Plastic or qualitative adequacy - the food taken must contain the ingredients necessary for life in a balanced ratio of proteins, fats, carbohydrates, minerals and ballast components (1: 1.2: 4.6, 13%: 30%: 57%).

Postulate of the theory of adequate nutrition:

    necessary food components - nutrients and ballast substances

Essential nutrients are not synthesized or stored in the body, so they must be strictly rationed.

To essential nutrients, which are not formed in the body or are formed in insufficient quantities, include:

    complete proteins (containing essential amino acids),

    complete fats (containing unsaturated and polyunsaturated fatty acids),

    vitamins,

    minerals

Intake of essential nutrients from food is mandatory.

Needed for nutrition and replaceable nutrients, since if there is a lack of the latter, other nutrients, including essential ones, are consumed for their role in the body.

Classification nutrients:

Essential amino acids: methionine, lysine, tryptophan, phenylalanine, leucine, isoleucine, threonine and valine, sometimes also tyrosine and cystine.

Essential fatty acids

    α-linolenic acid (omega-3 fatty acid with the shortest chain),

    linoleic acid (omega-6 fatty acid with the shortest chain).

Vitamins

    biotin (vitamin B7, vitamin H),

    choline (vitamin Bp),

    folate (folic acid, vitamin B9, vitamin M),

    Niacin (vitamin B3, vitamin P, vitamin PP),

    pantothenic acid (vitamin B5),

    riboflavin (vitamin B2, vitamin G),

    thiamine (vitamin B1),

    vitamin A (retinol),

    vitamin B6 (pyridoxine, pyridoxamine or pyridoxal),

    vitamin B12 (cobalamin),

    vitamin C (ascorbic acid),

    vitamin D (ergocalciferolylcholecalciferol),

    vitamin E (tocopherol),

    vitamin K (naphthoquinones).

Essential mineral salts:

    Potassium (hypo/hyper-kalemia)

    Chlorine (hypo-/hyer-chloremia)

    Sodium (hypo/hyper natremia)

    Calcium (hypo/hypercalcemia)

    Phosphorus (hypo/hyperphosphatemia)

  • Iron (anemia/iron metabolism disorder)

    Manganese

    Molybdenum

Replaceable (some amino acids, lipids, carbohydrates) are those that can be formed in the body from other substances. For example, human cells can synthesize any monosaccharide they need from amino acids, fats can be formed from carbohydrates, some amino acids are formed from other amino acids or from carbohydrates.

6.Proteins and their role in nutrition. Source of income. Establishment of the biological value of proteins. Principles of protein rationing in the population's diet.

Squirrels food (proteins) They perform a predominantly plastic function in the body: they are necessary for the growth and renewal of all cells and tissues of the body, the synthesis of antibodies, many enzymes and hormones.

Protein source: animal meat, fish, poultry, eggs, baked goods, grain products (cereals, pasta), beans, seeds, nuts.

Biological role of food proteins is that they serve as a source of irreplaceable and replaceable amino acids. Amino acids are used by the body for

    synthesis of own proteins;

    as precursors of non-protein nitrogenous substances (hormones, purines, porphyrins, etc.);

    as a source of energy (oxidation of 1 g of proteins provides approximately 4 kcal of energy).

The nutritional and biological value of proteins is determined by the required amount of amino acids entering the body with food and their balance.

The main criterion in assessing the biological value and physiological role of amino acids is their ability to support growth and ensure protein synthesis.

Food protein quality(biological value of protein - degree of utilization of protein nitrogen by the body) due to the presence in it of a complete set of essential amino acids in a certain quantity and in a certain ratio with non-essential amino acids.

For an adult, the aminogram recommended by the FAO/WHO Committee is used as an “ideal” protein that is 100% utilized in the body, showing the content of each of the essential amino acids (g) in 100 g of standard protein and the daily requirement for it. The closest to the ideal protein: breast milk!!!, animal proteins of meat, eggs, milk.

Food proteins are divided into complete and incomplete.

Complete food proteins - of animal origin, contain all amino acids in the required proportions and are well absorbed by the body.

Incomplete proteins - plant origin, do not contain, or contain insufficient amounts of one or more essential amino acids.

The quality of a food protein can be assessed by comparing its amino acid composition with the amino acid composition of an “ideal” protein by calculating its amino acid score.

Amino acid score (ASC) is the percentage ratio of the amount of each amino acid (g) in 100 g of protein of the product under study to the amount of the same amino acid in 100 g of “ideal” protein. Limiting biological value protein is the amino acid with the lowest rate.

The body's protein supply is assessed using the determination method nitrogen balance(equilibrium) between the amount of nitrogen obtained from food proteins and the amount of total nitrogen losses in the body with excretory products.

Nitrogen balance- this is the amount of nitrogen received from food and is equal to the amount of nitrogen excreted from the body (with urine, feces, sweat, hair, nails)

Positive nitrogen balance characteristic of children due to growth, development

Negative nitrogen balance characteristic of complete or partial fasting, consumption of low-protein diets, impaired absorption of proteins in the gastrointestinal tract, during illness

Daily requirement: at least 50 g per day, on average 80-100 g.

1) food energy from proteins - 11-15% of the total energy value daily ration (depending on age and intensity of work)

The key nutritional formula for maintaining your current body weight is that you should take in as many calories as you burn. If you want to gain weight, you need to take in a little more calories than you spend (for the life support of the body at rest and during physical activity). This is called a calorie surplus. If you plan to lose weight, you need to create a so-called calorie deficit. That is, you need to consume a little less than your body spends per day.

Replaceable and essential nutrients

Many chemicals are synthesized within the body itself. But some of them cannot come from anywhere, so we get them from food. Nutrients are divided into two groups:

  • replaceable (produced in our body)
  • essential (obtained from food)

Essential substances:

  • phenylalanine
  • tryptophan
  • threonine
  • methionine
  • lysine
  • isoleucine
  • valine
  • linolenic fatty acid
  • linoleic fatty acid
  • minerals

Nutrient standards

The science of nutrition studies studies metabolism. Thanks to it, it is possible to develop physiological norms for the needs of the body of an adult or child for certain nutrients. Such norms were officially approved at the state level in the USSR in the 1930s. In 1951, these standards were changed. Until recent years, we applied the standards of 1968. But today acceleration is inherent in children, and the conditions of activity and life in general for adults have changed. Therefore, these factors affected our need for nutrients.

Nutritional standards determine how many calories (read: energy) a person needs per day, exactly how much protein, fat, and vitamins. These characteristics will be different for different people. The following factors are taken into account:

  • age
  • occupation (sedentary or active)
  • features of living conditions
  • health status
  • what climate do people live in?

The concept of a balanced diet was approved in March 1982 of the last century. Every year, as researchers have determined, a person’s energy expenditure in 24 hours becomes less. Moreover, regardless of whether he lives in himself, a city or a metropolis. But hard work has not yet disappeared from human life.


Balanced nutrition by profession

A balanced diet is calculated taking into account which group a person belongs to:

  • predominantly intellectual
  • physical without much energy expenditure
  • mechanized
  • medium-heavy mechanized
  • manual heavy duty

Professions of predominantly intellectual (mental) labor:

  • engineers and technical workers whose work does not include physical activity
  • senior management of companies
  • health workers who do not perform physical work
  • educators (exception: sports educators)
  • writers
  • research scientists
  • editors and journalists of various specializations
  • cultural workers
  • secretaries, etc.

Professions of physical labor without large expenditures of energy:

  • employees whose activities are related to automated processes
  • livestock specialists
  • agronomists
  • service staff
  • physical education teachers
  • sports trainers
  • watch industry workers

Professions of mechanized labor:

  • adjusters and mechanics
  • chemists
  • printing industry workers
  • surgeons
  • food sellers
  • those who work in the catering industry
  • those whose work is related to electric transport, etc.

Professions of medium-heavy mechanized labor:

  • most machine operators and workers involved in agriculture
  • builders
  • those who work in the gas and oil industry
  • foundry workers

Professions of heavy manual labor:

  • steelworkers
  • concrete workers and masons
  • loaders who do not deal with mechanized processes
  • workers in the production of building materials who do not deal with mechanized processes, etc.

Daily caloric intake for the above groups:

As of today, nutritional standards have been received scientific basis, and not just theoretical. Our body systems primarily use carbohydrates and fats to obtain energy. When activated muscle mass In the process of our life, proteins are consumed.

In order for us to receive a sufficient amount of essential proteins, we need to consume protein of animal origin. On average, we should receive 85 g of protein per day (applies to adults). For the first group of professions, the proportion of protein in the diet should be about 13%, for the second group the percentage is 12, and for the fourth and fifth groups of professions - 11%. Animal protein should be 55% in the diet. The norm for teenagers and children is slightly higher.

The latest standards regarding the amount of fat in the diet define the daily requirement as 33% of the total nutrients. For northern countries, this norm should be slightly higher (maximum: 40%). Of all fats, thirty percent should be of plant origin.

Vegetable fats:

  • corn oil
  • sunflower oil (olija)
  • seaweed
  • greece nut
  • seeds, etc.

The latest standards developed suggest reducing the daily amount of carbohydrates consumed. The main sources of these substances are starch and sugars. The amount of sugar in products today is steadily increasing. But from a physiological point of view, it is starch that is more valuable and less dangerous. Starch is processed slowly in the gastrointestinal tract, so when we consume it we do not get a sharp jump in blood glucose. Therefore, consumption of starch, unlike sugar, does not threaten the development of such diseases as diabetes. You need to consume as little sugar as possible (mainly you need to limit confectionery products in your diet).

Vitamins

For today This is a current trend among the population of developed countries. This means that people do not receive the required set and amount of vitamins with food. The reason is that we began to eat more canned, processed foods and high-calorie dishes that contain minimal or no vitamins. Therefore, it is necessary to adjust the amount of vitamins according to the new standards.

Experts from the Institute of Nutrition claim that the consumption standards for vitamins B2, A and D in last years grew up.

Basic food products

Bread. This product contains the most carbohydrates among nutrients (from 40 to 54%). The amount of proteins is much less, it ranges from 4.7 to 8.3%. A small amount of fat: 0.6-1.3%. Bread contains vegetable proteins, which contain very small amounts of essential amino acids. Therefore, it is believed that the biological value of bread is low.

The fats contained in bread are necessary for the functioning of the liver and nervous system, and are also important for preventing the development of. Bread contains the following fatty acids:

  • palmitic
  • linoleic
  • oleic

As for carbohydrates in bread, it is mainly starch, which breaks down into glucose molecules during digestion. Bread contains a large amount of B vitamins; they cover a large percentage of the daily requirement for this vitamin.

By eating bread, we get minerals and trace elements:

  • potassium
  • sodium
  • phosphorus
  • manganese
  • iron
  • molybdenum
  • fluorine, etc.

Bread contains plant fibers that the gastrointestinal tract does not process. But they are needed for the intestines to function as they should. Black bread (rye) contains more lysine than white bread, as well as more plant fiber. The proportions of chemicals greatly depend on the quality of flour milling. Bread made from wholemeal flour is always gray and contains a large amount of minerals. Accordingly, it is better to give preference to bread made from wholemeal flour; it is healthier than bread made from premium white flour (regardless of whether you are losing weight or want to maintain your existing body weight).

If you have a lot of bread in your diet, your liver and kidneys get more work. Therefore, you do not need to eat a large amount of bread products to cover the body’s need for lysine. For this purpose, you can consume eggs, fish and meat. According to the norms, you can eat no more than 300 grams of bread per day.

Milk and dairy products. Milk does not contain absolutely all the nutrients our body needs. But this is a highly valuable product, and it should not be excluded from the diet of children, adolescents and even adults. Proteins contained in milk are considered complete proteins. When milk is consumed with bread, the proteins in the milk enrich the proteins in the bread.

Milk contains a large amount of highly digestible fats. The main fatty acids of milk: palmitic, oleic, stearic, myristic, linoleic. Milk is of maximum importance for the nutrition of newborns, who have digestive system does not function as fully as in adults.

Butter is almost entirely the fat of milk. As for carbohydrates, in milk it is mainly lactose or milk sugar. This substance is rapidly broken down in the gastrointestinal tract.

Vitamins in milk:

  • riboflavin
  • biotin
  • pantothenic acid
  • niacin
  • B12, etc.

Covering the daily requirement for minerals occurs mainly through products made from milk (yogurt, kefir, cheese, sour cream, butter, etc.). They contain a lot of calcium and potassium. Milk is also rich in phosphorus, chlorine, magnesium, sulfur, sodium, copper, iodine, iron and many other substances that are necessary for the body of a child and an adult.

Very useful and necessary for a balanced diet dairy products:

  • acidophilus
  • Ryazhenka
  • curdled milk
  • kumiss

Kumis is considered a natural antibiotic that helps get rid of many diseases. For example, they give it to patients with tuberculosis. When milk sours, caseins lose their properties and are therefore easier to process by the gastrointestinal tract. In an hour, milk is absorbed by 32 percent, and yogurt or kefir by 91 percent.

Fermented milk products kill the negative flora that multiplies in our intestines, causing dysbiosis. Therefore, for normal digestion, it is important to eat something fermented milk every day. And this applies not only to children, but also to people of any other age.

What are the benefits of cottage cheese?? It contains a lot of complete proteins, milk fat, various minerals and vitamins. Replenishing the body with calcium can be done by increasing daily consumption cottage cheese. Cottage cheese is especially important to eat for children whose skeleton is developing, as well as for older people, from whose bodies calcium is quickly washed out due to age-related changes.

Meat and meat products. Meat must be added to the diet to obtain high-value proteins and many essential amino acids. Meat is a source of lipids. In lamb, beef and pork meat, the main fatty acids are palmitic, oleic, stearic and linoleic acids. Goose and duck meat contains more unsaturated fatty acids.

Meat has very little carbohydrates, it is glycogen. It contains vitamins, as well as minerals, including trace elements:

  • potassium
  • sodium
  • phosphorus
  • iron
  • tin
  • nickel
  • chrome, etc.

Fish. Along with fish, high-value proteins enter our body. This food is a very high source of essential amino acids large quantities. Amount of fat in different types fish is different. Fatty acids in fish:

  • stearic
  • palmitic
  • oleic
  • linoleic
  • arachidonic
  • linolenic

Herring is useful because it contains a lot of vitamins A, D and E, which dissolve in a fatty environment. This fish also contains a lot of B12, sulfur, potassium and phosphorus. Many other types of fish contain trace elements in fairly high quantities:

  • iron
  • manganese
  • nickel
  • cobalt

Eggs- This is another highly valuable food product. Thanks to these products, we receive essential acids that are needed for a balanced diet. This product contains lipids. There are only 0.7% carbohydrates in eggs, which is very little, so the product is considered a protein product. It can be consumed with slow carbohydrates, for example, with buckwheat or oatmeal.

  • folacin
  • biotin
  • phosphorus
  • potassium
  • sodium

But there is relatively little magnesium and calcium in eggs. As for the content of microelements in this product, it is mainly iron and zinc. You need to eat eggs that have been processed and try not to eat them raw. You can have no more than 7-10 boiled eggs per week, because they contain quite a lot of cholesterol.

Potato, although considered second bread, has less nutritional and biological value. It contains only two percent proteins. There is also very little lipid in this product. Fatty acids are represented by oleic, linoleic and palmitic acids. Potatoes contain 19.7% of substances such as carbohydrates. The product is considered to be carbohydrate. He has minimum quantities such substances:

  • fructose
  • glucose
  • sucrose
  • hemicelluloses
  • pectin
  • cellulose
  • oxalic and citric acids
  • Apple acid

What potatoes have a lot of is vitamin C. They also contain a certain amount of pantothenic acid, niacin, thiamine, etc. By including potatoes in our balanced diet, we get more chlorine, aluminum, iron, manganese, zinc and rubidium.

Vegetables. We get vitamins, plant fibers and minerals from vegetables. Vegetables have very little fat, protein and starch, so their calorie content is minimal. Vegetables provide our body with beta-carotene, folacin, vitamin C, etc.

A large amount of folacin is found in parsley, and a little less in spinach. Beta-carotene can be obtained by adding carrots and wild garlic to your diet, as well as garlic and onions. But you shouldn’t go too far with the last two named products, because they can cause stomach diseases.

Vegetables contain potassium, zinc, iron, manganese, aluminum, as well as cellulose and pectin. They are found in beets, carrots, and cabbage.

Fruits and berries have similar nutritional value to vegetables. What distinguishes fruits from vegetables is that the former contain many mono- and disaccharides, mainly fructose. Vitamin C is easier to get from fruits than vegetables. For this you need to eat rose hips, sea buckthorn, black currants, oranges and strawberries. As for minerals, we mainly get potassium from fruits.

Mushrooms. Mushrooms contain small amounts of incomplete proteins. Lipids are also less than one percent in mushrooms. There is a lot of plant fiber in this product. Mushrooms contain the following beneficial substances:

  • niacin
  • vitamin C
  • vitamin E
  • pantothenic acid
  • thiamine
  • riboflavin
  • folacin in relatively large quantities
  • potassium
  • iron

Slightly less, but also present in mushrooms:

  • manganese
  • cobalt
  • rubidium
  • nickel

The principle of rational nutrition

Biologically active substances are divided into endogenous and exogenous. The former are produced in the body, and the latter enter the gastrointestinal tract with food. Ecdogenic include high molecular weight biopolymers and low molecular weight regulators. But we get carbohydrates, fats, proteins and vitamins from food products. They are needed to provide energy. And energy is needed even for a state of rest, not to mention physical activity. Plastic functions also “fall on the shoulders” of exogenous substances.

According to experts from the Institute of Nutrition, we should receive per day more than 600 substances, of which twenty are amino acids, and 17 are vitamins. There must be a certain ratio between the two types of substances that we get from food and that are synthesized in the body. Otherwise, the functioning of the body will be impaired. This is why you need a balanced diet.

You need to eat right to get sick less and live longer. Nutrient sources are interchangeable. For example, the Japanese use more fish than meat, that’s where they get animal proteins. A lack of calories and proteins (for example, among vegetarians) significantly weakens the immune system.

Watch your diet and be healthy!

The diet, along with proteins, fats, and carbohydrates, must contain vitamins and mineral salts, which are used in active enzyme complexes and ensure the maintenance of the active properties of biological membranes.

These nutrients make up the group essential, i.e. those that are practically not produced by the body and must come from external environment with food. A deficiency of essential substances in the body leads to severe tissue and functional changes, accompanied by a significant decrease in physical activity and immunity, as well as a deterioration in mental health.

Vitamins– (from lat. vita– life) biologically active substances of various chemical natures, partially synthesized by the body or supplied with food. Their action is expressed mainly in strengthening and regulating vital functions. Currently, about 50 vitamins are known that perform various roles in the body, but in general are regulators of metabolic processes. The most important vitamins are presented in table. 2.

Table 2

The most important vitamins

Vitamin Physiological action and hypovitaminosis Sources (food Daily norm
A Affects vision, growth and development of the body. Participates in the formation of visual pigment. With vitamin deficiency, twilight vision is impaired (night blindness), damage to the cornea of ​​the eyes, dryness of the epithelium and its keratinization Animal fats, meat, liver, eggs, milk. Sources of carotene, from which vitamin A is formed, are carrots, apricots, nettles. 1.5 g
D Regulates the exchange of calcium and phosphorus. If there is a deficiency in childhood, rickets develops (the process of bone formation is disrupted) Fish fat, egg yolk, liver. Formed in the skin under the influence of ultraviolet rays 2.5 g
E It has an antioxidant (antioxidant) effect on intracellular lipids. With a deficiency, skeletal muscle dystrophy develops and sexual function is weakened. Vegetable oil, salad 10–15 g
TO Participates in the synthesis of prothrombin, promotes normal blood clotting. With a deficiency, blood clotting decreases Spinach, lettuce, cabbage, tomatoes, carrots. Synthesized by intestinal microflora 0.2–0.3 mg
IN 1 Participates in the metabolism of carbohydrates, fats, proteins, and in the conduction of nerve impulses. If there is a deficiency - disorder motor activity, paralysis, disruption gastrointestinal tract Cereals and legumes, liver, chicken yolk 1.5–2 mg

End of table. 2

AT 2 Participates in cellular respiration. If there is a deficiency - clouding of the lens, damage to the oral mucosa Brewer's yeast, liver, raw eggs, grains and legumes, tomatoes 2–3 mg
RR Participates in cellular respiration, normalizes the functions of the gastrointestinal tract and liver. With a deficiency, pellagra develops (skin inflammation, diarrhea, dementia) Yeast, bran, wheat, rice, barley, peanuts. Can be synthesized from tryptophan (an essential amino acid not synthesized in the human body, an integral part of many proteins) 15 mg
AT 6 Protein metabolism and the synthesis of enzymes that ensure the exchange of amino acids affect hematopoiesis. If there is a deficiency - skin disease, anemia, convulsions Liver, kidneys, chicken yolk, grains and legumes, bananas. Synthesized by intestinal microflora 1.5–3 mg
AT 12 Participates in the synthesis of RNA (ribonucleic acid), provides the hematopoietic function of the body. If there is a deficiency - anemia Liver, kidneys, meat. Synthesized by intestinal microflora 2 mcg
WITH Participates in redox processes. Increases resistance to infections. With a deficiency - scurvy (damage to the walls of blood vessels, the development of small hemorrhages in the skin, bleeding gums) Rosehip, pine needles, immature walnuts, green onions, black currants, potatoes, cabbage, oranges 50–199 mg

The lack of vitamins in food leads to diseases called vitamin deficiencies (scurvy, polyneuritis, etc.), their deficiency leads to a weakening of the body or hypovitaminosis. Excess vitamin can also be harmful and lead to a disease called hypervitaminosis. Vitamins are divided into water-soluble (vitamins B, C, P, PP) and fat-soluble (A, D, E, K).

Maintaining health is only possible with sufficient varied diet, containing a complex of all vitamins.

Optimal content is important minerals in basic nutrition. Minerals help build bone tissue in the body, which mainly includes calcium salts, phosphoric acid; participate in the synthesis of a number of important organic compounds (proteins, phosphorites, etc.); contribute to the formation of digestive juices, the synthesis of hormones, maintaining a certain osmotic pressure of the blood, etc.

Distinguish macronutrients, found in the product in relatively large quantities (on the order of tenths and hundredths of a percent by weight of the product), and microelements.

Macroelements include phosphorus, potassium, sodium, magnesium, calcium, iron, sulfur, chlorine, silicon. Microelements are contained in the product in negligibly small doses. This aluminum, barium, boron, bromine, iodine, cobalt, manganese, tin, selenium, etc.

Of the macronutrients in food, the most important are phosphorus, calcium, iron, magnesium, sodium, and chlorine. Every day a person should receive 2–3 g of potassium, 1800–2000 mg of phosphorus, 800–1100 mg of calcium, 15–17 mg of iron, 300–500 mg of magnesium. The significance of the actual elements in products is determined by their characteristics. Phosphorus participates in the functioning of the brain. Iron Helps red blood cells deliver oxygen to different parts of the body. Magnesium ensures bone strength and the functioning of the cardiac, nervous and muscular systems. Promotes energy production and participates in protein synthesis. Calcium supports the structure of bones and teeth.

The acid-base balance in the body is determined by the content of acidic and alkaline mineral elements in tissue and cellular fluids. Sources of acid radicals (P, S, Cl) - meat, fish, eggs, lard, grain products, alkaline bases (Ca, Mg, Na, K) - milk, dairy products, vegetables and fruits.

Microelements are also extremely important in nutrition. Determined that copper Helps iron perform its function in the production of hemoglobin in the blood, maintains skin elasticity and hair health. Together with cobalt participates in the processes of blood formation; manganese and fluorine in turn participate in the formation of bones and teeth; iodine necessary for the normal functioning of the thyroid gland and its production of the hormone thyroxine, participates in the regulation of growth, development and metabolism. Selenium powerful antioxidant. Together with vitamin E, it protects the body from free radicals. Zinc improves metabolism and strengthens the immune system. Helps heal problem skin and heal wounds.

The absence of microelements in food products causes endemic diseases associated with disruption of the synthesis of enzymes and hormones and weakening of the metabolic processes they catalyze.

Currently, the following norms for the need of microelements have been established: zinc - 5-10 mg, copper - 2, fluorine - 1, iodine - 0.2, manganese - 5-10, chromium - 5-10, cobalt - 0.1-0, 2, molybdenum – 0.5 g, selenium – 0.5 mg.

Microelements are found in many foods of plant and animal origin. They are rich in bread, cereals, vegetables, and fruits. There is especially a lot of iodine in seafood products. Microelements in doses exceeding their natural content in food products - strong poisons. Copper, lead, mercury, arsenic, and tin are especially poisonous.

Water

Water is found in some amount in all food products. It is of paramount importance for the life and existence of living organisms, as it is part of the blood, lymph, muscles, connective and other tissues. Water is the medium for the body’s biochemical processes.

A decrease in the amount of water in the human body leads to thickening of the blood, increasing its viscosity, which complicates the work of the heart and impairs critical processes exchange.

The average water requirement is 2.5–3 liters per day. The body receives this amount due to drinking water– 1.4–1.5 l; water in solid products – 0.5–0.7 and that formed as a result of metabolism – 0.3–0.4 l.

The increased need for water cannot be compensated by frequent and abundant drinking. To reduce thirst, you need to drink in small sips, retaining the water in your mouth. Water at a temperature of 7–12º, especially alkaline, quenches thirst better. During the day, you should drink liquid in small portions, since its abundant consumption leads to overload of the body, increases sweating, complicates the work of the heart, and reduces performance.

Drinking regime affects digestion, water stimulates gastric secretion. However, its excess consumption reduces the concentration of digestive juices.

Basic principles of rational

and balanced nutrition

Since nutrition is a necessary physiological condition for the normal functioning of the body, when compiling diets (daily portions of food), it is important to maintain the correct ratios between the main nutrients, taking into account the relationship metabolic processes and correspondence of food calorie content to actual energy expenditure. These are the basic principles of rational and balanced nutrition.

It is necessary to supply the body with an amount of energy corresponding to its consumption during physical activity. Currently, this principle is often violated. Due to excessive consumption of energy-intensive foods (bread, potatoes, animal fats, sugar, etc.), the energy value of daily rations exceeds the body’s energy consumption. With age there is an accumulation overweight body and the development of obesity, which accelerates the onset of many chronic degenerative diseases.

The energy value of food depends on the proteins, fats, and carbohydrates it contains. To determine the amount of energy received or given off by a body in the process of heat exchange, the concept is used calorie– a unit of heat equal to 4.18 J. At the same time, the energy value of 1 g of proteins, fats and carbohydrates, taking into account their digestibility, is 4, 9 and 4 kcal, respectively.

The energy received from food is spent on maintaining the vital functions of the body, including metabolism and physical activity. The amount of energy released when the body absorbs a particular food product is called calorie content.

Energy and nutrient requirements are differentiated depending on gender, age, and degree of physical activity. For example, intense physical labor requires additional energy to enter the body. Its daily consumption in men during heavy physical activity increases by more than 40%, the need for proteins (by 30%), fats (by 63.5%), and other food ingredients increases. The need for food in women is lower than in men, which is due to the lower intensity of metabolic processes in their bodies.

Compliance with the principles of a balanced diet, taking into account age, gender, and degree of physical activity, provides for a differentiated distribution of calories in the diet between proteins, fats, carbohydrates, as well as their adequate ratio with vitamins and minerals. Every day, about 70 ingredients must be supplied to the body in a certain quantity, many of which are irreplaceable and therefore vital.

Thus, the ratio between proteins, fats, and carbohydrates is normally taken to be 1: 1: 4 for young men and women engaged in mental work, and 1: 1.3: 5 for heavy physical labor. When calculating, the number of proteins is taken as 1. For example, if the diet contains 90 g of protein, 81 g of fat and 450 g of carbohydrates, then the ratio will be 1: 0.9: 5. In the diet of healthy young people living in temperate climate and not engaged in physical labor, proteins should be 13, fats - 33, carbohydrates - 54% of the daily energy value of the diet, taken as 100%.

When assessing protein balance, it is taken into account that animal proteins should account for 55% total number proteins. Of the total fat in the diet vegetable oils as a source of essential fatty acids should be up to 30%. The balance of carbohydrates should be as follows: starch 75–80, easily digestible carbohydrates – 15–20, fiber and pectins – 5% of the total amount of carbohydrates. The best ratio for absorption: Ca: P: Mg – 1: 1.5: 0.5.

It is most advisable to eat 3 or 4 meals a day. The following distribution of calorie intake is recommended: 4 meals a day: breakfast 35–40, lunch 30–35, afternoon snack 5, dinner 25–30%; 3 meals a day – 40, 35 and 25%, respectively. In this case, the intervals between meals should not exceed 4–5 hours. This eliminates the feeling of hunger and ensures better digestion and absorption of food. A specific time for eating should be established and strictly adhered to.

The weight of the daily diet should be 2.3–3 kg. For dinner, it is not recommended to eat foods that linger in the stomach for a long time and are highly stimulating. nervous system and secretory activity of the digestive organs (ham, fatty meat, cocoa, coffee, etc.). Dinner should be no later than 2 hours before bedtime, otherwise the digestibility of food decreases, which entails bad dream and decreased mental performance the next day.

High organoleptic properties of food ( appearance, consistency, taste, smell, color, temperature) promote the secretion of saliva and gastric juice even before food enters the digestive tract, and have a beneficial effect on digestion.

Compliance with these principles of rational and balanced nutrition makes it complete, which increases the body’s resistance to harmful influences environment and reduces the incidence of a number of non-communicable chronic diseases in the population.

South Kazakhstan State Pharmaceutical Academy

Department of Biochemistry, Biology and Microbiology

ABSTRACT

ON THE TOPIC: “Biochemical foundations of a balanced diet. Common pathways of nutrient catabolism. Biological significance organic and mineral components of human food"

Prepared by: Aubakirova A

Group: 307 B-FR

Accepted: Mambetkulova K.K.

Shymkent - 2014

Plan

I. Introduction. Biochemistry of nutrition.

II. Biochemical basis of balanced nutrition.

Ø Biochemical basis of human nutrition.

Ø Energy sources.

Ø Essential substances of the body.

III. General characteristics of metabolism.

Ø Two sides (phases) of metabolism.

Ø Stages of nutrient catabolism.

IV. Conclusion.

V. List of used literature.

I. Introduction. Biochemistry of nutrition.

Human food contains many chemical compounds, both organic and mineral. The main share of organic food substances consists of carbohydrates, fats, proteins - the main nutrients. Some organic substances are minor nutrients required in small quantities; These include, in particular, vitamins.

The main nutrients are mostly polymers. In the gastrointestinal tract, they are hydrolyzed with the participation of hydrolase enzymes into monomers: this is the essence of digestion. During the digestion process, a decrease in the diversity of substances occurs: from countless proteins of different structures, polysaccharides, fats, 20 different amino acids are obtained, a small number of monosaccharides (mainly glucose, fructose, galactose), glycerol, fatty acids (mainly oleic, stearic, palmitic). Monomers, as low-molecular substances, penetrate much more easily through the cell membranes of the intestinal epithelium (polymers are practically not absorbed). Monomers are transported with the blood to all organs and tissues and are used by cells.

Nutrients can be replaceable or irreplaceable. Replaceable ones are those that can be formed in the body from other substances. For example, human cells can synthesize any monosaccharide they need from amino acids, fats can be formed from carbohydrates, some amino acids are formed from other amino acids or from carbohydrates.

Essential nutrients are not synthesized from other substances and therefore must be contained in food in finished form. Essential minerals include all mineral components, as well as vitamins, some amino acids and some fatty acids.

II. Biochemical basis of balanced nutrition.

1. Biochemical basis of human nutrition.

A complete diet should contain:

1) energy sources (carbohydrates, fats, proteins);

2) essential amino acids;

3) essential fatty acids;

4) vitamins;

5) inorganic (mineral) acids);

6) fiber;

2. Energy sources.

Carbohydrates, fats and proteins are macronutrients. Their consumption depends on the height, age and gender of a person and is determined in grams.

Carbohydrates constitute the main source of energy in human nutrition - the cheapest food. IN developed countries about 40% of carbohydrate intake comes from refined sugars, and 60% comes from starch. In less developed countries, the proportion of starch is increasing. Carbohydrates provide the bulk of energy in the human body.

Fats- This is one of the main sources of energy. They are digested in the gastrointestinal tract (GIT) much more slowly than carbohydrates, therefore they better contribute to a feeling of satiety. Triglycerides of plant origin are not only a source of energy, but also essential fatty acids: linoleic and linolenic.

Squirrels- the energy function is not the main one for them. Proteins are sources of essential and non-essential amino acids, as well as precursors of biologically active substances in the body. However, the oxidation of amino acids produces energy. Although it is small, it makes up some part of the energy diet.

Can ethyl alcohol serve as a source of energy? The oxidation of 1 g of ethanol releases 7 kcal of energy. This is more than the breakdown of 1 g of carbohydrates, and less than the breakdown of 1 g of fat. The energy released during the oxidation of ethanol is stored in the form of ATP. Ethanol metabolism occurs in the liver.

This reaction takes place in the cytoplasm. Then acetaldehyde undergoes re-oxidation, but in the mitochondria.

When ethanol is oxidized to acetic acid, NADH2 is released, which goes to the tissue respiration chain and ATP is formed.

Acetic acid is further activated. Ac-CoA enters the TCA.

But ethanol is not a good enough source of energy.

The reasons for this are as follows.

1. The resulting acetaldehyde and ethyl alcohol itself are toxic to humans, especially to cell membranes.

2. Patients with alcoholism consume little adequate food (low protein).

3. Strong alcoholic drinks do not contain vitamins and minerals. Therefore, vitamin deficiencies are common - most often vitamin B1 deficiency: alcoholic polyneuritis - Wernicke-Korsakoff syndrome (neurological disorders).

4. A lot of NAD is needed to oxidize ethanol and acetaldehyde. Therefore, the supply of NAD in the cell, which is necessary for the oxidation of natural foods, decreases. First of all, protein and fat metabolism suffer.

5. In the body, ethanol can only be converted into fats and steroids, but glucose and glycogen cannot be synthesized from it. And neurons in the human brain consume only glucose. Therefore, the function of the central nervous system is impaired.

6. Alcoholics have excessive formation of ketone bodies, so their breath smells similar to the smell that occurs in patients with diabetes.

7. The synthesis of ketone bodies is enhanced.

In many developed countries, people now suffer from excess nutrition, which leads to obesity, and in underdeveloped countries, on the contrary, from malnutrition.

Malnutrition 12 thousand people in the world die of hunger every day. Malnutrition in children leads to disorders such as wasting and kwashiorkor.

Kwashiorkor develops in children when they eat low-calorie foods with insufficient protein content. The child's growth slows down, edema and degenerative changes in the liver, kidneys, and pancreas develop. Even if such a child does not die, prolonged protein starvation still makes him disabled for life. In adults, with prolonged protein starvation, similar phenomena develop.

3. Essential substances of the body.

1. Vitamins.

2. Amino acids.

3. Polyunsaturated fatty acids.

4. Inorganic substances(mineral elements).

5. Fiber.

Vitamins - the most important group of essential nutritional factors. Concentration of vitamins in tissues and daily requirement they are small, but with insufficient intake of vitamins into the body, characteristic and dangerous pathological changes occur.

Vitamins were discovered during the study of diseases such as beriberi, scurvy and others, which are now known to occur due to vitamin deficiency. In the words of Academician V.A. Engelhardt, “vitamins revealed themselves not by their presence in the body, but by their absence.”

Vitamins contribute to:

Maintaining the body's defenses,

Increases its resistance to various environmental factors,

Helps adapt to deteriorating environmental conditions

They play a vital role in maintaining immunity, i.e. do our body

more resistant to diseases.

Vitamins are not an energy supplier for the body. However, they regulate our metabolism and keep us in good shape.

The concentration of vitamins in tissues and the daily need for them are small, but with insufficient intake of vitamins into the body, characteristic and dangerous pathological changes occur.

Two conditions are associated with a violation of the supply of vitamins to the body: a lack of vitamin - hypovitaminosis (avitaminosis) and an excess of vitamin - hypervitaminosis.

Essential amino acids - these are amino acids that are not synthesized in the body, but must come from outside: Tryptophan (daily requirement 0.5 g per day), threonine, isoleucine, lysine, valine, leucine (daily requirement about 2 g), phenylalanine (daily requirement .about 2 g), methionine (daily consumption about 2 g). arginine is essential only in children.

Food proteins vary greatly in amino acid composition. Plant proteins contain an incomplete set of amino acids and in ratios unusual for our body.

Animal proteins have good chemical characteristics and high biological value. The body digests animal proteins well and effectively uses the resulting amino acids.

Plant-based proteins are low chemical value. The proteins of any one plant may be missing one or more amino acids. Therefore, the body must receive a variety of plant foods. The proteins of cereal grains are not completely digested, since they are protected by a shell consisting of cellulose, which is not broken down by digestive enzymes of the gastrointestinal tract.

Essential fatty acids. These include linoleic and linolenic acids. They are not synthesized in the human body and therefore must be supplied with food. Usually we do not lack them, since they are contained in plant products(oils), as well as in fish and chicken fats.

In the body, essential fatty acids are part of cell membranes and are also precursors for the synthesis of biologically active substances, such as prostaglandins. Linoleic and linolenic acids are direct precursors of arachidonic acid. It is from arachidonic acid that prostaglandins, thromboxanes and leukotrienes are synthesized.

Prostaglandins are 20-carbon fatty acids containing a five-membered hydrocarbon ring. There are several groups of prostaglandins, which differ from each other in the presence of ketone and hydroxyl groups in the 9th and 11th positions.

Prostaglandin precursors are released from membrane phospholipids (non-food!) and are broken down by the enzyme phospholipase-A2. This is a regulatory step in the biosynthesis of prostaglandins. This step controls the amount of substrate that is exposed to the subsequent action of the cyclooxygenase enzyme.

Corticosteroids inhibit prostaglandin synthesis by inhibiting the enzyme phospholipase-A2. This may explain the anti-inflammatory effect of corticosteroids.

The synthesis of prostaglandins occurs in 2 stages.

The 1st stage is catalyzed by PG-N-cyclooxygenase. This enzyme works according to a universal mechanism and, regardless of which organ or tissue this reaction occurs in, it ends with the formation of PGN2. This is a complex multienzyme complex that is localized in microsomes. It catalyzes the formation of the cyclopentane ring.

Acetylsalicylic acid (aspirin), as well as all anti-inflammatory non-steroidal drugs, suppress the synthesis of prostaglandins, being inhibitors of this enzyme.

The 2nd stage is catalyzed by enzymes, the general name of which is convertases. These enzymes have tissue specificity, so in each type of tissue a different product is formed from PGN2:

1) in the brain - PGD;

2) in the gonads - PGE, PGF.

Prostaglandins act in the cells where they are synthesized. The nature of the action of prostaglandin depends on the type of cell. This is the fundamental difference between prostaglandins and hormones.

Physiological effects of prostaglandins:

1) prostaglandins enhance inflammatory processes;

2) regulate blood flow to a specific organ;

3) simulate synaptic transmission.

PGE causes relaxation of the muscles of the bronchi and trachea. PGE1 and PGE2 are used as means to relieve bronchospasm (aerosol preparations). The clinic uses prostaglandin inhibitor drugs.

Labile products of prostaglandin conversion are thromboxanes. Their function is that they participate in the regulation of platelet activity. Being powerful stimulators of blood clots, they promote platelet aggregation.

Prostacyclins prevent platelet aggregation.

Leukotrienes- These are derivatives of arachidonic acid. Participate in immune processes, inflammatory and allergic reactions, have an antispasmodic effect, affect arterial pressure and vascular permeability.

Inorganic substances (minerals) are inorganic components of food.

Currently, about 70 are found in our body various elements, excluding elements of the transuranium series.

Elements found in the body are divided into:

a) macroelements - their content is grams, tens or hundreds of grams. These are Na, K, Ca, P, S, Cl.

b) microelements, their content in the body is calculated in milligrams and tens of milligrams. These are Fe, Cu, Zn, Mo, Co, F, I, Br and some others.

Mineral elements can also be classified according to their necessity for the functioning of the body.

Those elements that are absolutely necessary for the body and perform specific functions in it are called bioelements.

Those elements whose functions in the body are unknown are designated as incidental impurities. An example of a random impurity is gold (Au).

Minerals in the body are distributed very unevenly. The hardest tissue in our body is tooth tissue, it contains 98% minerals, and the extracellular fluid contains only 0.5-1% minerals. Fluoride is most abundant in tooth enamel, iodine is found in the thyroid gland, and iron is found in red bone marrow. Most mineral elements are concentrated in individual tissues.

Evenly distributed: Mg, Al, Br, Se.

Cellulose -component of non-recyclable dietary fiber. Fiber contains cellulose, hemicellulose, lignin, and pectin. These substances are found in fruits, vegetables, and unprocessed grains. Not digested in the gastrointestinal tract.

The importance of fiber for nutrition of the body is as follows.

1. Regulates intestinal motility.

2. Participates in the formation of feces.

3. Promotes the development of a feeling of fullness when eating.

4. Creates the necessary conditions for the functioning of normal intestinal microflora.

5. Stimulates the excretion of cholesterol with bile.

6. Reduces and delays glucose absorption (important for patients with diabetes mellitus).

7. Is a sorbent for toxic substances.

> Vitamins are the most important class of essential nutrients. The main causes of hypo- and avitaminosis

Nutrients or Nutrients- these are chemicals - components of food products that the body uses to build, renew and repair its organs and tissues, as well as to obtain energy from them to perform work.

There are two groups of nutrients. One group includes the main nutrients, or macronutrients (from the Greek macro - large). Another group of nutrients is called micronutrients (from the Greek micros - small), which includes vitamins and minerals.

Macronutrients, or essential nutrients- proteins, fats and carbohydrates - are needed by a person in quantities measured in several tens of grams. They are called essential nutrients because, when oxidized, they provide energy to perform all body functions.

Micronutrients- vitamins and minerals are needed by humans in very small quantities - in milligrams or micrograms. They are not sources of energy, but are involved in the absorption of food energy, in the regulation of functions, in the implementation of the processes of growth and development of the body.

Among the nutrients there are those that are not formed in the human body. These nutrients are called essential or essential. They must come with food. The absence of any of them in the diet leads to illness, and with prolonged deficiency - to death.

Other nutrients can be formed in the human body from essential nutrients. That's why they are called replaceable, i.e. they can be replaced by having an abundance of essential nutrients. However, non-essential nutrients must also be supplied with food in certain quantities, as they serve as sources of energy.

Currently, nutritional science knows about 50 essential nutrients that cannot be formed in the body and their only source is food (see Table 1).

All nutrients are divided into 6 main groups - carbohydrates, proteins, fats, vitamins, minerals and water. In addition, food contains a large number of other biologically active substances that are important for maintaining health and preventing many chronic diseases. These include many chemical components found primarily in plant products, collectively called phytocompounds, of which representatives of the flavonoid class are the most studied. Their role in maintaining human health emphasizes the importance of plant foods in the diet.

Consumption of a certain amount and in certain proportions of essential nutrients is one of the scientific principles of rational and healthy eating.

However, in the process of nutrition, a person deals not with nutrients, but with food products. The supply of nutrients to required quantities and ratios is carried out through the consumption of a diverse set of foods. Therefore, the principles and rules of healthy eating should be expressed in the rules and principles of consumption various types food.

Table 1 - Essential nutrients that must be supplied with food

Carbohydrates

Minerals

Vitamins

Fat soluble

Fatty acid

linoleic

Amino acids

Isoleucine

Water soluble

Methionine

Phenylalanine

Tryptophan

Manganese

Histidine

Molybdenum

Pantothenic acid

The main causes of hypo- and avitaminosis

These diseases are called differently vitamin deficiency diseases. They develop when there is a lack of one or more vitamins in the body.

Currently, cases of vitamin deficiency ( complete absence any vitamin) are extremely rare, but shortages of these valuable substances are quite common.

Vitamins are important for the body, irreplaceable biologically active substances that take part in chemical reactions occurring inside our body. Vitamins are part of many enzymes, substances that direct the course of chemical reactions along a certain path and increase their speed.

Development risk factors.

* Increased or decreased ambient temperature.

* Prolonged physical or psycho-emotional stress.

* Diseases of the endocrine glands.

* Some physiological states of the body (pregnancy, lactation, when the child’s need for vitamins must also be met).

* Occupational hazards, etc.

* Diseases of the gastrointestinal tract, which reduce the absorption of vitamins in the intestines.

A lack of vitamins in the body can be associated with their insufficient intake from food (primary hypovitaminosis), as well as with a violation of their absorption in the intestines or the body’s excessive need for them (secondary hypovitaminosis, for example, with large physical activity, during treatment with antibiotics).

It is important good nutrition. It has long been noted that a monotonous diet (canned food, dry foods, flour products) leads to hypopolyvitaminosis (lack of several vitamins in the body). Such conditions are observed in regions of natural or social disasters (wars, crop failures, etc.).

Symptoms . With a lack of vitamins, many metabolic processes in the body are disrupted. This leads to deterioration general well-being, decreased performance and the body’s resistance to infections. Vitamin deficiency is especially dangerous for the growing body of a child or teenager, whose metabolic rate is especially high. Unfortunately, even a well-balanced diet does not always provide the body with enough vitamins. Therefore, in some cases it is necessary to take ready-made vitamin complexes.

Symptoms of the disease increase gradually as the body uses up reserves of a particular vitamin in various organs. The following stages of vitamin deficiency diseases are distinguished.

Stage I - hypovitaminosis. During this period there are no clear manifestations of the disease. Come to the fore general symptoms disruption of normal operation internal organs: weakness, fatigue, low performance.

Stage II - hypovitaminosis. Vitamin deficiency increases, and obvious symptoms of the disease appear, which are directly related to the deficiency of one or another vitamin. This can be detected using special laboratory tests.

Stage III - vitamin deficiency. This is an extreme degree of deficiency of a vitamin (vitamins) against the background of its absence in the body. This stage is characterized by vivid symptoms that do not allow the clinical picture of the disease to be confused. Laboratory tests determine a significant decrease in the amount of vitamin.

Vitamin A deficiency

It develops when there is a reduced amount of vitamin A and carotene in food, a violation of its absorption in the intestines, as well as a violation of the synthesis of vitamin A from carotene in the body.

Vitamin A is found in the following animal products: yolk, liver, especially sea ​​fish, butter. Carotene is found in vegetables and fruits that are orange and red in color. When it enters the body, vitamin A is synthesized from it, which is necessary for the normal course of biochemical processes. Vitamin A is fat soluble.

Its daily requirement is 1.5 mg. It is necessary for the functioning of the epithelium of the skin and mucous membranes, sebaceous and lacrimal glands, as well as for the formation of visual pigment.

Vitamin B1 (thiamine) deficiency

It is more common in Asian countries, where a diet consuming large amounts of polished rice predominates. Another cause of hypovitaminosis B1 may be a violation of the absorption of this vitamin in the intestine, which occurs in some pathological conditions (diarrhea, vomiting, severe intestinal diseases).

Risk factors: some physiological conditions (pregnancy, lactation), heavy physical activity, diabetes mellitus, feverish conditions, thyrotoxicosis.

Vitamin B2 (riboflavin) deficiency

Occurs when there is insufficient intake of vitamin B2 from food, when its absorption in the intestines is impaired, as well as when its destruction is increased.

Nicotinic acid deficiency

Risk factors: insufficient dietary intake (with a monotonous diet, for example, with the predominant consumption of corn), impaired absorption of the vitamin in the intestines (diseases small intestine with malabsorption), some conditions of the body characterized by an increased need for the vitamin (physical activity, pregnancy, etc.).

Vitamin B6 (pyridoxine) deficiency

In adults, deficiency of this vitamin develops only when its synthesis in the intestines is disrupted. This is possible during treatment with antibiotics (which leads to inhibition of the microflora responsible for vitamin synthesis), significant physical activity, or with an increased need for the vitamin (pregnancy, lactation, etc.).

Vitamin B6 is found in large quantities in animal products and yeast.

Vitamin C (ascorbic acid) deficiency

This vitamin is directly involved in redox processes, ensures optimal vascular permeability, and regulates collagen synthesis.

Vitamin D deficiency

Most of the vitamin D found in the body is produced in the skin under the influence of ultraviolet rays. A smaller part enters the body with food.

The most important are vitamins D2 and D3.

This vitamin is found in large quantities in fat-containing foods of animal origin: butter, milk, egg yolk, cod liver and other sea fish.

Risk factors for hypovitaminosis D:

* insufficient sun exposure;

* prematurity of the child;

* some infectious diseases with a shift in the acid-base balance of the body.

Vitamin K deficiency

Vitamin K is mostly absorbed in the intestines. Some of it is synthesized by the microflora of the small intestine.

More common in childhood. The most common cause of hypovitaminosis K is chronic intestinal diseases, obstruction (compression) of the bile ducts, which leads to disruption of the flow of bile into the small intestine.

Violation of vitamin K absorption is also possible with an overdose of dicoumarin.