What nutrients are needed for the human body. Nutrients and their importance to the body

The daily diet of every person should consist of essential nutrients, which many people know almost nothing about. Although everyone should know about them, they are the ones that saturate our body.

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Proteins are complex organic compounds that contain amino acids. There are more than 80 of them and only 22 of them are distributed in food products. Proteins are necessary to perform many functions of the human body - they are involved in the processes of building tissues, cells, organs, in the formation of enzymes, hemoglobin, many hormones and other compounds. They also take part in the formation of compounds, and help to ensure the body's immunity to various infections.

Without proteins, the processes of assimilation of carbohydrates, fats, vitamins and minerals. Proteins do not have the ability to accumulate and form from other substances, which fundamentally distinguishes them from carbohydrates and fats.

Proteins for the human body are simply an indispensable part of nutrition. Due to an insufficient amount of protein in the body, quite serious disturbances in the composition of the blood can occur, in mental activity, work of glands internal secretion may also slow growth and development small child and, accordingly, resistance to various viruses and infections will decrease. When it comes to energy sources, proteins are not the main substance, since they can be replaced by both carbohydrates and fats. The formation of proteins in the human body comes from the amino acids that come with the food taken.

Amino acids are divided into two main groups:

• Essential amino acids (phenylalanine, valine, leucine, lysine, threonine, isoleucine, methionine, tryptophan). These amino acids are not synthesized in the human body, so the body can only get them with food, which is very necessary. These amino acids are rich in animal products.

• Essential amino acids (alanine, cystine, arginine, tyrosine and others). These amino acids can be synthesized from other amino acids found in the human body.

By amino acid composition it is possible to distinguish defective and complete (indispensable amino acids) proteins. The source of complete proteins are following products- milk, poultry, fish, meat, eggs. Food plant origin not rich complete proteins. When compiling a diet, it is worth knowing that more than 90% of amino acids are absorbed in the body from animal products, about 60-80% from vegetable proteins.

Fats

Fats are complex organic compounds that are made up of fatty acids and glycerin. In human nutrition, in addition to neutral (own) fats, fatty substances(sterol, phospholipid). Fats occupy the most important place in the body's energy supply. Fat accounts for approximately 30% of energy needs. Fats are included in the composition cell structures as well as the cells themselves. They are involved in the metabolic process. Together with fats, the human body also receives the substances necessary for it, such as lecithin, fatty acids and vitamins A, D, E.

A large amount in the human body adversely affects the absorption of calcium, proteins, magnesium, and also increases the body's need for vitamins, which help to ensure fat metabolism. Excessive consumption of fats causes inhibition of the secretion of the stomach and the removal of food from it, and also exerts an overstrain of all functions of the organs of nutrition. As a result of all this, disorders in digestion, pancreas, gallbladder as well as the liver. When planning a diet, it is worth consuming fats as little as possible, especially with a small biological value.

Carbohydrates

Carbohydrates are organic compounds that include oxygen, hydrogen and carbon. Carbons are synthesized under the influence of sunlight in plants from carbon dioxide and water. Complex (polysaccharides - starch, fiber, klikogen, hemicellulose, pectin), simple (fructose, galactose, glucose, lactose, sucrose, maltose), digestible and indigestible carbohydrates enter the human body with food.

Carbohydrates are needed human body for the normal metabolism of fats and proteins. Together with proteins, they are involved in the formation of enzymes, hormones, salivary secretions. Separate importance should be noted in pectin, fiber, which play a major role in nutrition, forming the basis of dietary fiber. Glucose is the main source of energy for the brain. Berries and fruits are rich in glucose.

With insufficient content of carbohydrates in the body, there may be a violation of the metabolism of proteins and fats, as well as the consumption of tissue proteins and food proteins. With a lack of carbohydrates, a person will feel drowsiness, weakness, headaches, dizziness, nausea, trembling, hunger. Simple sugar will help get rid of these symptoms. When limiting the body in carbohydrates, for example, during a diet, you should pay attention to the fact that the amount consumed should not be less than 100 grams. Also, excess carbohydrate content has a negative effect. For example, an excess of carbohydrates can lead to obesity.

Vitamins and minerals

In addition to proteins, fats and carbohydrates, there are other nutrients in the human body, such as vitamins, trace elements and minerals. All these substances are simply necessary for a person to ensure that his body performs all processes. It is they who determine the usefulness of the food consumed. After all, the main component of the quality of all food products is the content of nutrients in it.

Vitamins in foods are contained in small quantities, but still necessary for a person to ensure his work. desired functions. It is they who help the body absorb other nutrients, and also participate in other important formations and formations. Only properly selected and cooked food can enrich the body with the vitamins it needs.

Minerals also play an important role in the functioning of the body. The main role of minerals is given in the formation of skeletal muscles, oxygen transport, regulation of heart contractions, transmission of nerve impulses, and so on. Along with calcium and phosphorus, minerals help form the bones of the human skeleton.

Antioxidants are the body's natural defense against harmful effects free radicals. To strengthen this protection, a person needs to enrich his diet with vegetables and fruits.

The lack of nutrients in the human body will not only affect its internal state, but it will also be visible from the outside. For example, a lack of vitamins and minerals will immediately affect the human skin. The lack of each substance will manifest itself in its own way, but negative effect will be noticeable, even if not immediately, then after a while it will appear and let you know about yourself. That is why nutritionists and doctors constantly talk about balanced diet, about the correctness of food, healthy diet and other things that can affect the human body and its proper functioning.

The need of the human body for these substances largely depends on the age and gender of the person, his physical activity and daily load. During stress or illness, a person needs much more substances than when his body is calm and healthy. Also, do not forget that children, pregnant women, the elderly also need more substances. It is a pity, but the substances in the body do not accumulate. Nutrients in products constitute their value. All products are characterized and divided depending on the content of the considered nutrients in their composition. Human nutrition should be varied and balanced. The diet should include all these substances for the full functioning of the body, as well as its proper functioning.

Nutrients- These are substances that are a source of energy and building material for the body. These include proteins, fats and carbohydrates.

Proteins are organic high-molecular compounds that are the main material for the implementation of the "building function in the body. Food proteins are broken down into amino acids in the alimentary canal. Of the 20 amino acids that make up proteins, the body can synthesize only half - non-essential amino acids, and the rest must be ingested with food - essential amino acids. Proteins that contain all the essential amino acids are called full-fledged(animal proteins), and those that lack at least one essential amino acid - defective (vegetable proteins). daily requirement organism in proteins - 118-120 g. In cells, proteins perform following features: building, catalytic, protective, regulatory, propulsion, transport, energy and others. With an excess of proteins are converted into fats and carbohydrates.

Fats are organic compounds that are insoluble in water due to their non-polarity and are an important source of energy for the body. Food fats in the alimentary canal are broken down into higher fatty acids and glycerol. The daily need for fats is 100-110 g. Fats can be synthesized in the body from carbohydrates and proteins, and their excess is deposited in the form brown fat or converted to carbohydrates. In cells, fats perform the following functions: energy, water-replenishing, storage, heat-regulatory and etc.

Carbohydrates are organic compounds that are the main source of energy for the body. Food carbohydrates are broken down into glucose in the alimentary canal. The daily requirement is 350-440 g. With a lack of carbohydrates in food, they can be formed from fats and partly from proteins, and with an excess they turn into fats. In cells, carbohydrates perform storage, energy and other functions.

The lack of certain organic compounds in our food is compensated to some extent by excessively others. But the lack of protein in food cannot be replenished, because they are built only from amino acids. Protein starvation is especially dangerous for the body. Interconversion of nutrients is shown in the diagram.

The centers of regulation of protein, fat, carbohydrate and water-salt metabolism are located in intermediate department brain and closely related to centers of hunger and gratification V hypothalamus. The influence on the metabolism in tissues is transmitted by the hypothalamic centers along the sympathetic and parasympathetic nerves, as well as through the endocrine glands, regulating the release of hormones by them. Biggest Influence carry out:

■ for protein metabolism - growth hormone(pituitary), thyroxine (thyroid)

■ for fat metabolism - thyroxine And sex hormones)

■ for the exchange of carbohydrates - insulin and glucagon(pancreas), glycocorticoids(adrenals)

■ on water-salt exchange - mineralocorticoids(adrenals) and antidiuretic hormone (ADG) (hypophysis).

Also in the hypothalamus thirst center, whose neurons fire in normal conditions an increase in the osmotic pressure of the blood that washes. In this case, there is a feeling of thirst and a behavioral reaction aimed at satisfying it. At the same time, through the secretion of ADH by the pituitary gland, the excretion of water from the body by the kidneys is inhibited, and with an excess of water in the body osmotic pressure blood flow decreases, and the hypothalamus gives the command to increase the excretion of water and reduce the excretion of salts.

It is no secret that food nutrients are used by the body, moreover, we need to constantly replenish them. But what role do they play, and in which products are they contained?

In total, there are six types of nutrients that the human body uses: water, minerals, vitamins, proteins, fats, carbohydrates. These are the main beneficial substances obtained from food, which are used to maintain the viability of tissues, renew them, generate energy for physiological activity and regulate metabolism. The need for them is experienced throughout life, and each substance performs certain functions.

Mechanism of absorption of nutrients by the body

Absorption of nutrients occurs only after their breakdown, in pure form they are not absorbed. Cleaved enzymes seep through the walls of the digestive tract, entering the bloodstream. Proteins, fats and carbohydrates provide the body with fuel in the form of calories. Water, minerals, vitamins perform the functions of a building and consumable material, which is no less important.

Water

This universal solvent is involved in almost all vital processes of the body:

• water nourishes the cells, preventing them from dehydration;
• transports substances and hormones to all organs;
• water helps burn fat by converting these cells into energy; its use in sufficient quantities reduces appetite;
• activates the work of the kidneys;
• digestion and excretion of waste products of the body are carried out in a liquid medium.

Lack of water inevitably leads to dysfunction internal organs, increase in adipose tissue. Brain cells are the first to experience water deficiency.

Minerals

Minerals can be divided into two groups: macro- and microelements. A sufficient amount of them in the body is responsible for the strength of the musculoskeletal system, water and acid-base balance, promotes the combination of proteins with lipids, strengthens the nervous system, etc. Trace elements, as a rule, for normal life needed in small amounts and macronutrients in large amounts. The lack of any mineral in the body inhibits the activity of other minerals.

Use of vitamins

Cellular nutrients such as vitamins play a very important role for human health, because their lack leads to a violation metabolic processes in the body and reduce immunity. This aspect is so important that people leading an active lifestyle are advised to take additional vitamin complexes. There are no vitamins in their pure form in nature: each of them exists in a complex biological complex, which, in fact, helps the body to use them.

Use of proteins

Protein is essential for tissue growth and repair. In addition, nutrients are used by the body in the production of hormones, enzymes and antibodies and the normal conduct of chemical reactions.

We consume proteins from meat, poultry, fish, cereals and legumes, milk, nuts and eggs. They contain amino acids, restore the expended energy and provide plastic processes in tissues. Increased amount protein food is recommended for children and pregnant women.

How fats are used by the body

The main nutrients, fats, are used by the human body to maximize the absorption of vitamins, energy production and protection against. There are three types of monounsaturated and polyunsaturated.

Dairy products, red meat, Coconut oil and some other products contain a large number of saturated fats; peanuts and olives are rich in monounsaturated fats; soy and vegetable oils(sesame, corn, etc.) are champions in polyunsaturated fats.

The supply of nutrients in this category provides cell plasticity, restores the compounds necessary for energy production and renewal of the body as a whole.

The role of carbohydrates in the life support of the body

(monosaccharides and polysaccharides, respectively) - in large quantities found in vegetables, fruits, whole grains, nuts, etc. These nutrients are used by the body primarily to produce vital energy. They participate in the synthesis of cells, are in close connection with fats, which allows them to interchange one with another. Starch is a powerful source of carbohydrate.

Useful for the intestinal microflora, indigestible fiber plays the role of a “panicle” that cleans it from toxins and toxins. It is a coarse vegetable fibers, which are complex carbohydrates. Food, rich in fiber improves the function of the gastrointestinal tract and of cardio-vascular system, increases resistance to various diseases.

Nutrient functions used by the body

All nutrients are used by the body in a specific way, although the main functions can be divided into three types.

1. Construction function, restoring the structure of cells and tissues. Useful substances are involved in the regeneration of internal and external organs. These are mainly proteins and some minerals, such as calcium, potassium, phosphorus, etc.;
2. Energy function: Nutrients such as fats and carbohydrates, and secondarily proteins, are used by the body to provide energy for metabolism. They help maintain a certain body temperature, perform muscle movements, etc .;
3. The control function for which various vitamins and minerals. With their help, the chemical reactions of metabolism and the activity of the internal organs are regulated.

For healthy eating it is important to observe the ratio of all nutrients and not to forget about the correct combination of various products.

Food groups and energy value

Nutrients in foods are contained in different quantities, which is why the food in the diet should be varied.

So, fruits are rich in sugars, vitamins and water; sweet desserts are quickly digested and moderate consumption serve as a good source of energy. Vegetables should be eaten regularly, because with a minimum energy component they have a fairly high content of vitamins and minerals responsible for metabolism.

Root vegetables and cereals are used by the body as a powerful source of energy, with a large amount of complex carbohydrates.

Meat, fish and eggs are a storehouse of "building material" of protein cells, and milk and dairy products contain a lot of fats, proteins, as well as calcium and other valuable trace elements.

In counting energy value food products, the unit of heat transfer is used - kilocalorie (kcal), which corresponds to the temperature of 1 liter of distilled water spent to raise the temperature from 14.5 ° C to 15 ° C. Almost all the necessary nutrients are involved in the production of thermal energy for the biochemical reactions of metabolism, the implementation of the motor function of muscles and the maintenance normal temperature body. It is the processing of fats and carbohydrates that releases a certain amount of energy.

Nutrients during digestion

Animal and plant food has all necessary for the body types of elements. But by themselves, meat, milk, or, for example, bread, are not absorbed by cells. Only pre-treatment guarantees absorption useful substances. Proteins, fats and carbohydrates are broken down into simpler particles of which they are composed and which are then used in metabolic processes.

Proteins are made up of amino acids, to which they are broken down in digestive tract. Fats are a complex combination of fatty acids with glycerol in a ratio of 3:1 in one molecule. The acids are different, so fats of different composition are obtained from them.

Fiber, starch and others complex carbohydrates consist of monosaccharides, the most famous representative of which is glucose. These substances look like a chain of 6 carbon atoms, with oxygen and hydrogen atoms attached “on the side” according to the scheme: 2 hydrogen and 1 oxygen per 1 carbon atom. As if the water molecule H₂O stuck to it, hence the name of this group of compounds - carbohydrates.

Thus, if water, vitamins and minerals can be used by the body in their usual form, as found in foods, then proteins during digestion are first broken down into amino acids, fats into glycerol and fatty acids, and carbohydrates into monosaccharides.

The cycle of digestion consists of mechanical (chopping, mixing, etc.) and chemical processing of food (splitting into simpler components). These processes are carried out under the action of enzymes of digestive juices. Thus, work is carried out in these bodies muscle tissue and endocrine glands, which require all the same nutrients that we talked about to function.

Human food contains the main nutrients: proteins, fats, carbohydrates; vitamins, microelements, macronutrients. Since our whole life is a metabolism in nature, for a normal existence, an adult must eat three times a day, replenishing his "reserve" of nutrients.

In the body of a living person, the processes of oxidation (combination with oxygen) of various nutrients are continuously going on. Oxidation reactions are accompanied by the formation and release of heat necessary to maintain the vital processes of the body. Thermal energy ensures the activity muscular system. Therefore, the harder the physical labor, the more food the body requires.

The energy value of food is usually expressed in calories. A calorie is the amount of heat required to heat 1 liter of water at 15°C by one degree. The calorie content of food is the amount of energy that is formed in the body as a result of the assimilation of food.

1 gram of protein, when oxidized in the body, releases an amount of heat equal to 4 kcal; 1 gram of carbohydrates = 4 kcal; 1 gram of fat = 9 kcal.

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Proteins support the basic manifestations of life: metabolism, muscle contraction, nerve irritability, the ability to grow, expand, and think. Proteins are found in all tissues and body fluids, being their main part. Proteins are made up of a variety of amino acids that biological significance one protein or another.

Non-essential amino acids are formed in the human body. Essential amino acids enter the human body only with food. Therefore, for the physiologically complete life of the body, the presence of all essential amino acids in food is necessary. A dietary deficiency of even one essential amino acid leads to a decrease in the biological value of proteins and can cause protein deficiency, despite a sufficient amount of protein in the diet. The main supplier of essential amino acids: meat, milk, fish, eggs, cottage cheese.

The human body also needs plant proteins, which are found in bread, cereals, vegetables - they include non-essential amino acids. Products containing animal and vegetable proteins provide the body with substances that are necessary for its development and vital activity.

The body of an adult should receive approximately 1 gram of protein per 1 kg of total weight. It follows that the "average" adult weighing 70 kg should receive at least 70 g of protein per day (55% of the protein should be of animal origin). With severe physical activity increasing protein requirements.

Proteins in the diet cannot be replaced by any other substances.

Fats

Fats surpass the energy of all other substances, participate in recovery processes, being a structural part of cells and their membrane systems, serve as solvents for vitamins A, E, D, and contribute to their absorption. Also, fats contribute to the development of immunity and help the body to keep warm.

Lack of fat leads to disruption of the activity of the central nervous system, changes in the skin, kidneys, organs of vision.

The composition of fats contains polyunsaturated fatty acids, lecithin, vitamins A, E. The average need for an adult in fat is 80-100 g per day, including vegetable fat - 25..30 g.

Due to fat in food, a third of the daily energy value of the diet is provided; There are 37 g of fat per 1000 kcal.

Fats are found in sufficient quantities in the brain, heart, eggs, liver, butter, cheese, meat, lard, poultry, fish, milk. Especially valuable vegetable fats containing no cholesterol.

Carbohydrates

Carbohydrates are the main source of energy. Carbohydrates account for 50-70% of the daily caloric intake. The need for carbohydrates depends on the energy consumption of the body.

The daily requirement for carbohydrates for an adult engaged in mental or light physical labor is 300-500 g / day. In people engaged in heavy physical labor, the need for carbohydrates is much higher. In obese people, the energy content of the diet can be reduced by the amount of carbohydrates without compromising health.

Bread, cereals, pasta, potatoes, sugar (net carbohydrate) are rich in carbohydrates. An excess of carbohydrates in the body disrupts the correct ratio of the main parts of food, thereby disrupting the metabolism.

vitamins

Vitamins are not energy providers. However, they are necessary in small amounts to maintain the normal functioning of the body, regulating, directing and accelerating metabolic processes. The vast majority of vitamins are not produced in the body, but come from outside with food.

With a lack of vitamins in food, hypoavitaminosis develops (more often in winter and spring) - fatigue increases, weakness, apathy are observed, efficiency decreases, body resistance decreases.

The actions of vitamins in the body are interconnected - the lack of one of the vitamins entails a metabolic disorder of other substances.

All vitamins are divided into two groups: water soluble vitamins And fat soluble vitamins.

Fat soluble vitamins- vitamins A, D, E, K.

Vitamin A- affects the growth of the body, its resistance to infections, it is necessary to maintain normal vision, the condition of the skin and mucous membranes. Rich in vitamin A fish fat, cream, butter, egg yolk, liver, carrots, lettuce, spinach, tomatoes, green peas, apricots, oranges.

Vitamin D- promotes education bone tissue stimulates the growth of the organism. A lack of vitamin D in the body leads to disruption of the normal absorption of calcium and phosphorus, causing rickets. Vitamin D is rich in fish oil, egg yolk, liver, fish roe. There is little vitamin D in milk and butter.

Vitamin K- participates in tissue respiration, blood clotting. Vitamin K is synthesized in the body by intestinal bacteria. The cause of vitamin K deficiency is diseases of the digestive system or intake antibacterial drugs. Vitamin K is rich in tomatoes, green parts of plants, spinach, cabbage, nettles.

Vitamin E(tocopherol) affects activity endocrine glands, on the exchange of proteins, carbohydrates, provides intracellular metabolism. Vitamin E favorably affects the course of pregnancy and fetal development. Vitamin E is rich in corn, carrots, cabbage, green peas, eggs, meat, fish, olive oil.

Water Soluble Vitamins- vitamin C, B vitamins.

Vitamin C (ascorbic acid) - actively participates in redox processes, affects carbohydrate and protein metabolism increases the body's resistance to infections. Rich in vitamin C, rose hips, black currants, chokeberry, sea buckthorn, gooseberry, citrus fruits, cabbage, potatoes, leafy vegetables.

To the group vitamins B includes 15 independent vitamins, soluble in water, which take part in the metabolic processes in the body, the process of hematopoiesis, play an important role in carbohydrate, fat, water metabolism. B vitamins are growth promoters. Brewer's yeast is rich in B vitamins, buckwheat, oat groats, Rye bread, milk, meat, liver, egg yolk, green parts of plants.

Microelements and macroelements

Minerals are part of the cells and tissues of the body, are involved in a variety of metabolic processes. Macronutrients are needed by the body in relatively large quantities: calcium, potassium, magnesium, phosphorus, chlorine, sodium salts. Trace elements are needed in very small quantities: iron, zinc, manganese, chromium, iodine, fluorine.

Iodine is found in seafood, cereals, yeast, legumes, and liver are rich in zinc; copper and cobalt are found in beef liver, kidneys, yolk chicken egg, honey. Berries and fruits contain a lot of potassium, iron, copper, phosphorus.

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Food products are necessary for the body for growth, the formation of new cells to replace those that have expired and died, as well as to replenish the energy reserves necessary for life and procreation. The total amount of food products entering the body and assimilated nutrients and energy should correspond to the sum of substances and energy costs spent on the formation of new tissues, as well as those removed from the body.
Food in the form in which it enters the body cannot be absorbed into the blood and lymph and cannot be used to perform various vital functions. For the absorption of food in the organs digestive system it must undergo mechanical and chemical treatment. Food is crushed in the mouth, mixed in the stomach and small intestine with digestive juices, whose enzymes break down nutrients into simpler components. Digested to amino acids, monosaccharides and emulsified fats, nutrients are absorbed and absorbed by the body. Water, minerals (salts), vitamins are absorbed in their in kind. The mechanical and chemical processing of food and its transformation into substances absorbed by the body is called digestion.
All chemical compounds that are used in the body as building materials and energy sources (proteins, fats and carbohydrates) are called nutrients.
A person should regularly receive a sufficient amount of nutrients (proteins, fats and carbohydrates) with food, as well as the necessary water, mineral salts and vitamins.
Proteins contain hydrogen, oxygen, carbon, nitrogen, sulfur, phosphorus and other elements. In the stomach and small intestine, dietary proteins are broken down into amino acids and their constituents, which are absorbed and used to synthesize human-specific proteins. Of the 20 amino acids, necessary for a person, nine are essential as they cannot be synthesized in the human body. Ego valine, histidine, isoleucine, leucine, lysine, methionine, threonine, tryptophan, phenylalanine. Listed amino acids
must be ingested with food. Without these essential amino acids, the synthesis of proteins necessary for the human body is disrupted. Proteins containing a complete set of amino acids, including essential amino acids, are called biologically complete proteins. The most valuable is the protein of milk, meat, fish, eggs. Proteins of plant origin (corn, wheat, barley, etc.) are considered incomplete, since they do not contain the full set of amino acids necessary for the synthesis of human proteins.
Carbohydrates containing hydrogen, oxygen, carbon are used in the body as energy substances and for the formation of cell membranes. With food in the form of vegetables, fruits, starches and others herbal products complex carbohydrates, which are called polysaccharides, enter the body. During digestion, polysaccharides are broken down into water-soluble disaccharides and monosaccharides. Monosaccharides (glucose, fructose, etc.) are absorbed into the blood and, together with the blood, enter the organs and tissues.
Fats serve as a source of energy and are able to accumulate in the body in the form of reserve materials. Fats are part of all cells, tissues, organs, and also serve as rich energy reserves, since during starvation, energy carbohydrates are formed from fats. Fats are made up of carbon, oxygen and hydrogen complex structure. In the process of digestion, fats are broken down into their components - glycerol and fatty acids (oleic, palmetic, stearic), which are found in fats in various combinations and ratios. In the body, fats can also be synthesized from carbohydrates and protein breakdown products. Some fatty acids cannot be formed in the body. These are oleic, arachidonic, linoleic, linoleic, which are contained in vegetable oils.
Minerals also enter the body with food and water in the form of various salts. These are salts containing calcium, phosphorus, potassium, sodium, sulfur, chlorine, iron, magnesium, iodine. Many other elements are present in food in small amounts, so they are called trace elements. For a growing body mineral salts more is required than for an adult, since they are involved in the formation of bone tissue, organ growth, are part of blood hemoglobin, gastric juice, hormones, cell membranes, nerve synapses.
Water, the amount of which in an adult reaches 65% of the total body weight, is integral part tissue fluid, blood, internal environments of the body. In food, vitamins are also present in small quantities, which are complex organs.
nic connections. Vitamins are necessary for metabolic processes, they participate in all biochemical reactions, affect the growth and development of the human body and its organs. Lack or lack of vitamins in food leads to serious illnesses- avitaminosis.
Food also contains alimentary fiber, which are fiber (cellulose), which is part of plant cells. Dietary fibers are not broken down by enzymes, they are able to retain water. This is very important for digestion, since swollen dietary fibers, stretching the walls of the colon, stimulate peristalsis, the movement of food masses towards the rectum. The need for the amount of food consumed and the qualitative composition of nutrients (proteins, fats, carbohydrates, minerals and vitamins) depends on age, sex, body weight, work performed.
The amount of energy consumed in the body - energy consumption is measured in calories (or joules). One calorie is the amount of energy required to raise the temperature of water by 1°C (1 calorie is equal to 4.2 Joules - J). In the body, when 1 g of protein is oxidized, 4.1 kilocalories are formed - kcal, when 1 g of carbohydrates is oxidized - 4.1 kcal, when 1 g of fat is oxidized -

1. kcal. Worker Energy Requirements Data various kinds labor are given in table. 9.

Table 9
Daily energy requirement for persons of various categories of labor

To meet the vital needs of the body during the day with light work, food should contain at least 80-100 g of proteins, and with heavy physical exertion - from 120 to 160 g. For children, taking into account their growth and energy costs, the amount of protein in food, when calculated per 1 kg of body weight, should be more than for an adult. The total amount of animal and vegetable fats in food per day should be at least 50 g. The need for carbohydrates during the day is 400-500 g.
Types of digestion
Digestion of food - digestion is a complex process. It is carried out in the cavities of the digestive system with the participation of enzymes secreted by the digestive glands. Therefore, digestion in the stomach, small intestine is called abdominal digestion. Digestion of food also occurs directly on the surface of epithelial cells. small intestine. Such digestion is called contact or membrane digestion. The point is that on outer surface cell membrane of epitheliocytes has the most high concentration digestive enzymes secreted by the intestinal glands. Membrane digestion is, as it were, the final phase of food digestion, after which the split proteins and carbohydrates, emulsified fats are absorbed into the blood and lymphatic capillaries.
The breakdown (digestion) of proteins, fats, carbohydrates occurs with the help of digestive enzymes (juices). These enzymes are found in saliva, gastric juice, intestinal juice, bile and pancreatic juice, which are, respectively, the secretion products of the salivary, gastric, small intestine and colonic glands, as well as the liver and pancreas. During the day, approximately 1.5 liters of saliva, 2.5 liters of gastric juice, 2.5 liters of intestinal juice, 1.2 liters of bile, 1 liter of pancreatic juice enter the digestive system.
Enzymes are the most important components of the secretions of the digestive glands. Thanks to digestive enzymes, proteins are broken down into amino acids, fats into glycerol and fatty acids, carbohydrates into monosaccharides. Digestive enzymes are complex organic substances that easily enter into chemical reactions with food products. Enzymes also serve as accelerators (catalysts) of biological reactions - the breakdown of nutrients. Produce enzymes that break down proteins
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proteases, splitting fats - lipases, splitting carbohydrates - amylases. For splitting actions, certain conditions are necessary - body temperature and the reaction of the environment (acidic or alkaline).
The organs of the digestive system also perform a motor (motor) function. In the digestive organs, food is crushed and mixed with digestive juices, which ensures close contact of food masses with enzymes. Mixing food with simultaneous promotion contributes to its continuous and close contact with the absorption surface of the intestine and more complete absorption of the digested food components. The promotion of food masses in the direction of the rectum contributes to the formation stool and ends with their removal from the body.