The importance of proteins for baby food. The physiological role of protein Proteins and their physiological significance

Lecture #3

Topic: The physiological significance of proteins and amino acids in human nutrition.

1 The most important groups of peptides and their physiological role.

2 Characteristics of proteins of food raw materials.

3 New forms of protein food.

4 Functional properties of proteins.

1 The most important groups of peptides and their physiological role.

Peptides are oligomers composed of amino acid residues. They have a low molecular weight (the content of amino acid residues ranges from a few pieces to several hundred).

In the body, peptides are formed either in the process of synthesis from amino acids, or during the hydrolysis (cleavage) of protein molecules.

To date, the physiological significance and functional role of the most common groups of peptides, on which human health, organoleptic and sanitary-hygienic properties of food products depend, have been established.

buffer peptides. In the muscles of animals and humans, dipeptides have been found that perform buffer functions, that is, maintain a constant pH level.

Peptides-hormones. Hormones - substances of an organic nature produced by gland cells regulate the activity of individual organs, glands and the body as a whole: contraction of the smooth muscles of the body and secretion of milk by the mammary glands, regulation of the activity of the thyroid gland, growth activity of the body, the formation of pigments that determine the color of the eyes, skin, hair .

Neuropeptides. These are two groups of peptides ( endorphins And enkephalins ) contained in the brain of humans and animals. They determine the reactions of behavior (fear, fear), affect the processes of memorization, learning, regulate sleep, and relieve pain.

Vasoactive peptides synthesized from food proteins as a result, they affect vascular tone.

Peptide toxins are a group of toxins produced by organisms, poisonous mushrooms, bees, snakes, sea mollusks and scorpions. They are undesirable for the food industry. The greatest danger is the toxins of microorganisms (Staphylococcus aureus, botulism bacteria, salmonella), including fungi that develop in raw materials, semi-finished products and finished foods.

Antibiotic peptides. Representatives of this group of peptides of bacterial or fungal origin are used in the fight against infectious diseases caused by streptococci, pneumococci, staphylococci and other microorganisms.

Taste peptides- First of all, these are compounds with a sweet or bitter taste. Bitter taste peptides are formed in young, unripe fermented cheeses. Sweet tasting peptides ( aspartame ) are used as a sugar substitute.

Protective peptides perform protective functions, primarily antioxidant.

2 Characteristics of proteins of food raw materials.

Peptides having a molecular weight of more than 5000 Da and performing one or another biological function are called proteins.

The functional properties of proteins depend on the sequence of amino acids in the polypeptide chain (the so-called primary structure), as well as on the spatial structure of the polypeptide chain (depend on the secondary, tertiary and quaternary structures).

Different food products differ in the qualitative and quantitative content of proteins.

In cereal crops the total protein content is 10÷20%. Analyzing the amino acid composition of the total proteins of various cereal crops, it should be noted that all of them, with the exception of oats, are poor in lysine (2.2÷3.8%). The proteins of wheat, sorghum, barley and rye are characterized by a relatively small amount of methionine and cysteine (1.6÷1.7 mg/100 g protein). The most balanced amino acid composition are oats, rye and rice.

In legumes (soybeans, peas, beans, vetch) the total protein content is high and amounts to 20÷40%. The most widely used is soy. Its score is close to one in five amino acids, but at the same time, soy contains insufficient tryptophan, phenylalanine and tyrosine and a very low content of methionine.

In oilseeds(sunflower, cotton, rapeseed, flax, castor oil, cariander) total protein content is 14÷37%. At the same time, the amino acid score of proteins of all oilseeds (to a lesser extent cotton) is quite high even for limiting acids. This fact determines the expediency of obtaining concentrated forms of protein from oilseed raw materials and creating new forms of protein food on their basis.

Relatively low content of nitrogenous substances in potatoes(about 2%), vegetables(1÷2%) and fruits(0.4÷1.0%) indicate an insignificant role of these types of food plant raw materials in providing food with protein.

Meat, milk and the products obtained from them contain the proteins necessary for the body, which are favorably balanced and well absorbed (at the same time, the indicator of balance and assimilation of milk is higher than that of meat). The protein content in meat products ranges from 11 to 22%. The content of proteins in milk ranges from 2.9 to 3.5%.

3 New forms of protein food.

Today, in a constantly growing society and limited resources, a person faces the need to create modern food products that have functional properties and meet the requirements of the science of healthy nutrition.

New forms of protein food are food products obtained on the basis of various protein fractions of food raw materials using scientifically based processing methods, and having a certain chemical composition, structure and properties.

Various vegetable protein sources are widely recognized: legumes, bread and cereals and by-products of their processing, oilseeds; vegetables and gourds, vegetative mass of plants.

At the same time, soy and wheat are mainly used for the production of protein products.

Soy protein processing products are divided into three groups, differing in protein content: flour and cereals are obtained by grinding; they contain 40÷45% protein of the total mass of the product; soy concentrates are obtained by removing water-soluble components, they contain 65÷70% protein; Soy isolates are obtained by protein extraction and contain at least 90% protein.

Based on soy textured protein products in which soy proteins are used, for example, instead of meat proteins. Hydrolyzed soy proteins are called modified. They are used as functional and flavoring food additives.

Today, soy milk, soy sauce, tofu (bean curd) and other food products are also produced on the basis of soy.

Dry wheat gluten with a protein content of 75÷80% is obtained from wheat or wheat flour by water extraction.

At the same time, the presence of limiting amino acids in vegetable proteins determines their inferiority. The way out here is the joint use of different proteins, which provides the effect of mutual enrichment. If, at the same time, an increase in the amino acid score of each essential limiting amino acid is achieved in comparison with the separate use of the original proteins, then one speaks of simple enrichment effect, if after mixing the amino acid score of each amino acid exceeds 1.0, then this is true enrichment effect. The use of such balanced protein complexes provides an increase in the digestibility of vegetable proteins up to 80÷100%.

4 Functional properties of proteins.

Proteins and protein concentrates are widely used in food production due to their unique functional properties, which are understood as physicochemical characteristics that determine the behavior of proteins during processing into food products and provide a certain structure, technological and consumer properties of the finished product.

The most important functional properties of proteins include solubility, water-binding and fat-binding ability, the ability to stabilize dispersed systems (emulsions, foams, suspensions), and form gels.

Solubility- This is the primary indicator for evaluating the functional properties of proteins, characterized by the amount of protein passing into solution. Solubility is most dependent on the presence of non-covalent interactions: hydrophobic, electrostatic and hydrogen bonds. Proteins with high hydrophobicity interact well with lipids, with high hydrophilicity interact well with water. Since proteins of the same type have the same charge sign, they repel each other, which contributes to their solubility. Accordingly, in the isoelectric state, when the total charge of the protein molecule is zero and the degree of dissociation is minimal, the protein has low solubility and can even coagulate.

Water-binding the ability is characterized by water adsorption with the participation of hydrophilic amino acid residues, fat-binding adsorption of fat due to hydrophobic residues. On average, for 1 g of protein, it can bind and hold on its surface 2–4 g of water or fat.

Fat emulsifying And foaming The ability of proteins is widely used in the production of fat emulsions and foams, that is, heterogeneous water-oil, water-gas systems. Due to the presence of hydrophilic and hydrophobic zones in protein molecules, they interact not only with water, but also with oil and air and, acting as a shell at the interface between two media, contribute to their distribution in each other, that is, the creation of stable systems.

Gelling agents The properties of proteins are characterized by the ability of their colloidal solution to pass from a free dispersed state into a bound-dispersed state with the formation of systems that have the properties of solids.

Visco-elastic-elastic the properties of proteins depend on their nature (globular or fibrillar), as well as the presence of functional groups by which protein molecules bind to each other or to a solvent.

Proteins, fats, carbohydrates, vitamins are the main nutrients in the human diet. Nutrients are chemical compounds or individual elements that the body needs for its biological development, for the normal course of all vital processes.

Proteins are high-molecular nitrogenous compounds, the main and indispensable part of all organisms. Protein substances are involved in all vital processes. For example, metabolism is provided by enzymes, which by their nature are related to proteins. Proteins are also contractile structures necessary to perform the contractile function of muscles - actomyosin; supporting tissues of the body - collagen of bones, cartilage, tendons; integumentary tissues of the body - skin, nails, hair.

By composition, proteins are divided into: simple - proteins (only amino acids and ammonia are formed during hydrolysis) and complex - proteins (during hydrolysis, non-protein substances are also formed - glucose, lipoids, dyes, etc.).

Among the many nutrients, proteins play the most important role. They serve as a source of essential amino acids and the so-called non-specific nitrogen necessary for protein synthesis.

The state of health, physical development, physical performance, and in young children, mental development to a large extent depend on the level of protein supply. The sufficiency of protein in the diet and its high quality make it possible to create optimal conditions for the internal environment of the body, necessary for growth, development, normal human life and its performance. Under the influence of protein deficiency, such pathological conditions as edema and fatty liver can develop; violation of the functional state of the organs of internal secretion, especially the sex glands, adrenal glands and pituitary gland; violation of conditioned reflex activity and processes of internal inhibition; decreased immunity; alimentary dystrophy. Proteins are composed of carbon, oxygen, hydrogen, phosphorus, sulfur and nitrogen, which are part of the amino acids - the main structural components of the protein. Proteins differ in the level of amino acid content and the sequence of their connection. Distinguish between animal and vegetable proteins.

Unlike fats and carbohydrates, proteins contain, in addition to carbon, hydrogen and oxygen, nitrogen - 16%. Therefore, they are called nitrogen-containing food substances. Proteins are needed by the animal organism in finished form, since it cannot synthesize them, like plants, from the inorganic substances of the soil and air. The source of protein for humans are food substances of animal and vegetable origin. Proteins are needed primarily as a plastic material, this is their main function: in general, they make up 45% of the dense residue of the body.

Proteins are also part of hormones, erythrocytes, some antibodies, having a high reactivity.

In the process of life, there is a constant aging and death of individual cellular structures, and food proteins serve as a building material for their restoration. Oxidation in the body of 1 g of protein provides 4.1 kcal of energy. This is its energetic function. Protein is of great importance for the higher nervous activity of a person. The normal content of protein in food improves the regulatory function of the cerebral cortex, increases the tone of the central nervous system.

With a lack of protein in the diet, a number of pathological changes occur: growth and development of the body slows down, weight decreases; the formation of hormones is disrupted; the reactivity and resistance of the organism to infections and intoxications decrease. The nutritional value of food proteins depends primarily on their amino acid composition and the completeness of utilization in the body. There are 22 known amino acids, each with a specific meaning. The absence or deficiency of any of them leads to a violation of individual body functions (growth, hematopoiesis, weight, protein synthesis, etc.). The following amino acids are especially valuable: lysine, histidine, tryptophan, phenylalanine, leucine, isoleucine, threonine, methionine, valine. For young children, histidine is of great importance.

Some amino acids cannot be synthesized in the body and replaced by others. They are called indispensable. Depending on the content of essential and non-essential amino acids, food proteins are divided into complete ones, the amino acid composition of which is close to the amino acid composition of human body proteins and contains all the essential amino acids in sufficient quantities, and defective ones, in which one or more essential amino acids are missing. The most complete proteins of animal origin, especially the proteins of the yolk of a chicken egg, meat and fish. Of vegetable proteins, soy proteins have a high biological value, and to a lesser extent - beans, potatoes and rice. Incomplete proteins are found in peas, bread, corn and some other plant foods.

Physiological and hygienic norms of protein requirements. These norms are based on the minimum amount of protein that is able to maintain the nitrogen balance of the human body, i.e. the amount of nitrogen introduced into the body with food proteins is equal to the amount of nitrogen excreted from it with urine per day.

The daily intake of dietary protein should fully ensure the nitrogen balance of the body while fully satisfying the energy needs of the body, ensure the integrity of body proteins, maintain high performance of the body and its resistance to adverse environmental factors. Proteins, unlike fats and carbohydrates, are not stored in the body in reserve and must be introduced daily with food in sufficient quantities.

The physiological daily norm of protein depends on age, gender and professional activity. For example, for men it is 96-132 g, for women - 82-92 g. These are the norms for residents of large cities. For residents of small towns and villages engaged in more difficult physical work, the rate of daily protein intake increases by 6 g. The intensity of muscle activity does not affect nitrogen metabolism, but it is necessary to ensure sufficient development of the muscular system for such forms of physical work and maintain its high performance.

An adult under normal conditions of life with light work requires an average of 1.3-1.4 g of protein per 1 kg of body weight per day, and during physical work - 1.5 g or more (depending on the severity of work).

In the daily diet of athletes, the amount of protein should be 15-17%, or 1.6-2.2 g per 1 kg of body weight.

Proteins of animal origin in the daily diet of adults should take 40 - 50% of the total amount of proteins consumed, athletes - 50 - 60, children - 60 - 80%. Excessive consumption of proteins is harmful to the body, as the processes of digestion and excretion of decay products (ammonia, urea) through the kidneys are hampered.

--- full-fledged

--- defective

Classification of feed by protein content. Norms of protein nutrition of animals.

The level of protein nutrition of animals is determined by the amount of digestible protein per 1 k.u., and in poultry farming - by the content of crude protein as a percentage of the dry feed mixture. For example, cows for 1 k.u. the diet requires 100-110 g of digestible protein, pigs - 100-120 g, in the feed of laying hens 16-17% of crude protein.

In order to avoid an imbalance between the breakdown of feed protein and the synthesis of bacterial protein and to prevent excessive absorption of ammonia into the blood, an optimal ratio between the soluble and insoluble protein fraction is necessary. It is desirable that cattle rations contain 40-50% of water-salt fractions in crude protein. There are many such fractions in root crops, corn silage, few in hay, haylage. In cattle, in addition, the source of protein is rumen microorganisms.

The use of synthetic nitrogen-containing substances in the feeding of dairy cattle.

The use of non-protein nitrogen supplements in ruminant feeding is of practical importance. I use urea, biuret, urea phosphate, ammonium salts of sulfuric and phosphoric acid.

Consider urea (urea): During feeding, it hydrolyzes to ammonia and CO 2 . Supplements can reduce your protein requirement by up to 25%.

For dairy cattle, the use of synthetics is important, because. it makes up for the lack of nitrogen and protein during milk synthesis.

Ways to increase the protein nutritional value of feed and diets. Preparation and use of AKD in animal husbandry.

Increasing the production of high protein feed

Rational use of high-protein feed

Use of protein substitutes in animal nutrition

Importance of fats in animal nutrition. content in feed.

In the body of an animal, lipids perform the following functions:

Included in the structure of cell membranes

Fundamentals of nervous tissue

deposit energy

Protective role

Fundamentals of hormones, vitamins

Source of essential fatty acids

Absorption, transport and storage of fat-soluble vitamins

Fats contain 2-3 times more energy than proteins and carbohydrates. Body fat content depends on age, species and body condition.

In plant foods: fat in seeds and grains. More fat in oilseeds (soybeans, flax, cotton, etc. 30-40% of dry matter). In grains of corn and oats - 5-6%. Wheat, rye - 1-2%. In the roots of tubers - 0.1-0.2%.

The source of lipids for ruminants is sunflower, cotton, cake. An effective way of feeding fats is additives in the composition of animal feed, herbal granules.

Pigs: vegetable oils have a negative effect on pork fat technology. Linseed and castor oil, marine animal fats are not recommended.

Especially high is the need for fat in newborns. The level of fat in the diet of newborns determines growth, development, and productivity. The minimum fat level for calves is 12%, lambs 15%, piglets 17%.

Physiological role of Ca. Norm. Content in feed and supplements.

Ca - 99% is in the skeleton, the mineralization of bone tissue depends on the supply of Ca and P, the availability of vitamin D. With a lack: in young people - the processes of ossification of the bone, tissue, curvature of the spine, growth retardation. In adult animals: a state of hypocalcemia, softening of the bones (osteomalacia), immobilization of Ca and P from the bones.

Ca is necessary for normal excitability of nervous tissue, muscle contractility, an important component of blood clotting.

Ca 2+ - stability of the cell membrane, adhesion of cells during tissue formation.

In highly productive cows during lactation, softening of the last tail vertebrae, curvature of the ribs, a state of hypocalcemia. In the process of milk formation, the need for Ca increases sharply. Some animals are unable to obtain the required amount through efficient use from feed, or skeletal immobilization (Ca is extracted from muscles).

Lack of Ca - muscle trembling, the body temperature of diseased cows is below 37 0 C, a state of hypocalcemia (postpartum paresis). In laying hens, softening of the bones, beak, limbs, the shell becomes thinner.

Sources of Ca:

Fish meal 30-65 g/kg

Bone meal 220 g/kg

Meat and bone meal 140 g/kg

Milk 1.3 g/kg

Green fodder 1.5 g/kg

Legumes 2.8 g/kg

The optimal ratio of Ca and P is 2:1

In the blood serum of animals, the Ca content is 10–25 mg/100 ml, and a decrease in this level to 8 mg/100 ml can be associated with pathology.

Physiological role R. Norm. Content in feed and supplements.

In animals, phosphorus is closely related to calcium. It is part of the bone tissue, is found in phosphoroproteins, nucleic acids and phospholipids. Phosphorus is needed for the formation of bone tissue, the absorption of carbohydrates and fats. Phosphorus is an indispensable component of cellular proteins, serves as an activator of a number of enzymes, and is involved in the creation of buffering in the blood and tissues. With a lack of phosphorus, signs of osteomalacia and rickets are observed. In cattle, with a lack of phosphorus, there is a perversion of appetite, animals chew the wood of feeders and other inedible materials. The lack of phosphorus in the diet causes muscle weakness, impaired fertility, has a negative impact on the productivity of cows and the growth of young animals.

The microflora of the proventriculus needs phosphorus. Phosphorus plays a special role in phosphorylation reactions that restore spent ATP.

The source of phosphorus is grain and by-products of flour milling. Bran contains 2-3 times more phosphorus than grain. The grain contains 3-4 g per 1 kg of dry matter, meal - 7.7, bran - 7-10 g. Root crops contain little phosphorus - 1.4-2 g, carrots contain 4.7 g per 1 kg of dry matter, the concentration phosphorus in skimmed water - 10 g, in fishmeal 29 g per 1 kg of dry matter.

Cu, Co, Mn, Zn value. Norms. content in feed.

Cu- together with iron and vitamin B 12, copper is necessary for the normal course of the process of hemoglobin formation, individual enzyme systems, hair growth and pigmentation, reproduction and lactation. Cu deficiency causes emaciation, depigmentation and hair loss, growth retardation, anemia, fragility and underdevelopment of the ostyak, appetite perversion and diarrhea.

co- is necessary for rumen microorganisms for the synthesis of vitamin B 12. Lack of Co leads to avitaminosis B 12 and manifests itself in weakness, exhaustion and death. Other symptoms of cobalt deficiency include loss of appetite, hair and wool eating, scaly skin, and sometimes diarrhea.

Mn- is contained in the body in small quantities, disrupts the structure of bone tissue and the function of reproduction. Calves from manganese-deficient cows often have deformed limbs, thickening of the joints, stiffness, twisting, and low growth rate. Pigs have lameness.

To compensate for the lack of manganese, manganese sulfate or potassium manganese are introduced into the diet.

In pasture grass, the content of manganese in 1 kg of dry matter is 40-200 mg, and in grass on acidic soils it can reach 500-600 mg. Rich sources of this element are rice and wheat bran.

Zn- Found in all tissues. Accumulates in greater quantities in bone tissue than in the liver. This element is necessary for normal growth, hair skin. Deficiency causes parakeratosis in calves and pigs. Deficiency symptoms: stunted growth, skin lesions in the form of redness on the abdomen.

If 1 kg of dry matter of feed contains 40-60 mg of zinc, then this meets the needs of all animals.

The physiological significance of proteins. Complete and incomplete proteins.

Protein plays a primary role in the construction of organs, tissues and vital activity of the animal organism. It is conditionally possible to distinguish 3 main functions of the protein:

Plastic - serves as a building material for the synthesis of body proteins, and is also an integral part of the products: milk, meat, eggs, wool.

Biological (regulatory) - proteins are part of many biologically active substances in the body: enzymes, hormones, immune bodies.

Energy - should not be the main one, because. the role of the main sources of energy for animals is assigned to carbohydrates and fats.

The amino acid composition of a protein can be:

--- full-fledged- have in their composition in the proper amount of essential amino acids cannot be synthesized in the body and must be obtained from food

--- defective- do not contain these amino acids or have an insufficient amount, for example, corn grain, in which crude protein is represented by a protein poor in amino acid composition - zein.

They drag, so to speak, feed of animal origin, since the concentration of amino acids in them is higher than in vegetable ones.

All people born on planet Earth cannot exist without a certain food foundation built from a number of significant substances. The pyramid or ladder of food requirements, call it whatever you like, is a kind of transport for all biological spheres. The main basis for the proper development of a living organism is proteins - transformers or carriers of useful elements.

For more than one century, biologists and geneticists have been engaged in a thorough study of natural molecules, constantly expanding the existing knowledge about their meaning, properties, structure and functions. It has long been known that proteins are complex polymeric compounds that consist of various amino acids.

This kind of chain of building "bricks" provides a person with the opportunity to interact with the outside world: eat, move, multiply, contact.

Physiological role

Our body is not able to independently synthesize “essential” amino acids (methionine, tryptophan, isoleucine, leucine, etc.), therefore it is forced to receive them from the food line.

These molecules can be called a plastic material for building billions of cells - a unit of life on the planet. A person is completely dependent on protein compounds, without them the following functions are impossible:

The catalytic or enzymatic role is responsible for the rate of biochemical reactions in every cell of the body. Enzymes, as they are also called, perform about a million important processes every second.
building function. It can be compared to the core of the globe, which consists of a protein structure. Explaining in an accessible language, these molecules are combined into collective groups, and then cooperate in internal organs, tissues and systems. They are responsible for building muscles, blood vessels, hair, tendons, take an active part in the formation of membranes and cell membranes.
structural role. Without protein complexes such as collagen, creatine and reticulin, our hair, epithelial tissue, and nail plates will not be strong and healthy.

So that the balance of significant compounds is not disturbed, it is necessary to eat rationally - include animal and vegetable ingredients in the menu, which we will talk about a little later.

The role of proteins is not limited to this. In addition, they are carriers, transporting oxygen, nutrients and trace elements to their destination (tissues, organs).

It is impossible not to mention the protective role of proteins-antibodies. Their main task is to stop a foreign agent or simply to eliminate it. Immunoglobulins will instantly react to the penetration of a pathogenic virus, microbe and bacteria.

In order for our body to recognize and “eat” all harmful microorganisms, it needs to absorb a sufficient dose of proteins. The lack of immunostimulants will affect the state of health and no artificial drugs will help. That's the way it is in physiology.

Protein deficiency - what is dangerous?

A permanent deficiency of these compounds will negatively affect the functional activity of all systems. The body will fail - it will begin to use its own muscle tissue as a protein. The “transportation” of oxygen, glucose, and useful cholesterol will gradually fail. Prolonged lack of amino acids will lead to serious consequences:

exhaustion (anorexia) will begin;
weakened defenses;
mental and intellectual processes slow down.

But this is only the beginning of a bad ending. Irreversible changes in the work of the pancreas, liver, gastrointestinal tract and hematopoiesis will begin. Especially dangerous is the lack of protein in childhood, when there is an increased growth and development of the whole organism.

As a result, the child has bone fragility, apathy, weakening of mental and physical abilities. Most often, protein deficiency occurs in the following categories of people:

Pregnant and lactating.
Vegetarians who eat only plant foods.
Patients with malignant tumors, massive bleeding, serious bodily injuries.

This group also includes people addicted to drugs and alcoholic beverages. The risk of amino acid deficiency increases in women who follow strict diets.

Important molecular compounds that ensure normal life

All essential amino acids are obtained from dietary sources. But here you need to understand and know which protein components are easily absorbed by the system and make a significant contribution to the development of the body. Nutritionists distinguish three food bases. The first category includes dairy products - breast colostrum for a newborn.

Up to about six months, the baby receives the necessary protein with the milk of his mother, this amount is quite enough for him. But with age, an additional source of amino acids is required. And here the problems with the choice begin. Dietetics advises to give preference to natural milk, preferably goat, proteins, low-fat cottage cheese and cheeses.

To build muscle and bone tissue, you should provide yourself with animal products - this is a natural and irreplaceable source of 20 important compounds. The daily consumption rate for the adult population is approximately 50-60%: veal, poultry, fish. It is advisable to alternate such a menu with plant foods: fresh fruits, herbs, vegetables, legumes, whole grain bread, buckwheat.

A balanced combination of these sources will keep health in order. But in everything you need to know the measure, this also applies to protein. Excess has a depressing effect on the intestinal microflora, causes dysbacteriosis, provokes the accumulation of uric acid and increases the risk of formation of stones in the kidneys.

There are people for whom protein is completely contraindicated and prohibited for use. Limit the portion of the compounds or completely exclude them in case of gout, acute form of nephritis and liver failure.

Fats

Squirrels

The physiological role of proteins consumed with food is that they are the main element of the body's plastic metabolism, being a source of "building material". Dietary proteins are broken down to their structural elements - amino acids. Products containing proteins cannot be replaced by products containing fats and carbohydrates Some of the amino acids that make up protein molecules can be synthesized in the body. These are the so-called non-essential amino acids. The other part ( essential amino acids) cannot be synthesized, so it must be supplied with food. The main sources of proteins for humans are: meat, eggs, fish, beans, peas, beans.

Unlike carbohydrates and fats, proteins do not accumulate and store in the body. If more of them are received with food than is necessary to meet current needs, hydrolysis products (amino acids) undergo biochemical changes and are included in metabolic reactions. Part of the amino acids not used as structural elements and energy material is deaminated. The remaining carbon sequences are transformed and included in carbohydrate metabolism reactions. The cleaved nitrogen is excreted from the body with urine in the form of urea.

Fats are an important part of the diet. They are part of many food products: meat, fish, milk. And products such as lard, butter, are almost entirely composed of fats. As a rule, vegetable fats differ from animal fats in that they contain more unsaturated fatty acids in their composition.

During hydrolysis in the body, fats (glycerides) are broken down into glycerol and fatty acids, some of which are essential because they cannot be synthesized in the human body (for example, some unsaturated acids - linoleic, linolenic).

Like other nutrients, fats take part in plastic And energy exchange. Their oxidation leads to the release of much more energy than the oxidation of proteins and carbohydrates. In addition, fats can accumulate in the body, forming a universal depot of energetically valuable material. Carbohydrates and part of the proteins that enter the body in excess can be transformed into fat, which leads to the growth of its deposits. If necessary, the fat stored in this way can be converted into glycogen and used in carbohydrate metabolism reactions.

Plant foods - fruits, vegetables, cereals - are the main source of carbohydrates for humans, the main of which is polysaccharide starch.

Carbohydrates - main source of energy in the body, since their breakdown is more accessible than the breakdown of lipids, although the breakdown of carbohydrates leads to the release of fewer calories than the degradation of the same amounts of fat. Carbohydrates can be stored in small amounts in liver And muscles as glycogen. The breakdown products of proteins and fats (amino acids and fatty acids), being transformed, are able to be included in carbohydrate metabolism.

Didn't find what you were looking for? Use the search:

Best sayings: Get carried away by a girl - tails will grow, study - horns will grow 9502 - | 7518 - or read all...