Proteins are the most important necessary component of nutrition, since the life of the body cannot be imagined without them..

It is an integral part of cells and intercellular substance, with the help of proteins plastic and catalytic processes are carried out.

All enzymes have a protein structure.

The contractile function is carried out by proteins of muscle tissue - actin, myosin.

The protective function of blood immunoglobulin proteins is great. For the normal development of the body, not only the quantitative, but also the qualitative composition of the protein is important.. Protein constituents are amino acids, which are divided into nonessential and non-essential. About 22 amino acids are of great importance in nutrition, while about 60 amino acids are known to science.. Essential amino acids must necessarily enter the body with food.

These are methionine, lysine, tryptophan, phenylalanine, leucine, isoleucine, threonine, valine. In childhood, the amino acid histidine is also indispensable, since due to imperfect synthesis processes, it is not formed in the child's body in the proper amount.

Some essential amino acids are growth factors. These are, first of all, lysine, tryptophan, histidine. In meat, fish, eggs, these amino acids are in the required amount. Eggs are also very valuable as a source of vitellin protein. This protein, combining with lecithin of neuronal membranes, plays an important role in the formation of nerve tissue.

Thus, a child needs a high level of animal protein: at a young age (up to 6 years) - 65-70%, at school - 60% of the total protein consumed per day. At the age of one to three years, a child should receive 4 g of protein per 1 kg of body weight, at 8 years old the need decreases to 3 g, and children over 11 years old need about 2.5-2 g.

Everyone knows that milk protein meets the needs of the child's body.. Milk as a whole is a unique product. Also. Pavlov, characterizing milk as a priceless product, wrote: “The weakest gastric juice is poured into milk, as well as the smallest amount of pancreatic juice. The secretory work produced by the body to assimilate milk is much less than that with other food "

Milk components are perfectly balanced and easy to digest. Milk protein, unlike meat protein, does not contain nucleotides - a source of uric acid. In addition, milk contains a large number of amino acids such as tryptophan, lysine, methionine.. The main protein in milk is casein. It is this protein that is associated with milk calcium, forming an easily digestible complex.

Other lower amounts of milk proteins are lactalbumin and lactoglobulin. According to the biological effect, milk globulins have an antibiotic effect. Albumin is valuable for its high content of the amino acid tryptophan, which is a growth factor.

Milk fats are valuable for the presence of arachidonic acid. Carbohydrates are represented by a monosaccharide - lactose, which is not found anywhere else. Calcium found in milk is the most easily digestible. In addition, milk contains a whole complex of vitamins: A, B2, D, carotene, tocopherol, ascorbic acid. However, human milk differs from milk of farm animals in chemical composition.. Comparative composition of human and cow's milk is presented in table 27.

For infants, cow's milk as a substitute for female milk is not entirely suitable due to the peculiarities of children's digestion. The fact is that, having been born, the child is adapted to the ingredients of the mother's milk, since there is a commonality of the enzymatic systems of the mother and the fetus. But no matter how close artificial nutritional mixtures are in composition to human milk, they cannot completely replace it.. It is especially important to take this into account in the first months of a child's life..

Some of the causes of undernutrition in an infant are:.

1) the beginning of breastfeeding should be carried out no later than 30 minutes after childbirth;

2) there should be no feeding " Normally - about 8 times a day, including at night;

3) violation of the technique of attachment to the chest;

4) using a bottle to feed reduces the baby's need for sucking;

5) in the first four months, the child does not need feeding with glucose, juices.

According to I. Vorontsova, human milk satisfies the body's needs until the doubling of body weight. Then the child needs additional food. These are primarily minerals that a person receives from plant foods.. Therefore, complementary foods are primarily vegetables, fruits. The first type of complementary foods is 5% semolina porridge, cooked in vegetable broth in half with milk.

Dishes should be homogeneous in consistency so that it is not difficult for the child to swallow. On the first day before breastfeeding, give 3-5 teaspoons of porridge. Usually, during the first week, one feeding is completely replaced by complementary foods.. When a child gets used to 5% porridge, they gradually switch to 10% porridge, which is prepared in whole milk..

Then gradually, after about 2 weeks, they switch to the second type of complementary foods - vegetable puree. Thus, a child of 6 months receives breast 3 times and 2 times - semolina or rice porridge, vegetable puree. From 7 months, semolina porridge is alternated with buckwheat, which is rich in B vitamins.

Also, a 7-month-old baby is given meat broth, minced meat is added to the feeding. At 8 months, another breastfeeding is replaced with pureed cottage cheese. By the age of 9 months, the baby is given breast 2 times - in the morning and in the evening. These are the general rules for the introduction of complementary foods.. If you follow them, then the baby is weaned painlessly.. This usually occurs at the age of one.

Fats.

Fat is an essential nutritional component, an energetically valuable product. They account for about 30% of the daily energy composition of the diet.. Fat constituents - such as phosphatides, polyunsaturated fatty acids (PUFA), sterols - are of great physiological importance. Phospholipids (phosphatides) are biologically active molecules that make up cell membranes.

They take part in the transport of fat in the body.. A lot of phosphatides are found in nervous tissue, brain structures. They can be partially synthesized in the body. This process takes place in the liver, kidneys. The most common phosphatides are lecithin, sphingomyelin, cephalin. Lecithin plays a large role in cholesterol metabolism.

By preventing the accumulation of the latter, lecithin promotes its breakdown. The content of lecithin in the blood is an important diagnostic sign. Normal: 2.2-2.9 mmol / l. Lecithin / cholesterol ratio \u003d 0.9-1.4 (Myasnikov A. 1965 g). Main food source - eggs, butter.

Edible fats of animal origin in their composition contain zoosterols, vegetable fats - phytosterols. Among sterols, cholesterol is of greatest interest.. It participates in the synthesis of a number of hormones, vitamin D, in the conversion of bile acids. If cholesterol metabolism is impaired, then it acts as an atherogenic factor.

The next most important and irreplaceable component of dietary fats is polyunsaturated fatty acids. It is linoleic, linolenic, arachidonic acid. Some researchers consider them a complex vitamin F. The formation of myelin sheaths, connective tissue is associated with PUFA. They play a role in the metabolism of choline, B vitamins; favorably affect the vascular wall, increasing the elasticity of blood vessels.

Arachidonic acid is a precursor of some prostaglandins, which are of great importance. These are the so-called " With a lack of PUFA, growth processes are also disrupted, resistance to adverse environmental factors decreases, and skin lesions are observed.

Based on these many functions and properties, it is clear that children need more PUFAs than adults.. If the daily diet of an adult includes 1% PUFA, then the child's diet requires 2%. The main source is vegetable oils. Thus, a complete diet must necessarily include fats of both animal and vegetable origin..

A child under 6 years old should receive 6-12 g of vegetable fats, children of primary school age - 20 g and adolescents - 25 g. As for the number of calories in fat, their number at an early age is 40-50% and decreases to 30% in school. But, if the ratio of proteins and fats is disturbed, this negatively affects the health of the child.. The optimal ratio for children over 1 year old is 1: 1.

Carbohydrates.

Carbohydrates are the main source of energy for muscle activity in children.. The processes of glycolysis in the child's body are the most intense, so the need for carbohydrates is increased. Fruits, juices, berries are sources of easily digestible carbohydrates: glucose and fructose. As mentioned above, milk is an important product as it contains the monosaccharide lactose..

It is important that the slightest changes in blood sugar levels cause disruption in the course of various processes in the body..

Complex sugars are polysaccharides: glycogen, pectin substances. The latter have bactericidal, adsorptive properties. Glycogen, deposited in the organs, creates an energy reserve. You need to know that the daily caloric intake of carbohydrates for children is 50%. The optimal ratio of proteins, fats and carbohydrates in the diet of a child over 1 year old is 1: 1: 4 and for schoolchildren - 1: 1: 5.

Violation of this balance causes nitrogen retention in the body, i.e.. with a lack of carbohydrates, protein metabolism is disrupted. With an excess of carbohydrates, fat metabolism is disturbed, an intensive replenishment of fat depots takes place, which ultimately leads to obesity. Approximate norms of the needs of children and adolescents in nutrients and energy are shown in Table 28.

Vitamins.

Vitamins - life regulators. Required in small quantities, they nevertheless play a large role in the body.. The norms of the physiological need for vitamins (per day) of children and adolescents are shown in Table 29.

Distinguish between fat- and water-soluble vitamins. The latter are constituents of many enzymes, therefore, with a deficiency of water-soluble vitamins, the rate of catalytic reactions sharply decreases.

Fat-soluble vitamins (A, D, E, K) are also called hormone vitamins, i.e.. these are a kind of tissue hormones. Fat-soluble vitamins are necessarily part of the cell membranes, the structure and functions of which are in optimal conditions with a sufficient amount of vitamins. The health of children is most influenced by vitamins that affect growth processes. These are, first of all, vitamins of groups A, D.

Vitamin A - retinol. The function of the endocrine glands, in particular the pituitary gland, the growth process of skeletal tissue directly depends on its amount.. The effect of retinol on vision processes is also enormous: with its lack, daytime vision and color perception are impaired, and a specific visual impairment occurs - "

This vitamin is found in animal products: meat, fish, butter, and the precursor of retinol, carotene, is found in all plant foods of red-orange color..

Vitamins of group D - calciferols - regulators of calcium and phosphorus metabolism in the body, are of extreme importance in childhood. A dangerous consequence of a lack of this vitamin at a young age is rickets. Vitamin comes not only with food, but is also synthesized endogenously, due to the action of UV rays, therefore walks in the fresh air are very useful and important, because. using a natural source of ultraviolet radiation - the Sun.

Vitamin source - fish oil. It is a very important and valuable product.! In addition to its high content of fat-soluble vitamins, it is also rich in arachidonic acid. Vitamin preparations are prepared on the basis of fish liver oil. In addition to fish products, there is a lot of vitamin D in meat, beef liver, eggs, dairy products.

Vitamin E - tocopherol plays an important role in baby food. Firstly, it affects the absorption and proper use of vitamins A and D, and secondly, it activates the transition of carotene to retinol, i.e.. is an indirect growth factor.

Filoquinone - vitamin K - affects blood coagulation processes. The only fat-soluble vitamin that is a coenzyme, i.e.. participates in the catalytic reaction of the transition of prothrombin to thrombin. In an adult, it is normally synthesized by the intestinal microflora, and in a child, as a result of incomplete development of microflora, this process is not carried out.

Of the water-soluble vitamins, B vitamins and ascorbic acid - vitamin C play the greatest physiological role..

B1 - thiamine - takes part in all cellular oxidation processes, especially important in the metabolism of carbohydrates. If a child eats a lot of sweets, and does not receive enough vitamin B1, then the body does not completely burn carbohydrates and the products of their intermediate metabolism accumulate: pyruvic and lactic acids.

B2 - riboflavin - takes part in protein metabolism, normalizes vision, has a positive effect on growth.

B6 - pyridoxine is involved in the exchange of amino acids: tryptophan and glutamic acid. If this exchange is disturbed, changes occur in the central nervous system..

Vitamin C - ascorbic acid - significantly affects the body's resistance to infectious agents. Vitamin takes part in all types of metabolism, directly or indirectly, and therefore is required in large quantities. As a prevention of C-vitamin deficiency is C-vitaminization of food.

It is held all year round in children's institutions: boarding schools, kindergartens, schools, hospitals, sanatoriums.

If any vitamin does not come from food or is not absorbed by the body, hypo- and avitaminosis occurs.

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