Energy value and qualitative composition of the diet. The role of protein in nutrition

In therapeutic and dietary nutrition, it is necessary to maintain the optimal chemical balance of essential nutrients, depending on the nature of the disease and its stage. The diet should contain proteins, fats, carbohydrates, vitamins, minerals and water - in quantities depending on the nature of the diet.

Proteins are vital substances for the body, providing it primarily with building material. Proteins are involved in the formation of enzymes, hemoglobin, hormones and other compounds without which the body cannot function. Proteins form compounds responsible for immunity to various infections; proteins are involved in the process of assimilation of fats, carbohydrates, microelements and vitamins. Unlike carbohydrates, proteins do not accumulate in the body and are not formed from other food elements, therefore they are indispensable in the human diet. When choosing a diet, not only the amount of protein is taken into account, but also its qualitative composition. Food proteins are made up of amino acids, each of which has its own meaning. Many of them are irreplaceable, since they are not formed in the body and must be supplied as part of food products. The greatest biological value is characterized by those proteins in which the amino acid content is balanced and corresponds to certain ratios. The lack of several amino acids or even one of them reduces the biological value of the protein. Proteins with high biological value are easily absorbed and well digested. These are primarily the proteins of milk, eggs, meat and fish (without connective tissue). The proteins of milk and fish are digested most quickly, then the meat proteins of beef, pork and lamb, and the proteins of bread and cereals more slowly. Collagen is obtained from the protein of connective tissue, cartilage and bones - gelatin that dissolves in water when heated and promotes blood clotting. Gelatin dishes are easily digestible and useful after operations and for gastrointestinal bleeding.

Insufficient protein intake from food, as well as the predominance of proteins with low biological value in the diet can cause protein deficiency in the body. In this case, there is a deterioration in digestion, functions of the pancreas and liver, disruption of the activity of the endocrine, hematopoietic and other body systems. Muscle atrophy, decreased immunity, and hypovitaminosis are often observed. Such deviations occur when the principles of rational nutrition are violated, long-term adherence to monotonous diets and fasting for the purpose of losing weight. However, more often protein deficiency is caused by diseases of the digestive system, increased protein consumption in active forms of tuberculosis, complex injuries and operations, malignant tumors, extensive burns, blood loss, and kidney disease. Excessively long or incorrectly selected low-protein diets for nephrotic syndrome and liver diseases can also lead to protein deficiency.

Excess protein in the diet also has a negative effect on the body. At the same time, the liver and kidneys are overloaded with protein breakdown products, the digestive organs are overstrained, the intestines suffer due to the activation of putrefactive processes, and the body’s acid-base state shifts to the acidic side due to the accumulation of nitrogen metabolism products.

The daily protein requirement of a healthy person is 80-100 g, the share of animal proteins in the diet should be 55%. In some diseases, in particular renal failure and acute nephritis, the amount of protein consumed in food is reduced to 20-40 g; of this amount, 60-70% of proteins can be of animal origin. The protein content of products can be determined using special tables or by studying the information on the packaging of prepackaged products.

Fats play an important role in human nutrition, being the most important source of energy (1 g of fat provides 9 kcal). Fats also perform a plastic function - they are part of cells and cellular structures, and actively participate in metabolism. Together with fats, the body receives many essential substances: essential fatty acids, lecithin, vitamins A, D, E, K. Fat fiber is an active depot that provides the body with energy when needed. The taste of food improves if it contains fats, and the feeling of fullness comes faster when eating such food.

Fats are often called lipids. Their nutritional value depends on many factors. It is known that all fats are divided into two groups - neutral fats, consisting of glycerol and fatty acids, and fat-like substances - phospholipids and sterols. Fatty acids are saturated (with hydrogen) and unsaturated. The more saturated fatty acids a fat contains, the higher its melting point, the longer it takes to digest in the gastrointestinal tract, and the more difficult it is to absorb. Therefore, dietary fats that are liquid at room temperature are more valuable - most vegetable oils, milk and fish fats containing unsaturated fatty acids. Dairy fats are also sources of vitamins A, D and carotene, and vegetable oils contain a lot of vitamin E.

The nutritional value of fats largely depends on their degree of freshness. Fats easily deteriorate when stored in heat and light; when exposed to excessive heat, vitamins and essential fatty acids are destroyed. Low-quality and overheated fats are prohibited in medical nutrition, as they contain harmful substances that cause irritation of the gastrointestinal tract and disruption of the kidneys and metabolism in general. High-quality fats containing valuable unsaturated acids should be consumed in moderation. An unjustified increase in the proportion of fats in the diet, especially of animal origin, leads to the development of obesity, cholelithiasis, atherosclerosis, and coronary heart disease. Currently, there is an increased consumption of fats, sometimes their share in the energy value of the daily diet reaches 40%. It must be remembered that excess fat in food inhibits the secretion of gastric juice, impairs the absorption of proteins, calcium, magnesium, and increases the body's need for vitamins involved in fat metabolism. Increased fat consumption causes overstrain of the functions of many organs and systems. As a result, digestive disorders occur and pancreatitis, enterocolitis, liver and biliary tract diseases develop. Eating foods containing a small amount of fat, for example, butter of the “Krestyanskoe” and “Buterbrodnoe” varieties, creamy confectionery products and plant-based creams, low-fat kefir and sour cream, sausages with reduced fat content and full-fat, will help bring your diet closer to rational. content of proteins and other dietary products. On average, a healthy person needs 80-100 g of fat per day, depending on age and the nature of physical activity, of which a third should be vegetable fats. If there is a need for therapeutic nutrition for diseases of the liver, biliary tract and intestines, obesity, diabetes mellitus, gout, anemia, hypothyroidism, coronary heart disease, atherosclerosis and chronic pancreatitis, this amount decreases or the qualitative composition of fats changes. The fat content in the diet is increased due to easily digestible milk and vegetable fats in case of exhaustion after serious illnesses, tuberculosis, hyperthyroidism and some other diseases.

Carbohydrates make up the bulk of our diet. We can say that the nutrition of modern man is carbohydrate-oriented. The share of carbohydrates in the total energy value of the daily diet is 50-60%. Carbohydrates contribute to the proper metabolism of proteins and fats, form hormones and enzymes, secretions of various glands and other important biological compounds in combination with proteins. Non-digestible ballast substances (fiber and pectins) contained in carbohydrates, although not digested in the intestines and are not a source of energy, play an important role.

Carbohydrates are found mainly in plant foods. They are divided into simple and complex, digestible and indigestible. Simple carbohydrates (glucose, fructose, galactose, sucrose, lactose, maltose) are absorbed well, especially quickly - glucose, slower than fructose. Sources of these valuable dietary nutrients are honey, fruits, berries, and some vegetables. Glucose and fructose serve as the main sources of energy, in particular for brain function, as well as for the formation of reserve carbohydrate (glycogen) in the liver and muscles. The peculiarity of fructose is that its absorption does not require the hormone insulin, which makes it possible to consume fructose-containing foods for diabetes. During absorption in the intestine, sucrose is broken down into glucose and fructose. Sources of sucrose are sugar, jam, confectionery, ice cream, fruits, and some vegetables. Lactose (milk sugar) is found in dairy products and is broken down into glucose and galactose in the intestines. In the case of congenital or acquired during intestinal diseases, a violation of this breakdown of lactose is observed into milk intolerance with abdominal pain, bloating, and diarrhea. In such situations, it is recommended to consume fermented milk products, in which lactose is converted into lactic acid during fermentation. Maltose (malt sugar) is found in free form in honey, beer, malt milk, molasses; as an intermediate product, it is obtained during the digestion of starch in the intestines with the participation of digestive enzymes and malt enzymes (sprouted wheat grains).

Complex carbohydrates, also called polysaccharides, are starch, glycogen, fiber, and pectin. Their importance in human nutrition is very great.

Starch supplies about 80% of carbohydrates in the diet, being included in large quantities in everyday products (wheat and rye flour, buckwheat, pearl barley, semolina, wheat, rice, oatmeal, peas, beans, pasta, cookies, potatoes, etc.) . Starch, which is part of different foods, breaks down into glucose in the digestive tract at different rates (depending on the product). Starch in its natural form is absorbed more easily and quickly in jelly, as part of rice, semolina and potato dishes. Eating foods rich in starch is much healthier than consuming sugar, since in the first case the body receives, along with carbohydrates, minerals, B vitamins, fiber and pectins, which are necessary for normal functioning. Fiber and pectins, the so-called ballast substances, are in fact as necessary as other biologically important elements included in food products. Fiber (cellulose) is the membrane of plant cells, pectins are substances that connect these cells to each other. Their role is to stimulate intestinal motility, bile secretion, and remove cholesterol from the body. Ballast substances create a feeling of fullness and form feces. A large amount of fiber is found in wheat bran, nuts, raspberries, beans, strawberries, dates, oatmeal, black currants, raisins, fresh mushrooms, cranberries, gooseberries, prunes, figs, chocolate, buckwheat, pearl barley and barley, peas, potatoes, cabbage, eggplant and other products. Pectins regulate the course of putrefactive processes in the intestines and absorb harmful digestive waste. The beneficial property of pectins to heal the intestinal mucosa is used in the treatment of inflammatory processes. Pectins in combination with sugar and organic acids are used to prepare jellies, jams, marmalades, and marshmallows. Long-term dietary deficiency of fiber, pectin and other dietary fibers (lignin, hemicellulose, plant fibers) leads to constipation, diverticula, polyps, hemorrhoids, cancer of the colon and small intestines, and is one of the factors influencing the development of diabetes mellitus, atherosclerosis and cholelithiasis diseases. Consumption of excess ballast substances leads to fermentation in the intestines, flatulence, and impaired absorption of proteins, fats and minerals.

The daily need for carbohydrates depends on the gender, age and physical activity of a person. In the diet of a healthy person, the amount of carbohydrates with a fairly active lifestyle should be 350-400 g. In the treatment of chronic nephritis, tuberculosis, hyperthyroidism, the amount of carbohydrates is increased mainly by increasing the proportion of starch. Reducing the proportion of carbohydrates, especially easily digestible ones, is recommended for diabetes mellitus without insulin therapy, obesity, atherosclerosis, allergies, chronic pancreatitis, coronary heart disease, hypothyroidism, after surgery on the gallbladder or stomach, and when taking corticosteroid hormones.

With an unreasonably low intake of carbohydrates from food into the body, hypoglycemia occurs (a decrease in blood glucose levels). The central nervous system is especially affected: weakness, sweating, trembling hands, drowsiness, nausea, headache, and an irresistible feeling of hunger occur. Even with long-term treatment of obesity, the amount of carbohydrates in the daily food intake should not be less than 100 g. Hypoglycemia often occurs due to improper nutrition of diabetic patients receiving insulin. When following any diet, it is recommended to gradually, over two to three weeks, reduce the amount of carbohydrates to improve the body’s adaptation to metabolic changes.

Excessive carbohydrate consumption is common. Against the background of an excessive increase in the energy value of food, metabolic disorders develop, leading to a number of diseases. Therefore, in therapeutic and dietary nutrition, much attention is paid to reducing the proportion of easily digestible carbohydrates in the diet and sufficient intake of dietary fiber. Eating large amounts of sugar frequently increases your blood glucose levels (hyperglycemia). This leads to changes in the cells of blood vessels and promotes the clumping of platelets in the blood, which creates a risk of developing thrombosis. Exhaustion occurs due to overload of pancreatic cells that produce the hormone insulin, which is necessary for the absorption of glucose. Excess carbohydrates increases the body's sensitivity to various allergens, which often leads to allergic conditions and complications in infectious and allergic diseases. Sugar and other carbohydrates in themselves are not a source of threat to the body, but are a valuable source of energy; carbohydrates must be present in the diet in the amount necessary for a healthy or sick person.

The importance of proteins in the diet of sick and healthy people
Protein is the most important component of food products. Chemically, proteins are complex nitrogen-containing biopolymers, the monomers of which are amino acids. It is the nitrogen content that distinguishes proteins from other organic substances. Proteins are high molecular weight compounds. The amino acid composition of different proteins is not the same and is an important characteristic of each protein and a criterion for its nutritional value. Each amino acid has a strictly defined meaning in the synthesis of tissue proteins. Proteins are divided into simple and complex. Simple proteins contain only amino acids, or the protein portion. Complex proteins, in addition to amino acids, contain a non-protein part, or prosthetic group. Depending on their spatial structure, proteins are divided into globular (their molecules have a spherical shape) and fibrillar (their molecules have a thread-like shape). Simple globular proteins include albumins and globulins, which are widespread in nature and are found in milk, blood serum, and egg whites. Many structural proteins are fibrillar proteins of animal origin and perform a supporting function in the body. These include keratins (proteins of hair, nails, epidermis), elastin (protein of ligaments, connective tissue of blood vessels and muscles), collagen (protein of bone, cartilage, loose and dense connective tissue). Based on the content of certain amino acids, proteins are divided into biologically complete and incomplete. Biologically complete proteins contain essential amino acids, i.e. those that are not synthesized in the body and enter it only with food. These include tryptophan, leucine, isoleucine, valine, methionine, threonine, lysine, phenylalanine, histidine and arginine. Incomplete proteins do not contain essential amino acids.

Proteins perform numerous functions in the body.

1. Plastic function. Proteins make up about 20% of the mass of various tissues (fats and carbohydrates - 3%) and are the main building material of the cell and intercellular substance. Proteins are part of all biological membranes, which play a very important role in the construction of cells.

2. Hormonal function. A significant portion of hormones are proteins. These include parathyroid hormone and pituitary hormones.

3. Catalytic function. Proteins are components of all currently known enzymes. In this case, simple enzymes are pure proteins. Complex enzymes, in addition to proteins, also include other components - coenzymes. Enzymes play an important role in the assimilation of food products by the human body and in the regulation of all intracellular metabolic processes.

4. Specificity function. The great diversity and uniqueness of proteins provide tissue and species specificity, which underlies the manifestations of immunity and allergies. In response to the entry of foreign proteins - antigens - into the body, active synthesis of antibodies occurs in the immunocompetent organs, which are a special type of globulins (). It is the specific interaction of the antigen with the corresponding antibodies that forms the basis of immune reactions that protect the body from foreign antigens.

5. Transport function. Proteins are involved in the transport of oxygen (hemoglobin), lipids, carbohydrates, vitamins, hormones, and medications in the blood. Specific carrier proteins ensure the transport of various mineral salts and vitamins across cell membranes.

6. Energy function. This function is of secondary importance, since the main energy processes in the human body are carried out mainly by fats and carbohydrates. The energy value of 1 g of protein is 4.1 kcal.

The minimum amount of protein required to carry out basic life processes in the body is called the nitrogen minimum and is 25 g of protein for an adult. However, to maintain normal nitrogen balance, the body needs up to 14 g of nitrogen per day, which corresponds to 90 g of protein. This minimum cannot be replaced by either fats or carbohydrates, since they do not contain nitrogen and cannot be converted into proteins. In the complete absence of protein foods in the diet, even with excess consumption of fats and carbohydrates, the breakdown of its own tissue proteins constantly occurs, which invariably leads the body to death.

A healthy person is characterized by a state of equilibrium nitrogen balance, in which the amount of nitrogen entering the body with food is equalized by the amount of nitrogen lost by the body in feces, urine and other natural wastes. With the intensification of protein breakdown processes and its predominance over synthesis, a negative nitrogen balance arises, characterized by predominant processes of loss of nitrogenous bases. Negative nitrogen balance is observed with complete or partial fasting, consumption of low-protein diets, impaired absorption of proteins in the gastrointestinal tract, and various diseases (tuberculosis, burn disease, cancer). With prolonged restriction of protein content in the diet, severe changes develop in the body: general weakness develops, performance is impaired, and the body’s resistance to edema decreases. Positive nitrogen balance is most often observed in children and adolescents, as well as in people recovering from illness.

Excessive intake of protein from food is also unsafe for the body, as it causes overload of various organs (liver and kidneys), leads to the accumulation of nitrogenous waste in the body, and the development of putrefactive processes in the intestines, which is manifested by symptoms of putrefactive dyspepsia.

The work of many domestic scientists has proven that the optimal protein norm for ensuring normal life activity and growth needs for an adult performing light work is 120 g of protein per day. For people with heavy physical labor, this figure is 160 g. Children, pregnant and lactating women, and feverish patients need to increase the usual standards. There are a number of diseases (nephrosis,) where increased protein nutrition is one of the main methods of treatment. This is explained by the fact that with nephrosis, the release of proteins from the body increases, and with obesity, increased protein nutrition will stop the progression of this disease, increase basal metabolism, and will promote. In diseases that are associated with impaired nitrogen metabolism, which is often associated with insufficient (chronic nephritis, nephroangiosclerosis), the protein content in food should be kept to a minimum.

When constructing a rational diet, it is necessary to take into account not only the total amount of proteins included in it, but also their qualitative composition, and take into account the provision of a minimum of biologically complete proteins. It must be remembered that complete proteins can also manifest themselves as inferior if they are taken in insufficient quantities. Conversely, two incomplete proteins containing different amino acids can satisfy the body's protein needs. Proteins of animal origin are the most complete, and it is necessary that 60% of the daily protein requirement comes from them. The qualitative composition of proteins is of particular importance in long-term patients, since immune processes depend on this; on the other hand, these patients lack immunity and are forced to eat monotonous food for a long time. Thus, the diet of a healthy and especially a sick person should have an optimal protein content not only in quantitative, but also in qualitative composition.

The main elements of food include proteins, fats, carbohydrates, vitamins and microelements. Let's look at the meaning of each of these components.

They are the building material for all living cells. Without them, human existence is impossible. All proteins are divided into simple (proteins) and complex (proteids) and are complex nitrogen-containing polymers that consist of amino acids. Each protein has its own unique amino acid composition. Most often, 20 basic amino acids are found in any of them.

No other substances can replace proteins. They are associated with the implementation of all the basic manifestations of life - such as the ability to grow and reproduce, digestion, irritability and thinking. It is thanks to proteins that the transmission of hereditary information is ensured; it is in them that the individuality of each organism is manifested.

The human body, especially in childhood, has virtually no protein reserves, so their reserves must be regularly replenished thanks to the constant supply of proteins from food products. Therefore, they must be included in your baby’s daily diet.

Once in the stomach (and then in the intestines), food proteins are exposed to digestive juices and are broken down into amino acids, which are absorbed by the small intestine and enter first the liver, and then to other organs and tissues. From these, protein compounds that are characteristic only of the body are formed. In addition to the amino acids that enter the body with food, it contains free amino acids formed during the breakdown of its own proteins. All amino acids form the so-called amino acid fund, which is used in the child’s body for protein synthesis.

Our body cannot synthesize 8 out of 20 amino acids on its own, so they must be regularly supplied with appropriate foods. For children in the first year of life, histidine is an essential amino acid, and for children in the first months of life (especially those born prematurely) - cysteine ​​and tyrosine. A deficiency of any of the 20 basic acids that are involved in the protein synthesis that occurs in our body is unacceptable, since this can lead to serious disruptions in protein metabolism.

In addition to their function as building materials for organs and tissues, proteins play a role in supplying the body with energy through their oxidation. It should also be borne in mind that they begin to be intensively used as a source of energy during forced fasting, when the body experiences a relative deficiency in fats and carbohydrates. The next function of food proteins in our body is protective, which is to increase its resistance to the effects of various infectious and toxic agents, and also manifests itself in stressful situations and during neuropsychic stress.

A constant deficiency of dietary proteins leads to impaired growth and physical development of the child, and also, according to the results of recent studies, to a lag in neuropsychic development. In children of the first year of life, protein deficiency can manifest itself when the mother has insufficient milk, formulas with a reduced protein content are used for artificial feeding of infants, or when it is poorly absorbed due to disturbances in protein and amino acid metabolism. In addition, untimely and irrational introduction of complementary foods can lead to protein deficiency. At an older age, the reasons for its appearance may be the low energy value of the children's diet or diseases that are accompanied by disturbances in the processes of digestion and absorption of proteins and amino acids.

Excessive (compared to physiological norms) intake of proteins into the body is also undesirable for the child’s body. This causes increased work of the digestive tract and significant activation of amino acid metabolism and urea synthesis in the liver, and also increases the load on the kidneys, which begin to intensively secrete the end products of nitrogen metabolism. With excessive consumption of proteins, the products of their rotting and incomplete breakdown accumulate in the gastrointestinal tract, which can lead to the development of intoxication in a child. Increased intake of proteins into the body of children in the first year of life often becomes one of the causes of obesity and constipation.

Thus, only the intake of dietary proteins that strictly corresponds to the physiological needs of the child can ensure the maintenance of his health. In table Table 1 shows the recommended average daily norms of physiological protein requirements for children of different ages. However, there are special cases when its quantity has to be increased or, conversely, limited.

It is recommended to increase the consumption of protein foods for various diseases (severe infections, gastric and duodenal ulcers, chronic enteritis and pulmonary tuberculosis), as well as after surgery and injuries. Limiting the level of protein in baby food is also indicated for severe forms of renal failure.

It should be noted that for a person (especially in childhood) it is important not only the amount of proteins consumed in food, but also their quality (biological value), which is determined by their amino acid composition. The closer the composition of amino acids in food proteins is to the composition of proteins in the human body, the higher it is. The value of protein also depends on the content of essential amino acids in it and their ratio to each other. In terms of amino acid composition, the proteins found in meat, fish, milk, dairy products and eggs are closest to the proteins of the human body. They have the highest nutritional value, so mother’s milk is the ideal food product for a baby in the first year of life. This is explained by the fact that the biological value of its proteins is maximum, and its amino acid composition ideally meets the needs of the baby.

An important indicator of dietary protein is also the degree of its digestibility. Based on the speed of digestion, all food proteins can be divided into 3 groups. Fish and milk proteins are digested the fastest, meat proteins a little slower, and bread and cereal proteins even slower. Many plant foods, especially grains, contain proteins that have reduced nutritional value. In table Table 2 shows the protein content in basic foods.

table 2

In order to fully satisfy the needs of a growing child's body for amino acids, it is advisable to introduce into the child's diet combinations of products that complement each other. The most favorable is the combination of plant and dairy products. Flour products with cottage cheese (dumplings, cheesecakes, etc.) and flour dishes with meat also have an optimal amino acid formula. To increase the digestibility of proteins by the child’s body, it is also necessary to give him not only cereals and flour, but also vegetable dishes containing extractives, mineral salts and vitamins, which contribute to better digestibility of food.

Squirrels- organic nitrogen-containing compounds consisting of amino acids. All life processes in the human body are closely related to proteins: metabolism, muscle contraction, growth and development, and even the highest form of movement of matter - the process of thinking.

There is practically no reserve of protein in the human body; its only source is proteins that come from food.

Main functions of protein:

1. Plastic or construction- construction of new cells and tissues, primarily for a young growing organism, and in adulthood their regeneration.

2. Catalytic. All enzymes are simple or complex proteins. So, all biochemical reactions that occur in the human body are catalyzed by enzyme proteins.

3. Contractile. Any type of movement in a living organism is carried out by protein structures of cells - actomyosin.

4. Transport. Blood protein - hemoglobin transports oxygen from the lungs to organs and tissues. Transport of fatty acids and hormones occurs with the participation of the blood serum protein albumin.

5. Protective. The most important factors of immunity (antibodies and the complement system) are proteins. The blood clotting process, which protects the body from excessive blood loss, occurs with the participation of a serum protein - fibrinogen. The inner walls of the esophagus and stomach are covered with a protective layer of mucous proteins - mucins. The basis of the skin, which protects our body from many external factors, is the protein collagen.

6. Hormonal. A number of hormones in their structure belong to proteins (for example, insulin) or to peptides (ACTH, vasopressin, oxytocin, etc.).

7. Support. Tendons, joints, and skeletal bones, which perform a supporting function in the body, are mainly proteins.

8. Energy. When 1 g of protein is burned in the body, 4 kcal of thermal energy is released.

9. Receptor. Many proteins (especially glycoproteins and lectins) perform the very important function of recognizing and attaching various substances.

Amino acids and their importance in nutrition

Amino acids- these are the main components and structural components of proteins. Currently, more than 130 amino acids have been described. Food contains only 20 - glycine, alanine, isoleucine, leucine, valine, serine, threonine, asparagine, glutamine, arginine, lysine, cysteine, cystine, methionine, phenylalanine, tyrosine, tryptophan, histidine, proline, hydroxyproline.

Amino acids according to their biological value are divided into two groups: replaceable and irreplaceable. Nonessential amino acids can be synthesized in the body, but essential amino acids are not synthesized or are not synthesized enough by the body. Essential amino acids include tryptophan, lysine, leucine, isoleucine, methionine, phenylalanine, threonine and valine. Arginine and histidine are essential amino acids in children.

Proteins that contain all essential amino acids in optimal proportions are classified as full-fledged. Complete proteins found in most animal products (meat, fish, dairy products, eggs). Proteins that do not contain all essential amino acids or are poorly balanced are classified as not complete.

Daily requirement. In a person’s daily diet, depending on age, gender, energy activity, the amount of protein is from 0.75 to 1.5?. per 1 kg body weight. The need for proteins increases with increasing energy expenditure, since individuals performing heavy physical work have a high rate of tissue wear. Need children in protein is 2.5-4 g and kg body weight. The need for proteins increases during stress, infectious diseases, injuries, insomnia, and overheating.

Sources of protein. The greatest amount of proteins is found in legumes (20-35%), hard cheese (26%), meat and fish (10-20%), less in cereals (9-15%), baked goods (6-8%) and absolutely little - in vegetables (up to 2%), fruits, berries (up to 1%).

To meet the body's needs for all amino acids in the diet of adults, about 50% of proteins must be covered by products of animal origin, and in the diet of children this percentage increases to 70%.

Protein deficiency divided into protein deficiency only and protein-energy deficiency.

A pathology associated not only with protein deficiency, but also widespread in underdeveloped countries (Africa, Asia), especially among children under 4 years of age, the disease is kwashiorkor. Kwashiorkor is characterized by a tetralogy of Djelifa. Edema, growth retardation, mental changes, muscle atrophy. Protein-energy deficiency manifests itself in the form of nutritional dystrophy or nutritional insanity.

Excessive intake of animal proteins in the diet leads to the development of gout. This is due to the formation of large amounts of urea and uric acid, the salts of which are deposited in the joints.

Calculation methods for determining energy value and nutrient content

composition of the diet

Methods of balance and budget nutrition research, based on the assessment of food allocations for organized groups or the profits of a family or individual, allow only an approximate assessment of the nutrition of these groups of people.

Questionnaire and weight methods make it possible to more accurately determine the amount of food consumed, but they also do not make it possible to assess the qualitative composition of the daily diet.

Laboratory methods for determining the energy value and nutrient composition of the daily diet are the most accurate, but require complex, time-consuming research and significant material costs, which limits their systematic use in medical monitoring of nutrition of different categories of the population.

Calculation methods are quite accurate, accessible with constant, systematic medical monitoring of nutrition of different categories of the population, do not require additional material costs, and, if computer technology is available, do not require significant time for calculations.

To assess the actual nutrition of organized groups, calculation methods are used:

Physiological nutritional standards, scientifically based and developed for certain categories of the population;

The food layouts (menu layouts) developed on their basis are a team nutrition plan, usually for a week;

Tables of the chemical composition of food products - reference materials on the energy value and nutrient composition of each food product.

When developing a menu layout, the need for dietary diversity and its daily usefulness is taken into account, which is achieved by multiplying the daily quantities of each product (except for those consumed equally every day, such as bread) by 7 days, after which different dishes are planned for the whole week. At the same time, the same dish should not be repeated more than three times a week.

For example, the one-day norm for cereals is 40 g, pasta - 60 g. For a week, this will be 280 g and 420 g, respectively. This allows you to plan different dishes on different days, thereby achieving a variety of nutrition and preventing the diet from becoming boring.

The responsibilities of the doctor who is responsible for the medical supervision of the nutrition of this team when creating the menu layout are:

Evaluating dishes in terms of energy value and nutrient content - proteins, fats, carbohydrates, vitamins, minerals, flavoring substances;

Providing a variety of meals throughout the week;

Supervision over the correct replacement of individual food products in their absence;

Correct accounting of food waste (which is shown in special tables);

Correct distribution of dishes and individual food products, taking into account their energy and nutritional value for individual meals, etc.

The energy value and nutrient composition of each product in the menu layout is calculated by proportion, using the “Tables of the chemical composition of food products” (Appendix 3), which shows the calorie content and content of all nutrients in 100 g of product.

To determine the ratio of nutrients (proteins and fats) of animal and plant origin, their quantity is calculated separately, or only the total quantity and quantity of animal proteins (fats) are indicated, while the quantity of vegetable proteins (fats) is determined by subtracting the number of animals from the total amount of proteins (fats) ).

The distribution of the daily diet among individual meals, based on its energy value, is determined as a percentage. At the same time, they recommend 30% of calories for breakfast, 40-45% for lunch, 20-25% for dinner. With four meals a day, a second breakfast is allocated - 10-12% due partly to breakfast, partly to lunch.

The conclusion on the assessment of the team’s nutrition should cover the following basic questions:

1) Correspondence of the energy value and quantity of all nutrients (proteins, fats, carbohydrates, vitamins, minerals, trace elements) to energy expenditure and physiological needs for them (calculated by students in the previous lesson) and nutritional standards (see Appendix 2 of the next lesson).

2) Correspondence to the physiological needs of the ratios between animal and vegetable proteins, fats, between complex and simple carbohydrates. According to physiological standards, as stated above, animal proteins should account for at least 55% of their total energy value, vegetable fats - at least 30%; mono-, disaccharides - no more than 18-20%.

3) Sufficiency of vitamins in the diet, taking into account their inevitable losses during culinary processing of food products, the correct ratio between vitamin A and carotene.

4) Sufficiency of minerals, especially Ca, P, their ratio, Fe, and microelements. Availability of spices and flavorings.

5) Repeatability of dishes during the week (diversity of food).

6) Based on the identified deficiencies, recommendations are made regarding the optimization of the layout of products, especially taking into account the expected changes in the physical activity of the controlled team.

For ease of analysis, the results of calculations of the nutrient composition and energy value of the diet according to the menu layout are entered into the table (Appendix 2).

Appendix 2

Results of assessment of nutrient composition and energy value

student diet