-80%) and does not cause blood glut with sugar. It is easily involved in metabolic processes, has low resistance, it is 2 times sweeter than sucrose, 3 times sweeter than glucose.

It has been established that with an excess intake of sugar, the conversion of nutrients into fat increases. Thus, the amount of incoming sugar can serve to a certain extent as a factor regulating fat metabolism. Excess sugar adversely affects the state and function of the intestinal microflora.

Galactose is not found in free form in foods. It is a product of the breakdown of the main carbohydrate in milk, lactose (milk sugar). Glucose and fructose are widely present in bee honey. In watermelons, all sugar is represented by fructose, the amount of which is 8%. Glucose and fructose are found in fruits and berries. In grapes and persimmons, all sugar is represented by glucose and fructose. Apples, pears, currants contain a significant amount of fructose.

DISACCHARIDES: Sucrose is of primary importance in human nutrition from disaccharides. During hydrolysis, sugar breaks down into 2 monosaccharide molecules - glucose and fructose. Its properties are close to monosaccharides. Another important disaccharide, lactose (milk sugar), is present only in milk and dairy products.

Sucrose - the source is cane and beet sugar.

Lactose: found only in milk. The hydrolysis of lactose in the intestine proceeds slowly, in connection with which the fermentation processes in the intestine are limited and the vital activity of beneficial intestinal microflora is normalized. The intake of lactose contributes to the development of lactic acid bacteria, which suppress the development of putrefactive microorganisms in the intestine. Source - milk and dairy products. The content of lactose in milk is 4-6%.

COMPLEX CARBOHYDRATES.

Starch: The high starch content is largely due to the nutritional value grain products, legumes, potatoes. Starch has only colloidal solubility. It contains 2 fractions of polysaccharides - amylose and aminolectin. Amylose in starch 15-25%, amylopectin - 75-85%. Under the influence of enzymes and acids, starch undergoes hydrolysis with the formation of dextrins. The final transformation of dextrins is the formation of maltose, which, under the influence of enzymes, turns into glucose, and it is used for the needs of the body.

Glycogen - is found in a significant amount in the liver. It is used in the body to nourish working muscles, organs and systems as an energy material.

Pectin substances: according to their chemical structure, they can be classified as hemicelluloses - colloidal polysaccharides or glucopolysaccharides. There are two main types:

Propectins are water-insoluble native plant pectins. They are contained in the cell walls of fruits, forming an intercellular layer in their tissues and being a binding and fastening material between individual cells.

· Pectins - are soluble substances that are absorbed in the body. The main property of pectin substances is the ability to transform in an aqueous solution in the presence of acids and sugar into a jelly-like colloidal mass. With the fiber of fruits and berries, pectin substances form a useful biological complex that improves digestion. Under the influence of pectin substances, the intestinal microflora changes, towards its normalization, putrefactive processes decrease, intestinal motility improves.

The detoxifying properties of pectin in case of lead poisoning have been noted. In this regard, the inclusion of lead in the diet of workers may have a preventive value.

The therapeutic effect of pectins in the treatment of diarrhea of ​​various etiologies in adults and children has long been known.

Some researchers explain these properties by the high adsorption capacity of pectin, others by its environment, as well as by the formation of metal ions during splitting in the digestive tract, which are part of pectin and have high catalytic activity. In addition, the ability of pectin to bind a number of substances in our body, including radioactive ones - strontium and cobalt, has been established.

The source of the pectin-fiber complex is fruits, berries, and some root crops. They are rich in oranges, cherries, apples, plums, gooseberries, black currants. A lot of pectin contains radishes, beets, carrots.

Food pectin is obtained from the waste of apples, as well as from sunflowers. Pectin preparations have become widespread. specially designed for therapeutic purposes (Swiss drug "Diarex").

Cellulose (fiber) - in the human intestine, the glandular apparatus does not produce enzymes that break down cellulose and, thus, is not able to digest it. However, some intestinal bacteria produce enzymes that break down cellulose. The lower the fiber, the more completely it breaks down. Grains are high in fiber. Less coarse, delicate fiber is well broken down in the intestines and is better absorbed (potato fiber, vegetables). Fiber stimulates intestinal motility, helping to eliminate cholesterol from the body, and normalizes beneficial intestinal microflora.

The need for carbohydrates is determined by the amount of energy consumption. The average need for carbohydrates of persons not engaged in heavy physical labor is determined in the amount of 400-500 g / day, including starch 350-400 g, monosaccharides - 50-100 g, dietary fiber (fiber, pectin) - 25 g. Rationing carbohydrates can be produced according to the energy value of the daily diet. For every megacalorie, there are 137 grams of carbohydrates.

BALANCED NUTRITION.

A balanced diet provides for the optimal ratio for the human body in the daily diet of proteins, amino acids, fats, fatty acids, carbohydrates, vitamins.

According to the formula of a balanced diet (Pokrovsky A.A., 1977), the ratio of proteins, fats and carbohydrates should be on average 1:1:4 (Table 5). In the current recommendations, the ratio is 1:1.2:4.6. The amount of proteins in the diet is 11-13% of the daily energy value, fats - an average of 33% (for the southern regions - 27-28%, for the northern - 38-48%), carbohydrates - about 55%. The balance of animal proteins is 60% of the total protein. The balance of essential amino acids, especially tryptophan, methionine and lysine, is important. The largest amount of lysine is found in meat, fish, cottage cheese, eggs; methionine - in cottage cheese, chicken meat, peas, beans, soybeans, grain products.

In order for the body to be provided with polyunsaturated fatty acids, about 30% of fats must be supplied to it in the form of vegetable oils. Thus, 10% of the total fat in the diet should be polyunsaturated fatty acids, found mainly in plant foods; 30% are saturated fatty acids and 60% are monounsaturated acids.

Of the total amount of carbohydrates, 745% is allocated to polysaccharides, in particular starch, 20% to mono- and disaccharides, 3% to pectins and 2% to dietary fiber.

The need for a balance of vitamins is determined by the body's need for energy. So for the amount of food having energy value 4187 kJ (1000 kcal), ascorbic acid (vitamin C) is required - 25 mg; thiamine (vitamin B 1) - 0.6 mg; riboflavin (vitamin B 2) - 0.7 mg; niacin (vitamin PP) - 6.7 mg; pyridoxine (vitamin B 6) - 0.7 mg; etc. Vitamin provision of the body is achieved through the intake of these substances with food products of both plant and animal origin.

The optimal ratios of calcium (Ca), phosphorus (P) and magnesium (Mg) for the body have been established. In a balanced diet of an adult, the ratio of Ca: P = 1:1.5; Ca: Mg= 1: 0.5.

DIET