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Food substances and their value.

The human body consists of proteins (19.6%), fats (14.7%), carbohydrates (1%), mineral substances (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 the implementation of all life processes, including physical and mental work.

1. Belki

These are complex organic compounds from amino acids, which include carbon (50-55%), hydrogen (6-7%), oxygen (19-24%), nitrogen (15-19%), and also 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 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 a person’s life (digestion, growth, reproduction, immunity, etc.), promote normal metabolism of vitamins and mineral salts in the body. Proteins are involved in the formation of energy, especially in a period of high energy costs or with insufficient amounts of carbohydrates and fats in the diet, covering 12% of the entire body's need for energy. The energy value of 1 g of protein is 4 kcal.

With a lack of proteins in the body, serious disorders occur: slowing the growth and development of children, changes in the liver of adults, the activity of the endocrine glands, blood composition, weakening of mental activity, reduced efficiency and resistance to infectious diseases.

Amino acids according to biological value are divided into irreplaceable and replaceable ones.

Essential amino acids eight - lysine, tryptophan, methionine, leucine, isoleucine, valine, threonine, phenylalanine; children also need histidine. These amino acids in the body are not synthesized and must necessarily come from food in a certain ratio, i.e. balanced. Especially valuable are the essential amino acids tryptophan, lysine, methionine, which are mainly contained in animal products, whose ratio in the diet should be 1: 3: 3.

Replaceable amino acids (arginine, cystine, tyrosine, alanine, series, etc.) can be synthesized in the human body from other amino acids.

A protein containing all eight essential amino acids is called complete. The source of high-grade proteins are all animal products: dairy, meat, poultry, fish, eggs.

Herbal products contain less protein and they are mostly inferior, except legumes (especially soy), which contain many high-grade proteins.

The daily rate of protein intake for people of working age is only 58-117 grams, depending on gender, age, and the nature of human labor. Proteins of animal origin should be 55% of the daily requirement. In addition, in the preparation of the diet should take into account the balance of amino acid composition of food. The most favorable amino acid composition is presented in combination of such products as bread and cereal with milk, meat pies, dumplings.

2. Fat

These are complex organic compounds consisting of glycerol and fatty acids, which contain carbon, hydrogen, oxygen. Fats are classified as basic food substances, they are an essential component in a balanced diet.

Fat is part of the cells and tissues as a plastic material, used by the body as an energy source (30% of the body’s total energy requirements). 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 the food juiciness, taste, increase its nutritional value, causing a person to have a feeling of fullness.

The balance of incoming fat after covering the needs of the body is deposited in the subcutaneous tissue as a subcutaneous fat layer and in the connective tissue surrounding the internal organs. Both subcutaneous and internal fat are the main reserve of energy (reserve fat) and is used by the body during enhanced 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 intake, there are a number of disorders on the part of the central nervous system, the body's defenses weaken, protein synthesis decreases, capillary permeability increases, growth slows down, etc.

Fatty acids are divided into limiting or saturated (i.e., to the limit saturated with hydrogen) 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, contribute to the development of atherosclerosis, as they increase blood cholesterol.

Unsaturated fatty acids (oleic, linoleic, linoleic, arachidonic, etc.) are biologically active compounds capable of oxidizing and attaching hydrogen and other substances. The most active of them: linoleic, linolenic and arachidonic, called polyunsaturated fatty acids. According to their biological properties, they are referred to as vital substances and are called vitamin F.

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

Phosphatides are the most biologically active substances. These include lecithin, kefalin and others. They affect the permeability of cell membranes, the metabolism, the secretion of hormones, blood clotting. Phosphatides are found in meat, egg yolk, liver, food fats, sour cream.

Sterols are an integral part of fats. In vegetable fats, they are presented in the form of beta-sterol, ergosterol, affecting the prevention of atherosclerosis.

In animal fats, sterols are contained in the form of cholesterol, which ensures the normal state of the cells, participates in the formation of germ cells, bile acids, vitamin D3, etc.

Cholesterol, in addition, is formed in the human body. Under normal cholesterol metabolism, the amount of cholesterol that comes from food and is synthesized in the body is equal to the amount of cholesterol that breaks down and is removed from the body.

3. Carbohydrates

These are organic compounds consisting of carbon, hydrogen and oxygen, synthesized in plants from carbon dioxide and water under the action of solar energy.

Carbohydrates, having the ability to oxidize, are the main source of energy used in the process of human muscle activity. The energy value of 1 g of carbohydrates is 4 kcal. They cover 58% of the entire body's need for energy. In addition, carbohydrates are part of the cells and tissues contained in the blood and in the form of glycogen (animal starch) in the liver. There are few carbohydrates in the body (up to 1% of human body weight). Therefore, to cover energy costs, they must come with food constantly.

In the case of a lack of carbohydrate in the diet during heavy physical exertion, energy is generated from the stored fat, and then the body's protein. With an excess of carbohydrates in the diet, the fat reserve is replenished due to the conversion of carbohydrates into fat, which leads to an increase in human weight.

The source of the body's supply of carbohydrates are plant products, in which they are presented as monosaccharides, disaccharides and polysaccharides.

Monosaccharides are the simplest carbohydrates, sweet in taste, soluble in water. These include glucose, fructose and galactose.

Glucose is found in many fruits and berries (grapes) and is formed in the body during the breakdown of disaccharides and food starch.

Fructose, having the same properties as glucose, is more beneficial for the human body. It is three times sweeter than glucose and twice the sucrose, which allows, without reducing the level of sweetness of food, to use less Contained fructose in honey, apples, pears, watermelon, currants, etc.

Galactose in its free form is not found in food products, it is an integral part of milk sugar (lactose), it has a weak sweet taste. Like fructose, favorable for the body, does not increase the sugar content in the blood.

Disaccharides (sucrose, lactose and maltose) are carbohydrates, sweet in taste, soluble in water, are split in the human body into two monosaccharide molecules to form glucose and fructose from sucrose, lactose from glucose and galactose, and maltose from two glucose molecules .

Sugar (beet sugar) a person consumes mainly in the form of sugar, in which its 99.9%, in addition, it is contained in beets, carrots, plums, apricots, bananas.

Lactose (milk sugar) enters the body with milk and dairy products, has a beneficial effect on the vital activity of lactic acid bacteria in the intestine, thereby suppressing the development of putrefactive microbes.

Maltose (malt sugar) is not found in natural foods.
In the human body during digestion, maltose is formed as an intermediate in the hydrolysis of starch to glucose.

Polysaccharides are complex carbohydrates, consisting of many glucose molecules, insoluble in water, have a savory taste. These include starch, glycogen, fiber.

Starch in the human body under the action of the enzymes of the digestive juices splits to glucose, gradually satisfying the body's need for energy for a long period.

Glycogen enters the human body in small doses, as it is contained in small amounts in food of animal origin (liver, meat). In the process of digestion, food glycogen is broken down to glucose. In humans, glycogen is formed from glucose and accumulates in the liver as a reserve energy material.

Cellulose in the human body is not digested due to the absence of the enzyme cellulase in the digestive juices, but passing through the digestive organs stimulates intestinal motility, removes cholesterol from the body, creates conditions for the development of beneficial bacteria, thereby contributing to the best digestion and assimilation of food.

Inulin in the human body during digestion is broken down to fructose, which does not increase the sugar content in the blood and quickly turns into glycogen. Inulin is contained in the Jerusalem artichoke, in the chicory root, which is recommended for patients with diabetes.

Pectin (carbohydrate-like) substances, entering the human body with vegetables, fruits, stimulate the digestive process and promote the removal of harmful substances from the body. Pectic substances are abundant in apples, plums, gooseberries, cranberries.

The daily rate of consumption of carbohydrates for the working-age population is only 257–586 g, depending on age, sex, and the nature of labor. Easily digestible carbohydrates for people of mental labor and the elderly should be 15%, and for people of physical labor 20% of the daily carbohydrate norm; 75% of this norm is polysaccharide, mainly in the form of starch; 5% pectin and fiber.

4. Vitamins

These are low-molecular organic substances of various chemical nature, playing the role of biological regulators of life processes in the human body.

Vitamins are involved in the normalization of metabolism, in the formation of enzymes, hormones, stimulate growth, development, and recovery of the body.

They are of great importance in the formation of bone tissue (Vit. D), skin (Vit. A), connective tissue (Vit. C), in the development of the fetus (Vit E), in the process of blood formation (Vit. B12, Vd) and t .d

Some vitamins in the body are not synthesized and are not deposited in the stock, so they must be introduced with food (C, B, P). Some vitamins can be synthesized in the body (B2, B6, B9, PP, K).

Lack of vitamins in the diet causes the disease under the general name avitaminosis. With inadequate intake of vitamins with food, hypovitaminosis occurs, which manifests itself in the form of irritability, insomnia, weakness, decreased working ability and resistance to infectious diseases. Excessive intake of vitamins A and D leads to poisoning of the body, called hypervitaminosis.

Depending on solubility, all vitamins are divided into: 1) water-soluble C, P, B, B2, B6, Bd, PP, etc .; 2) fat-soluble - A, D, E, K; 3) vitamin-like substances - U, F, B4 (choline), B, 5 (pangamic acid), etc.

Vitamin C (ascorbic acid) plays a large role in the redox processes of the body, affects the metabolism. The lack of this vitamin reduces the body's resistance to various diseases. Lack of it leads to scurvy. The daily intake of vitamin C 70-100 mg. It is found in all vegetable products, especially its many in wild rose, black currant, red pepper, parsley, dill.

Vitamin P (bioflavonoid) strengthens the capillaries and reduces the permeability of blood vessels. It is contained in the same products as vitamin C. The daily intake of 35-50 mg.

5. Mineral substances

Mineral, or inorganic, substances are among the indispensable, they are involved in vital processes in the human body: building bones, maintaining acid-base balance, blood composition, normalization of water-salt metabolism, the activity of the nervous system.

Depending on the content in the body, minerals are divided into:

Macronutrients that are in significant amounts (99% of the total minerals contained in the body): calcium, phosphorus, magnesium, iron, potassium, sodium, chlorine, sulfur.

Trace elements that are part of the human body in small doses: iodine, fluorine, copper, cobalt, manganese;

Ultramicroelements contained in insignificant quantities in the body: gold, mercury, radium, etc.

Calcium is involved in the construction of bones, teeth, is necessary for the normal activity of the nervous system, heart, affects growth. Calcium salts are rich in dairy products, eggs, cabbage, beets.

Phosphorus is involved in the metabolism of proteins and fats, in the formation of bone tissue, affects the central nervous system. Contained in dairy products, eggs, meat, fish, bread, legumes.

Magnesium affects the nervous, muscular and cardiac activities, has vasodilating properties. Contained in bread, cereals, legumes, nuts, cocoa powder.

Iron normalizes the composition of blood (entering hemoglobin) and is an active participant in the oxidative processes in the body. Contained in liver, kidneys, eggs, oats and buckwheat, rye bread, apples. Daily need for iron 0,018 g

Potassium is involved in the water metabolism of the human body, enhancing fluid excretion and improving the work of the heart. Contained in dry fruits (dried apricots, dried apricots, prunes, raisins), peas, beans, potatoes, meat, fish.

Sodium together with potassium regulates water metabolism, retaining moisture in the body, maintains normal osmotic pressure in the tissues. Sodium in food is low, so it is injected with table salt.

Chlorine is involved in the regulation of osmotic pressure in the tissues and in the formation of hydrochloric acid (HC1) in the stomach. Chlorine enters with table salt.

Sulfur is a component of some amino acids, vitamin B, the hormone insulin. Contained in peas, oatmeal, cheese, eggs, meat, fish.

Iodine is involved in the construction and operation of the thyroid gland. Most iodine is concentrated in sea water, sea kale and sea fish.

Fluoride is involved in the formation of the teeth and bone skeleton, is contained in drinking water.

Copper and cobalt are involved in blood formation. Contained in small quantities in food of animal and vegetable origin.

To maintain the acid-base balance in the body, it is necessary to properly combine in the diet foods containing alkaline minerals (Ca, Mg, K, Na), which are rich in milk, vegetables, fruits, potatoes, and acidic (P, S, C1) which are found in meat, fish, eggs, bread, cereals.

6. Water

Water plays an important role in the life of the human body. It is the most significant component of all cells (2/3 of the human body weight). Water is an environment in which cells exist and the connection between them is maintained, it is the basis of all fluids in the body (blood, lymph, digestive juices). With the participation of water, metabolism, thermoregulation and other biological processes occur.

Drinking water quality must meet the requirements of the current GOST Drinking Water.

Water metabolism in the body is regulated by the central nervous system and is closely associated with the mineral metabolism of potassium and sodium salts. With a large loss of water by the body with sweat or increased consumption of table salt, the osmotic pressure of blood plasma changes, which leads to arousal in the cerebral cortex, resulting in a feeling of true thirst, which regulates human consumption of water. False thirst due to dry mouth, unlike true, does not require the entry of water into the body. To remove this sensation, it is enough to increase the salivation with an acidic product or moisten the mouth with water.

Questions for self-control

1. The value of nutrients.

2. Proteins. Their role in the human body.

3. Fats. Their role in the human body.

4. Carbohydrates. Their role in the human body.

5. Vitamins. Their role in the human body.

6. Fat-soluble vitamins.

7. Water soluble vitamins.

8. Mineral substances. Their role in the human body.

9. Water. Its role in the human body.
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