The physiological role of proteins in the body. Physiological role and hygienic importance of proteins, fats, carbohydrates, vitamins, minerals
Lecture No. 3
Topic: 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 foods.
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 to several hundred).
In the body, peptides are formed either during synthesis from amino acids, or during hydrolysis (breakdown) of protein molecules.
Today, the physiological significance and functional role of the most common groups of peptides, on which human health, organoleptic and sanitary properties of food products depend, have been established.
Peptide buffers. In the muscles of animals and humans, dipeptides have been found that perform buffer functions, that is, maintaining a constant pH level.
Peptide hormones. Hormones are organic substances produced by gland cells that regulate the activity of individual organs, glands and the body as a whole: contraction of the smooth muscles of the body and the 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, and hair. .
Neuropeptides. These are two groups of peptides ( endorphins And enkephalins ), contained in the brain of humans and animals. They determine behavioral reactions (fear, fear), influence the processes of memorization and 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 posed by toxins of microorganisms (Staphylococcus aureus, botulism bacteria, salmonella), including fungi, which 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.
Flavor peptides– primarily 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 (depending on the secondary, tertiary and quaternary structures).
Different food products differ in their qualitative and quantitative protein content.
In cereals 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 in 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%. Soybeans are the most widely used. Its score is close to one for five amino acids, but soy contains insufficient tryptophan, phenylalanine and tyrosine and a very low methionine content.
In oilseeds(sunflower, cotton, rapeseed, flax, castor bean, cariander) the total protein content is 14÷37%. At the same time, the amino acid score of proteins of all oilseeds (to a lesser extent of cotton) is quite high even for limiting acids. This fact determines the feasibility of obtaining concentrated forms of protein from oilseed raw materials and creating new forms of protein foods on their basis.
Relatively low nitrogen content in potatoes(about 2%), vegetables(1÷2%) and fruits(0.4÷1.0%) indicate the insignificant role of these types of food plant raw materials in providing food with protein.
Meat, milk and the products obtained from them contain proteins necessary for the body, which are favorably balanced and well digestible (at the same time, the balance and digestibility rate of milk is higher than that of meat). The protein content in meat products ranges from 11 to 22%. The protein content in milk ranges from 2.9 to 3.5%.
3 New forms of protein foods.
Today, in an ever-growing society and limited resources, people face 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 plant protein sources have received wide recognition: legumes, grains, cereals and their by-products, oilseeds; vegetables and melons, vegetative mass of plants.
At the same time, soybeans 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 from 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; they contain at least 90% protein.
Based on soy it is obtained 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, soybean-based products are also used to produce soy milk, soy sauce, tofu (bean curd) and other food products.
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 plant proteins determines their inferiority. The solution here is the joint use of different proteins, which provides a cross-fertilization effect. 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 we speak of mere 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 increases the digestibility of plant proteins by 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 physical and chemical characteristics that determine the behavior of proteins when processed 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 assessing 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; those with high hydrophilicity interact well with water. Since proteins of the same type have the same charge, 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 the adsorption of water with the participation of hydrophilic amino acid residues, fat-binding– adsorption of fat due to hydrophobic residues. On average, per 1 g of protein can bind and retain 2–4 g of water or fat on its surface.
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 environments, contribute to their distribution in each other, that is, the creation of stable systems.
Gelling The properties of proteins are characterized by the ability of their colloidal solution to transform 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 with which protein molecules bind to each other or to a solvent.
--- full-fledged
--- inferior
Classification of feed according to protein content. Protein nutrition standards for animals.
The level of protein nutrition of animals is determined by the amount of digestible protein per 1 unit, and in poultry farming - by the content of crude protein as a percentage of the dry feed mixture. For example, cows for 1 unit. the diet requires 100-110 g of digestible protein, pigs - 100-120 g, in the feed of laying hens 16-17% of crude protein.
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 fractions is necessary. It is desirable that cattle diets contain 40-50% water-salt fractions in crude protein. There are many such fractions in root crops and corn silage, and few in hay and haylage. In cattle, rumen microorganisms are also a source of protein.
The use of synthetic nitrogen-containing substances in feeding dairy cattle.
The use of non-protein nitrogen supplements in the feeding of ruminants is of practical importance. I use urea, biuret, urea phosphate, ammonium salts of sulfuric and phosphoric acid.
Consider carbamide (urea): During feeding, it hydrates to ammonia and CO 2. Through supplements, you can reduce your protein requirement by up to 25%.
For dairy cattle, the use of synthetics is important because... it replenishes the lack of nitrogen and protein during milk synthesis.
Ways to increase the protein nutritional value of feeds and diets. Preparation and use of AKD in animal husbandry.
Increased production of high protein feeds
Rational use of high-protein feeds
Use of protein substitutes in animal feeding
The importance of fats in animal nutrition. Contents in feed.
In the animal body, lipids perform the following functions:
Part of the structure of cell membranes
Basics of Nervous Tissue
Deposit energy
Protective role
Basics 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. The fat content in the body depends on age, type and fatness.
In feed of plant origin: fat in seeds and grains. More fat in oilseeds (soybeans, flax, cotton, etc. 30-40% of dry matter). In corn and oat grains – 5-6%. Wheat, rye – 1-2%. In the roots of tuber crops – 0.1-0.2%.
The source of lipids for ruminants is sunflower, cotton, and cakes. An effective way to feed fats is by adding additives to mixed feed and grass granules.
Pigs: vegetable oils have a negative effect on pork fat technology. Flaxseed oil, castor oil and marine animal fats are not recommended.
The need for fat is especially high 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. Contents in feeds and supplements.
Ca – 99% is in the skeleton, mineralization of bone tissue depends on the supply of Ca and P, the supply of vitamin D. With a deficiency: in young people – the processes of ossification of bones and tissue, curvature of the spine, stunted growth. In adult animals: a state of hypocalcemia, softening of bones (osteomalacia), immobilization of Ca and P from the bones.
Ca is necessary for normal excitability of nervous tissue, muscle contractility, and an important component of blood clotting.
Ca 2+ - stability of the cell membrane, cell adhesion during tissue formation.
In highly productive cows during lactation, softening of the last caudal vertebrae, curvature of the ribs, and a state of hypocalcemia. During the process of milk formation, the need for Ca increases sharply. The body of some animals is not able to obtain the required amount through effective use from feed, or skeletal immobilization (Ca is extracted from muscles).
Lack of Ca – muscle tremors, body temperature of sick cows below 37 0 C, hypocalcemia (postpartum paresis). In laying hens, bones, beaks, and limbs soften, and 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 feed 1.5 g/kg
Legumes 2.8 g/kg
The optimal ratio of Ca and P is 2:1
In animal blood serum, 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 of R. Normal. Contents in feeds and supplements.
In animals, phosphorus is closely related to calcium. It is part of bone tissue and is found in phosphoroproteins, nucleic acids and phospholipids. Phosphorus is necessary for the formation of bone tissue, the absorption of carbohydrates and fats. Phosphorus is an essential component of cellular proteins, serves as an activator of a number of enzymes, and is involved in creating 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. A lack of phosphorus in the diet causes muscle weakness, impaired fertility, and has a negative effect 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. Grain contains 3-4 g per 1 kg of dry matter, meal - 7.7, bran - 7-10 g. Root tuber crops contain little phosphorus - 1.4-2 g, carrots contain 4.7 g per 1 kg of dry matter, the concentration is much higher phosphorus in skim milk – 10 g, in fish meal 29 g per 1 kg of dry matter.
Value of Cu, Co, Mn, Zn. Norms. Contents in feed.
Cu– together with iron and vitamin B 12, copper is necessary for the normal course of the formation of hemoglobin, individual enzyme systems, hair growth and pigmentation, reproduction and lactation. Cu deficiency causes wasting, depigmentation and hair loss, growth retardation, anemia, fragility and underdevelopment of the spine, perverted appetite and diarrhea.
Co– necessary for rumen microorganisms to synthesize vitamin B12. Co deficiency leads to vitamin B 12 deficiency and manifests itself in weakness, exhaustion and death. Other symptoms of cobalt deficiency may include loss of appetite, eating hair and fur, scaly skin, and sometimes diarrhea.
Mn– found in the body in small quantities, disrupts the structure of bone tissue and reproductive function. Calves from cows deficient in manganese often have deformed limbs, thickened joints, stiffness, curvature, and low growth rate. Lameness is observed in pigs.
To compensate for the lack of manganese, manganese sulfate or manganese potassium is introduced into the diet.
In pasture grass, the manganese content 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 hair growth. Deficiency causes parakeratosis in calves and pigs. Symptoms of deficiency: slow growth, skin damage 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.
Physiological significance of proteins. Complete and incomplete proteins.
Protein plays a primary role in the construction of organs, tissues and vital functions of the animal body. Conventionally, 3 main functions of protein can be distinguished:
Plastic - serves as a building material for the synthesis of body proteins, and is also an integral part of manufactured 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 given to carbohydrates and fats.
According to the amino acid composition, a protein can be:
--- full-fledged– contain essential amino acids in sufficient quantities that cannot be synthesized in the body and must be obtained from food
--- inferior– do not contain these amino acids or are present in insufficient quantities, for example, corn grain, in which the crude protein is represented by a protein poor in amino acid composition - zein.
They carry food of animal origin, so to speak, because the concentration of amino acids in them is higher than in plant foods.
PROTEIN METABOLISM
Proteins occupy a leading place among organic elements, accounting for more than 50% of the dry mass of the cell. They perform a number of important biological functions. The entire complex of metabolism in the body (respiration, digestion, excretion) is ensured by the activity of enzymes, which are proteins. All motor functions of the body are ensured by the interaction of contractile proteins - actin and myosin.
Protein supplied with food from the external environment serves plastic and energy purposes. The plastic significance of the protein is the replenishment and new formation of various structural components of the cell. The energy value lies in providing the body with energy generated from the breakdown of proteins.
In tissues, processes of protein breakdown constantly occur, followed by the release of unused products of protein metabolism from the body and, along with this, protein synthesis. Thus, the proteins of the body are not in a static state; due to the continuous process of their destruction and formation, proteins are renewed. The rate of protein turnover is different for different tissues. The proteins of the liver, intestinal mucosa, as well as other internal organs and blood plasma are renewed at the highest speed. The proteins that make up the cells of the brain, heart, and gonads are renewed more slowly, and even more slowly the proteins of muscles, skin, and especially supporting tissues (tendons, bones, and cartilage).
Physiological significance of the amino acid composition of food proteins and their biological value
For normal protein metabolism, which is the basis for their synthesis, various amino acids must be supplied to the body with food. By changing the quantitative ratio between amino acids entering the body or excluding one or another amino acid from food, one can judge the importance of individual amino acids for the body based on the state of nitrogen balance, growth, weight and general condition of animals. It has been experimentally established that of the 20 amino acids that make up proteins, 12 are synthesized in the body (essential amino acids), and 8 are not synthesized (essential amino acids).
Without irreplaceable amino acids, protein synthesis is sharply disrupted and a negative nitrogen balance occurs, growth stops, and body weight falls. Long life of animals and their normal condition are impossible in the absence of at least one of the essential amino acids in food. For humans, essential amino acids are leucine, isoleucine, valine, methionine, lysine, threonine, phenylalanine, tryptophan.
Proteins have different amino acid compositions, and therefore the possibility of using them for the synthetic needs of the body varies. In this regard, the concept was introduced biological value food proteins. Proteins containing the entire necessary set of amino acids in such ratios that ensure normal synthesis processes are biologically complete proteins. On the contrary, proteins that do not contain certain amino acids or contain them in very small quantities will be inferior. Thus, incomplete proteins are gelatin, which contains only traces of cystine and lacks tryptophan and tyrosine, zein (a protein found in corn), containing little tryptophan and lysine, gliadin (wheat protein) and hordein (barley protein), containing little lysine. , and some others./The highest biological value of proteins is meat, eggs, fish, caviar, and milk.
In this regard, human food must not only contain a sufficient amount of protein, but must contain at least 30% proteins with high biological value, i.e., of animal origin.
In humans, there is a form of protein deficiency that develops with a monotonous diet of plant products with low protein content. This causes a disease called “kwashiorkor”. It is found among the population of tropical and subtropical countries in Africa, Latin America and Southeast Asia. This disease mainly affects children aged 1 to 5 years.
The biological value of one and the same protein is different for different people. Probably, it is not a specific value, but can vary depending on the state of the body, the preliminary nutritional regimen, the intensity and nature of physiological activity, food intake, individual metabolic characteristics and other factors.
It is practically important that two incomplete proteins, one of which does not contain some amino acids, and the other - others, in total can meet the body's needs. ,
Nitrogen balance
Nitrogen balance - the ratio of the amount of nitrogen entering the body with food and excreted from it. Since the main source of nitrogen in the body is protein, the nitrogen balance can be used to judge the ratio of the amount of protein received and destroyed in the body. The amount of nitrogen taken from food differs from the amount of nitrogen absorbed, since some of the nitrogen is lost in feces.
Nitrogen absorption is calculated by the difference in nitrogen content in food taken and in feces. Knowing the amount of nitrogen absorbed, it is easy to calculate the total amount of protein absorbed by the body, since protein contains on average 16% nitrogen, i.e. 1 g of nitrogen is contained in 6.25 g of protein. Therefore, by multiplying the found amount of nitrogen by 6.25, the amount of protein can be determined.
In order to determine the amount of protein destroyed, it is necessary to know the total amount of nitrogen excreted from the body. Nitrogen-containing products of protein metabolism (urea, uric acid, creatinine, etc.) are excreted mainly in urine and partially in sweat. Under conditions of normal, low-intensity sweating, the amount of nitrogen in sweat can be ignored. Therefore, to determine the amount of protein broken down in the body, the amount of nitrogen in the urine is usually found and multiplied by 6.25.
There is a certain relationship between the amount of nitrogen introduced with food proteins and the amount of nitrogen excreted from the body. An increase in protein intake into the body leads to an increase in nitrogen excretion from the body. In an adult with adequate nutrition, as a rule, the amount of nitrogen introduced into the body is equal to the amount of nitrogen removed from the body. This condition is called nitrogen balance. If, under conditions of nitrogen balance, you increase the amount of protein in food, then the nitrogen balance is soon restored, but at a new, higher level. Thus, nitrogen equilibrium can be established with significant fluctuations in protein content in food.
In cases where nitrogen intake exceeds its release, we speak of positive nitrogen balance. In this case, protein synthesis prevails over its breakdown. A stable positive nitrogen balance is always observed with an increase in body weight. It is observed during the period of growth of the body, during pregnancy, during the period of recovery after serious illnesses, as well as during intense sports training, accompanied by an increase in muscle mass. Under these conditions, nitrogen retention occurs in the body (nitrogen retention).
Proteins are not deposited in the body, that is, they are not stored in reserve. Therefore, when a significant amount of protein is consumed with food, only part of it is spent for plastic purposes, while the majority is spent for energy purposes.
When the amount of nitrogen excreted from the body exceeds the amount of nitrogen taken in, it is said to be negative nitrogen balance.
A negative nitrogen balance is observed during protein starvation, as well as in cases where the body does not receive certain amino acids necessary for protein synthesis.
Protein breakdown in the body occurs continuously. The degree of protein breakdown is related to the nature of nutrition. The minimum protein consumption under conditions of protein starvation is observed when eating carbohydrates. Under these conditions, the release of nitrogen can be 3-3"/2 times less than during complete starvation. Carbohydrates perform protein-sparing role.
The breakdown of proteins in the body, which occurs in the absence of proteins in food and the sufficient introduction of all other nutrients (carbohydrates, fats, mineral salts, water, vitamins), reflects those minimal expenses that are associated with basic life processes. These smallest protein losses for the body at rest, calculated per 1 kg of body weight, were called by Rubner wear rate.
The wear rate for an adult is 0.028-0.075 g of nitrogen per 1 kg of body weight per day.
Negative nitrogen balance develops when there is a complete absence or insufficient amount of protein in food, as well as when consuming food containing incomplete proteins. The possibility of protein deficiency with normal intake, but with a significant increase in the body's need for it, cannot be excluded. In all these cases there is protein fasting. "
During protein starvation, even in cases of sufficient intake of fats, carbohydrates, mineral salts, water and vitamins into the body, a gradually increasing loss of body weight occurs, depending on the fact that the costs of tissue proteins (minimal in these conditions and equal to the wear coefficient) are not compensated by the intake of proteins from food. Therefore, prolonged protein starvation ultimately, like complete starvation, inevitably leads to death. Protein starvation is especially difficult for growing organisms, which in this case not only lose body weight, but also stop growth due to a lack of plastic material necessary for the construction of cellular structures.
Modern science has achieved certain successes in the study of issues of rational nutrition. It is well known that it is based on proteins, fats, carbohydrates, as well as vitamins and minerals obtained from food.
Proteins, or proteins, are of greatest importance for the functioning of the body. They are the structural basis of all cells of the body and ensure their activity. Proteins perform a variety of functions, such as catalytic, structural, regulatory, signaling, transport, storage (reserve), receptor, motor (motor). Proteins in the human body are formed from food proteins, which, as a result of digestion, are broken down into amino acids, absorbed into the blood and used by cells. There are 20 amino acids, which are divided into non-essential (they are synthesized in the body) and essential, which come from food. Essential amino acids include valine, isoleucine, leucine, threonine, methionine, lysine, phenylalanine, tryptophan, arginine, histidine, methionine, lysine and tryptophan are considered especially important. They are found mainly in products of animal origin. Methionine is especially necessary for mental activity. Its highest content is in cottage cheese, eggs, cheese, and meat.
The average body need for protein is 1-1.3 g per kilogram of body weight. The daily diet of people with mental work should include proteins of both animal and plant origin. Their ratio is 45:55. Of the plant proteins, the proteins of soybean, potato, oatmeal, buckwheat, beans, and rice have the greatest value and biological activity.
Fats are the most concentrated source of energy. At the same time, they perform other important functions in the body: together with proteins they form the structural basis of cells, protect the body from hypothermia, and serve as natural sources of vitamins A, E, D. Therefore, fats and especially their main component - fatty acids - are an essential component food. Fatty acids are divided into saturated and unsaturated. Arachidonic and linoleic acids are among the most biologically valuable among unsaturated fatty acids. They strengthen the walls of blood vessels, normalize metabolism, and counteract the development of atherosclerosis. The ratio of animal and vegetable fats is 70:30.
Arachidonic acid is found only in animal fats (pork lard - 2%, butter - 0.2%). Fresh milk is also rich in this product.
Linoleic acid is found mainly in vegetable oils. Of the total amount of fats included in food, it is recommended to consume 30-40% vegetable fats. The body's need for fat is approximately 1-1.2 g per kilogram of weight. Excess fat leads to excess body weight, deposition of fatty tissue, and metabolic disorders.
Carbohydrates are a large group of organic compounds found in all living organisms. Carbohydrates are considered the body's main source of energy. In addition, they are necessary for the normal functioning of the nervous system, mainly the brain. It has been proven that during intense mental activity, carbohydrate consumption increases. Carbohydrates also play an important role in protein metabolism and fat oxidation, but their excess in the body creates fat deposits.
Carbohydrates come from food in the form of monosaccharides (fructose, galactose), disaccharides (sucrose, lactose) and polysaccharides (starch, fiber, glycogen, pectin), turning into glucose as a result of biochemical reactions. The body's need for carbohydrates is approximately 1 g per kilogram of body weight. Excessive consumption of carbohydrates, especially sugar, is extremely harmful.
The main sources of carbohydrates from food are: bread, potatoes, pasta, cereals, and sweets. Sugar is a pure carbohydrate. Honey, depending on its origin, contains 70-80% glucose and fructose. In addition, consumption of carbohydrates in the form of refined sugar and sweets contributes to the development of dental caries. Therefore, it is recommended to use more foods containing polysaccharides (porridge, potatoes), fruits and berries as sources of carbohydrates.
The average daily human need for carbohydrates is 4-5 g per kilogram of body weight. It is recommended to introduce 35% of carbohydrates in the form of granulated sugar, honey, jam, and the rest should preferably be replenished with bread, potatoes, cereals, apples, etc. http://www.ref.by/refs/89/20072/1 .html
It is impossible to overestimate the role of proteins, fats and carbohydrates for the body. After all, our body is made up of them! Today the site talks about how to eat so as not to upset such an important and fragile balance.
Proteins, fats and carbohydrates in our body
It has been reliably established that the human body consists of 19.6% proteins, 14.7% fats, 1% carbohydrates and 4.9% minerals. The remaining 59.8% comes from water. Maintaining the normal functioning of our body directly depends on the ratio of the most important nutrients, namely: the presence of proteins, fats and carbohydrates in a ratio of 1:3:5 is necessary in the daily diet.
Unfortunately, most of us do not pay due attention to a nutritious and balanced diet: some overeat, some undereat, and many even eat haphazardly, whatever they have to, on the go and in a hurry. In such a situation, it is almost impossible to control the amount of proteins, fats and carbohydrates entering the body with food. But there is a real danger of a deficiency or excess of one or several essential elements at once, which ultimately has a very negative impact on our health!
The importance of proteins, fats and carbohydrates for the body
The meaning and role of proteins
We also know from school textbooks that proteins are the main building material of our body, but in addition to this, they are also the basis of hormones, enzymes and antibodies. Thus, without their participation the processes of growth, reproduction, digestion and immune defense are impossible.
Proteins are responsible for inhibition and excitation in the cerebral cortex, hemoglobin protein performs a transport function (carries oxygen), DNA and RNA (deoxyribonucleic and ribonucleic acids) ensure the ability of the protein to transmit hereditary information to cells, lysozyme regulates antimicrobial protection, and a protein that is part of the optic nerve ensures the perception of light by the retina of the eye.
In addition, protein contains essential amino acids, on which its biological value depends. A total of 80 amino acids are known, but only 8 of them are considered essential, and if all of them are contained in a protein molecule, then such a protein is called complete, animal in origin, and it is found in products such as meat, fish, eggs and milk.
Plant proteins are slightly less complete and more difficult to digest because they have a fiber shell that interferes with the action of digestive enzymes. On the other hand, vegetable protein has a powerful anti-sclerotic effect.
To maintain the balance of amino acids, it is advisable to eat foods containing both animal and plant proteins, but the proportion of animal proteins should be at least 55%.
Excessive fat consumption leads to excess cholesterol, the development of atherosclerosis, deterioration of fat metabolism and accumulation of excess weight. A lack of fat can cause dysfunction of the liver and kidneys, water retention in the body, and the development of dermatoses.
To optimize your diet, it is necessary to combine both vegetable and animal fats in a ratio of 30% to 70%, but with age, preference should be given to vegetable fats.
About carbohydrate balance
The name of the class of these compounds comes from the term “carbon hydrates”, proposed back in 1844 by Professor K. Schmidt.
Carbohydrates serve as the main source of energy, providing 58% of the human body's needs. Products of plant origin contain carbohydrates in the form of mono-, di- and polysaccharides.
