Proteins – their role in the human body and how important they are in sports. Proteins in human nutrition: effects on the body

What do we know about the proteins that we consume daily with food? Most people are familiar with them as muscle building materials. But this is not their most important task. What else do we need protein for and why do we need it so much? Let's look at all the functions of proteins in the human body and their importance in our diet.

I already started a protein topic on the blog “Lead a Healthy Lifestyle.” Then we talked about whether protein is harmful or not. The topic of sports nutrition is now very popular among novice athletes. Therefore, I could not help but touch on it. Read more.

Being the main component of all cells and organic tissues, proteins play extremely important role in the smooth functioning of the body. They actively participate in absolutely all vital processes. Even our thinking is directly related to this high-molecular organic substance. I'm not even talking about metabolism, contractility, the ability to grow, irritability and reproduction. All these processes are impossible without the presence of proteins.

Proteins bind water and thereby form dense structures in the body, characteristic of human body, colloidal structures. Famous German philosopher Friedrich Engels said that life is the mode of existence of proteins that constantly interact with their environment through continuous metabolism, and as soon as this exchange stops, the protein decomposes - life itself ends.

New cells cannot be born without the participation of protein. Its main task is construction. He is the builder of young cells, without which the development of a growing organism is impossible. When this organism stops growing and reaches mature age, cells that have already outlived their usefulness need regeneration, which takes place only with the participation of protein.

For this process, its amount must be proportional to the wear of the fabrics. Therefore, people who lead a sporting life associated with muscle loads (for example) need to consume more protein. The higher the load on the muscles, the more their body needs regeneration and, accordingly, protein food.

Role of specific proteins

The body must be maintained constant balance specific proteins. They consist of hormones, various antibodies, enzymes and many other formations that are directly involved in the most important functions for normal life. biochemical processes. The functions that these proteins perform are very subtle and complex. We must maintain their quantity and composition in the body at a constant level.

Protein is a complex biopolymer containing nitrogen. Its monomers are α-amino acids. Protein, depending on its type, consists of various amino acids. It is by the amino acid composition that the biological value of a protein is judged. Molecular weight of proteins: 6000-1000000 or more.

Amino acids in proteins

What are amino acids? These are organic compounds that consist of two functional groups:

carboxyl (-COOH-) - the group that determines acid properties molecules;
amino group (-NH2-) is a group that gives molecules basic properties.

There are many, many natural amino acids. There are only 20 of them in food proteins.

There are many, many natural amino acids. Food proteins contain only 20 of them:
alanine, arginine, asparagine, aspartic acid, valine, histidine, glycine (glycocol), glutamine, glutamic acid, isoleucine, leucine, lysine, methionine, proline, serine, tyrosine, threonine, tryptophan, phenylalanine, cystine.

Essential amino acids are 8 of the 20 listed above. These are valine, isoleucine, lysine, leucine, threonine, tryptophan, phenylalanine, methionine. They are called essential because we can only get them from food. Such amino acids are not synthesized in our body. In children under one year of age, histidine is also an essential amino acid.

If the body suffers from a deficiency of one of the essential amino acids or an imbalance in their composition, then malfunctions begin in the body. Protein synthesis is disrupted and various pathologies can occur.

What types of proteins are there?

All proteins found in food products are divided into simple and complex. Simple proteins are also called proteins, and complex proteins are called proteids. They differ in that simple ones consist only of polypeptide chains, while complex ones, in addition to the protein molecule, also contain a prosthetic group - a non-protein part. If we talk in simple language, then proteins are pure protein, and proteids are not pure protein.

Proteins are also divided according to their spatial structure into globular and fibrillar. Molecules of globular proteins have a spherical or ellipsoidal shape, while molecules of fibrillar proteins have a filamentous shape.

Simple globular proteins: albumins and globulins, glutelins and prolamins.

Contains milk, whey, egg white includes albumins and globulins. In turn, glutelins and prolamines are plant proteins found in cereal seeds. They form the bulk of gluten. Plant proteins are poor in lysine, leucine, methionine, threonine and tryptophan. But they are rich in glutamic acid.

The supporting function in the body is performed by structural proteins (protenoids). They belong to fibrillar proteins of animal origin. They are also resistant to digestion by digestive enzymes and are generally insoluble in water. Protenoids include keratins (they contain a lot of cystine), collagen and elastin. The latter two contain few sulfur-containing amino acids. In addition, collagen is rich in hydroxyproline and oxylysine and does not contain tryptophan.

Collagen becomes water soluble and turns into gelatin (glutin) through prolonged boiling. In the form of gelatin, it is used to prepare many culinary dishes.

Complex proteins include glyco-, lipo-, metallo-, nucleo-, chromo- and phosphoproteins.

Functions of proteins in the human body

Plastic function - provide the body with plastic material. Protein is a building material for cells, the main component of absolutely all enzymes and most hormones.
Catalytic function - act as accelerators of all biochemical processes.
Hormonal function - are integral part most hormones.
Specificity function - provides both individual and species specificity, which forms the basis for the manifestation of both immunity and allergies.
Transport function - protein is involved in the transport of oxygen, some vitamins, minerals, carbohydrates, lipids, hormones and other substances in the blood.

We can only get protein through food. The body does not have reserve reserves. This is an indispensable component of the diet. Just don’t get too carried away with protein foods, as this can lead to poisoning of the body and active reproduction.

Proteins and nitrogen balance

In a healthy body, nitrogen balance is constantly maintained. The so-called state of nitrogen equilibrium. This means that the amount of nitrogen entering the body with food must be equal to the amount of nitrogen excreted from the body along with urine, feces, sweat, peeling of the skin, nails, and hair.

There are concepts of positive nitrogen balance (the amount of nitrogen being excreted is less than that of incoming nitrogen) and negative nitrogen balance (the amount of nitrogen being excreted is greater than that of incoming nitrogen). A positive nitrogen balance is usually observed in those recovering from serious illnesses and children. This is due to their process of constant growth of children. In addition, such a balance takes place.

If the processes of protein catabolism prevail over the processes of synthesis (fasting, vomiting, protein-free diet, anorexia), or adsorption of proteins occurs in the digestive system, or the process of protein breakdown due to severe diseases occurs, then there is a negative nitrogen balance.

Deficiency and excess of proteins

Proteins, entering the body along with food, are oxidized and supply the body with energy.

16.7 kJ of energy (4 kcal) is released from the oxidation of just 1 g of protein.

During fasting, the body's consumption of protein as a source of energy sharply increases.

Proteins, entering the stomach along with food, are broken down into amino acids. These amino acids are then absorbed by the intestinal mucosa and go straight to the liver. And from there, amino acids are sent to all other organs and connective tissues for the purpose of synthesizing proteins in the human body.

Protein deficiency

If the food in your daily diet does not contain sufficient quantity protein - its deficiency, then this will most likely lead to protein deficiency. Mild protein deficiency may occur if balanced nutrition, for a number of diseases leading to impaired protein absorption, increased catabolism and other disorders of the metabolism of proteins and amino acids.

Excess protein

In addition to deficiency, there is also an excess of proteins in the body. In this case, the digestive and excretory systems undergo severe stress, which leads to the formation of rotting products in the digestive canal. And this causes intoxication and poisoning of the entire body.

These are the functions of proteins in the body. There is only one conclusion that can be drawn. You need to maintain proper balanced nutrition.

What is protein and how does it work, as well as its content in food and how much is needed for absorption by the body.

Any cells develop, grow and renew themselves thanks to protein - a complex organic substance, a catalyst for all bio chemical reactions. The state of DNA, hemoglobin transport, fat breakdown are far from full list continuous functions performed by this substance for a full life. The role of proteins is enormous, extremely important and requires close attention.

What is protein

Proteins (proteins/polypeptides) - organic substances, natural polymers containing twenty interconnected . The combinations provide many views. The body copes with the synthesis of twelve essential amino acids on its own.

Eight of the twenty essential amino acids found in protein cannot be independently synthesized by the body; they are obtained from food. These are valine, leucine, isoleucine, methionine, tryptophan, lysine, threonine, and phenylalanine, which are important for life.

What kind of protein is there?

There are animal and plant (based on origin). Two types are required.

Animal:

Meat;
Fish;
Milk products;
Eggs.

Egg white is easily and almost completely absorbed by the body (90-92%). The proteins of fermented milk products are slightly worse (up to 90%). Fresh proteins whole milk are absorbed even less (up to 80%).
The value of beef and fish is best combination essential amino acids.

Vegetable:

Cereals, cereals;
Legumes;
Nuts;
Fruits.

Soybeans, rapeseed and cottonseeds have a good ratio of amino acids for the body. In grain crops this ratio is weaker.

There is no product with an ideal amino acid ratio. Proper nutrition involves a combination of animals and vegetable proteins.

The basis of nutrition “according to the rules” is animal protein. It is rich in essential amino acids and ensures good absorption of plant protein.

Functions of protein in the body

Being in tissue cells, it performs many functions:

Protective. The functioning of the immune system is the neutralization of foreign substances. Antibodies are produced.
Transport. Supply various substances, for example, (oxygen supply).
Regulatory. Maintaining hormonal levels.
Motor. All types of movement are provided by actin and myosin.
Plastic. The condition of connective tissue is controlled by collagen content.
Catalytic. It is a catalyst and accelerates the passage of all biochemical reactions.
Preservation and transmission of genetic information (DNA and RNA molecules).
Energy. Supplying the entire body with energy.

Others provide breathing, are responsible for the digestion of food, and regulate metabolism. The light-sensitive protein rhodopsin is responsible for visual function.

Blood vessels contain elastin, thanks to which they function fully. The protein fibrinogen ensures blood clotting.

Symptoms of lack of protein in the body

Protein deficiency is quite common occurrence with poor nutrition and hyper active image life of a modern person. IN mild form is expressed in regular fatigue and deterioration in performance. With growth insufficient quantity The body signals through symptoms:

General weakness and dizziness. Decreased mood and activity, the appearance of muscle fatigue without much physical activity, deterioration in coordination of movements, weakening of attention and memory.
Headaches and poor sleep. Appearing insomnia and anxiety indicate a lack.
Frequent changes mood, grouchiness. A lack of enzymes and hormones provokes depletion of the nervous system: irritability for any reason, unreasonable aggressiveness, emotional incontinence.
Pale skin, rashes. With a lack of iron-containing protein, anemia develops, the symptoms of which are dry and pale skin and mucous membranes.
Swelling of the limbs. Low protein content in blood plasma disrupts the water-salt balance. Subcutaneous fat accumulates fluid in the ankles and ankles.
Poor healing of wounds and abrasions. Cell restoration is inhibited due to a lack of “building material”.
Hair fragility and loss, brittle nails. The appearance of dandruff due to dry skin, peeling and cracking of the nail plate is the most common signal from the body about a lack of protein. Hair and nails are constantly growing and instantly respond to a lack of substances that promote growth and good condition.
Unreasonable weight loss. Disappearance of kilograms without apparent reason due to the body’s need to compensate for the lack of protein through muscle mass.
Malfunction of the heart and blood vessels, shortness of breath. The functioning of the respiratory, digestive, genitourinary systems. Shortness of breath appears without physical exertion, cough without colds and viral diseases.

With the appearance of symptoms of this kind, you should immediately change the diet and quality of food, reconsider your lifestyle, and if they worsen, consult a doctor.

How much protein is needed for absorption?

The daily consumption rate depends on age, gender, type labor activity. Data on standards are presented in the table (below) and are calculated for normal weight.
It is not necessary to split your protein intake into several doses. Everyone determines the form that is convenient for themselves, the main thing is to maintain daily norm consumption.

Labor activity +	Age period	Protein intake per day, g
		For men		For women
		Total	Animal origin	Total	Animal origin
Without load	18-40	96	58	82	49
Without load	40-60	89	53	75	45
Minor degree	18-40	99	54	84	46
Minor degree	40-60	92	50	77	45
Average degree	18-40	102	58	86	47
Average degree	40-60	93	51	79	44
High degree	18-40	108	54	92	46
High degree	40-60	100	50	85	43
Periodic	18-40	80	48	71	43
Periodic	40-60	75	45	68	41
Retirement age		75	45	68	41

Recognized protein-containing foods:

Poultry meat. Contents 17÷22 g (per 100 g);
Other meat: 15÷20 g;
Fish: 14÷20 g;
Seafood: 15÷18 g;
Legumes: 20÷25 g;
Any nuts: 15÷30 g;
Eggs: 12 g;
Hard cheeses: 25÷27 g;
Cottage cheese: 14÷18 g;
Cereals: 8÷12 g;

Of all types of meat, beef will be in first place after poultry in terms of content: 18.9 g. After it, pork: 16.4 g, lamb: 16.2 g.

The leading seafood products are squid and shrimp: 18.0 g.
The richest fish in protein is salmon: 21.8 g, followed by pink salmon: 21 g, pike perch: 19 g, mackerel: 18 g, herring: 17.6 g and cod: 17.5 g.

Among dairy products, kefir and sour cream hold their positions firmly: 3.0 g, then milk: 2.8 g.
High content cereals – Hercules: 13.1 g, millet: 11.5 g, semolina: 11.3 g.

Knowing the norm and taking into account financial capabilities, you can competently create a menu and be sure to supplement it with fats and carbohydrates.

Protein ratio in diet

The proportion of proteins, fats, carbohydrates in a healthy diet should be (in grams) 1:1:4. The key to balancing a healthy dish can be presented differently: proteins 25-35%, fats 25-35%, carbohydrates 30-50%.

In this case, the fats should be healthy: olive or linseed oil, nuts, fish, cheese.

Carbohydrates on the plate are durum pasta, any fresh vegetables, as well as fruits/dried fruits, dairy products.

Proteins per serving can be combined as desired: plant + animal.

Amino acids contained in protein

Replaceable ones can be synthesized by the body itself, but their supply from the outside is never superfluous. Especially with an active lifestyle and heavy physical activity.

All of them are important, without exception, the most popular of them are:

Alanin.
Stimulates metabolism, promotes the elimination of toxins. Responsible for “cleanliness”. High content in meat, fish, dairy products.

Arginine.
Necessary for contraction of any muscle healthy skin, cartilage and joints. Provides work immune system. Found in any meat, milk, any nuts, gelatin.

Aspartic acid.
Provides energy balance. Improves the functionality of the central nervous system. Well replenished energy resource beef and chicken dishes, milk, cane sugar. Contained in potatoes, nuts, cereals.

Histidine.
The main “builder” of the body is transformed into histamine and hemoglobin. Quickly heals wounds and is responsible for growth mechanisms. Relatively high in milk, cereals and any meat.

Serin.
A neurotransmitter, indispensable for the smooth functioning of the brain and central nervous system. Found in peanuts, meat, cereals, soybeans.

With proper nutrition and a proper lifestyle, the body will have all the amino acids for the synthesis of “cubes” and modeling health, beauty and longevity.

What does a lack of protein in the body lead to?

Frequent infectious diseases, weakened immune system.
Stress and anxiety.
Aging and slowdown of all metabolic processes.
Side effect from the use of certain medications.
Malfunctions of the gastrointestinal tract.
Injuries.
Meals based on fast food, products instant cooking, low quality semi-finished products.

A deficiency of any one amino acid will stop the production of a particular protein. The body is designed on the principle of “filling voids”, so the missing amino acids will be extracted from other proteins. This “rearrangement” disrupts the functioning of organs, muscles, heart, brain and subsequently provokes disease.

Protein deficiency in children inhibits growth and causes physical and mental disabilities.
Development of anemia, appearance skin diseases, pathologies of bone and muscle tissue are far from full list diseases. Severe protein dystrophy can result in marasmus and kwashiorkor ( type of severe dystrophy due to protein deficiency).

When does protein harm the body?

excessive intake;
chronic diseases liver, kidneys, heart and blood vessels.

An overabundance does not happen often due to incomplete absorption of the substance by the body. Occurs in those who want to increase muscle mass as soon as possible without following the recommendations of trainers and nutritionists.

The problems of “extra” intake include:

Kidney failure . Excessive amounts of protein overload organs, disrupting their natural functioning. The “filter” cannot cope with the load, and kidney diseases appear.

Liver diseases. Excess protein accumulates ammonia in the blood, which worsens liver health.

Development of atherosclerosis. Most animal products, in addition to useful substances, contain harmful fats and.

People suffering from pathologies of the liver, kidneys, cardiovascular and digestive systems should limit protein intake.

Taking care of your own health is rewarded a hundredfold to those who care about it. To avoid serious consequences, you need to remember the body’s need for recovery. Complete rest, nutrition, visiting specialists will prolong youth, health and life.

Proteins are the most important class organic matter, of which a person consists, constantly needs them.

The enormous importance of proteins for the body is due to their functions.

Plastic. Human tissues are made from proteins. On average, proteins occupy 45% of the dry matter mass throughout the body. Maximum content detected in muscles. It reaches 34.7% of the total amount of protein in the body. Contents in bone tissue is 18.7% of the total concentration. The skin contains 11.5% protein substances. Other proteins have been identified in teeth, brain and nerve tissue, liver, spleen, heart, kidneys. The structural and plastic role of proteins in the body can be realized with a constant supply quality products nutrition.

Energy. Oxidizing in the human body, proteins supply energy in the amount of 4 kcal from 1 gram. This is a significant component in the overall energy balance.

Catalytic. During life, hundreds of biochemical processes occur simultaneously in the human body. This is only possible thanks to enzymatic acceleration. Modeling similar reactions outside living systems would require a large amount of time, measured in hours or weeks. All enzymes are made from proteins. Without protein substances, the activity of biological catalysts is not feasible.

Regulatory. All processes in the human body are regulated by specific substances - hormones, which are formed in the glands internal secretion. Chemical nature hormones are different. Many hormones are proteins, for example, insulin, some pituitary hormones. Insufficient intake of protein substances into the body can provoke hormonal changes.

Transport. Transporter proteins deliver a variety of molecules throughout the body. For example, hemoglobin supplies oxygen to all organs, capturing it in surface layers lung tissue, releasing at the place of delivery.

Protective. Demonstrated by proteins such as interferon and globulins. The protection mechanisms implemented are different. For example, immunoglobulins, being antibodies, bind foreign pathogens into inactive complexes. Interferon neutralizes the ability of viruses to reproduce. Biological catalyst proteins, lysozymes, break down bacterial cells. The protective physiological role of protein makes it possible for a person to live surrounded by pathogenic “neighbors.”

Buffer. In human liquid systems, in particular in the blood, for the normal functioning of the body, a constant acidity of the environment must be maintained. When it changes due to various factors, buffer proteins can restore a constant composition. Hemoglobin has a particularly pronounced buffering ability.

Receptor. Rarely does anyone think about the operation of the most complex information transmission system in the human body. Necessary participants in this process are protein receptors. The receptor role of a protein in a cell is reduced to launching a chain of biochemical transformations, as a result of which we respond to signals. For example, in order for us to withdraw our hand from a hot object, protein receptors must fire. If their functioning is disrupted, normal activity of the body becomes impossible. The retina of the eye also perceives color optical waves using a protein receptor called rhodopsin.

The presented main functions of proteins illustrate the importance of this class of substances in ensuring normal human life.

In the 19th century, scientists stated:

protein bodies are unique, they are the essence of life;
constant exchange of substances between living beings and the surrounding nature is necessary.

These provisions remain unchanged to this day.

Basic composition of proteins

The huge molecular units of a simple protein, called a protein, are formed by chemically linked small blocks - amino acids with identical and different fragments. Such structural compositions are called heteropolymers. Only 20 representatives of the amino acid class are always found in natural proteins. The basic composition of proteins is characterized by the obligatory presence of carbon - C, nitrogen - N, hydrogen - H, oxygen - O. Sulfur - S is often found. Complex proteins called proteids contain other substances in addition to amino acid residues. Accordingly, they may contain phosphorus - P, copper - Cu, iron - Fe, iodine - I, selenium - Se.

Aminocarboxylic acids of natural proteins are classified according to their chemical structure and biological importance. Chemical classification is important for chemists, biological classification is important for everyone.

In the human body there are constantly two streams of transformations:

splitting, oxidation, disposal of food products;
biological synthesis of new necessary substances.

12 amino acids from those always found in natural proteins can be created by biological synthesis in the human body. They are called replaceable.

8 amino acids are never synthesized in humans. They are irreplaceable and must be supplied regularly with food.

Based on the presence of essential aminocarboxylic acids, proteins are divided into two classes.

Everyone has complete proteins necessary for the body human amino acids. The required set of essential amino acids includes proteins from cottage cheese, dairy products, poultry, cattle meat, sea and freshwater fish, and eggs.

In defective proteins of one or more important acids may not be enough. These include plant proteins.

To assess the quality of food proteins, the world medical community compares them with an “ideal” protein, which has strictly adjusted proportions of nonessential and especially important essential amino acids. There is no “ideal” protein in nature. Animal proteins come closest to it. Plant proteins often lack one or more amino acids to the required concentration. If the missing substance is added, the protein will become complete.

Main sources of proteins of plant and animal origin

In the domestic scientific community engaged in the comprehensive study of food chemistry, the group of Professor A.P. Nechaev, his colleagues and students stands out. The team determined the protein content in basic food products available on the Russian market.

Important! The identified figures inform about the protein content in 100 grams of product, freed from the inedible part.

Protein content in plant foods

The largest amount of protein is found in soybeans, pumpkin seeds, and peanuts (34.9 - 26.3 g).
Values from 20 to 30 g were found in peas, beans, pistachios, and sunflower seeds.
Almonds, cashews, hazelnuts are characterized by numbers from 15 to 20 grams.
Walnuts, pasta, most cereals (except rice, corn grits) contain from 10 to 15 grams of protein per 100 grams of product.
The range from 5 to 10 grams includes rice, corn grits, bread, garlic, dried apricots.
In 100 grams of cabbage, mushrooms, potatoes, prunes, and some varieties of beets, the protein content ranges from 2 to 5 grams.
Raisins, radishes, carrots, Bell pepper have little protein, their indicators do not exceed 2 grams.

If you were unable to find a plant object here, it means that the concentration of protein in it is too low or it is not there at all. For example, in fruit juices There is very little protein in natural vegetable oils- not at all.

Protein content in animal products

The maximum protein concentration was found in fish roe, hard and processed cheeses, and rabbit meat (from 21.1 to 28.9 g).
A large number of products contain from 15 to 10 grams of protein. This is a bird sea fish(except capelin), cattle meat, shrimp, squid, cottage cheese, feta cheese, freshwater fish.
Capelin, chicken eggs, and pork contain from 12.7 to 15 grams of protein per 100 grams of product.
Yogurt and curd cheeses are characterized by the numbers 5 – 7.1 g.
Milk, kefir, fermented baked milk, sour cream, and cream contain from 2.8 to 3 grams of protein.

Information about the main sources of proteins of plant and animal origin in products that have undergone multi-stage technological processing (stew, sausages, ham, sausages) is not of interest. They are not recommended for regular healthy eating. Short-term use of such products is not significant.

The role of protein in nutrition

As a result of metabolic processes in the body, new protein molecules are constantly formed to replace the old ones. The rate of synthesis in different organs is not the same. Proteins of hormones, for example, insulin, are restored (resynthesized) very quickly, within hours, minutes. The proteins of the liver and intestinal mucosa are regenerated in 10 days. Protein molecules of the brain, muscles, and connective tissue take the longest to recover; restoration synthesis (resynthesis) can last up to six months.

The process of utilization and synthesis is characterized by nitrogen balance.

In a mature person in full health nitrogen balance is zero. In this case, the total mass of nitrogen supplied with proteins during nutrition is equal to the mass excreted with decomposition products.
Young organisms develop intensively. The nitrogen balance is positive. A lot of protein comes in, less is excreted.
Aging, sick people have a negative nitrogen balance. The amount of nitrogen released with metabolic products is greater than that received during food intake.

The role of protein in nutrition is to provide a person with the required amount of amino acid components suitable for participation in the biochemical processes of the body.

To ensure normal metabolism, it is important to know how much protein a person needs to consume per day.

Domestic and American physiologists recommend eating 0.8 - 1 g of protein per 1 kg of human weight. The numbers are quite average. The amount depends greatly on the age, nature of work, and lifestyle of the person. On average, it is recommended to consume from 60 grams to 100 grams of protein per day. For men engaged in physical work, the norm can be increased to 120 grams per day. For people who have had surgical operations, infectious diseases, the norm also increases to 140 grams per day. Diabetics are recommended diets with increased content protein products, which can reach 140g per day. People with metabolic disorders and a tendency to gout should consume significantly less protein. The norm for them is 20 - 40 grams per day.

For people involved in active sports that increase muscle mass, the norm increases significantly and can reach 1.6-1.8 grams per 1 kg of the athlete’s weight.

Important! It is advisable to clarify the answer to the question with the trainer - how much protein should be consumed per day during exercise. Professionals have information about energy costs for all types of training, ways to maintain the normal functioning of the athlete’s body.

For the implementation of all physiological functions, it is important not only the presence of essential amino acids in protein, but also the efficiency of their absorption. Protein molecules have different levels organization, solubility, degree of accessibility to digestive enzymes. 96% of milk and egg proteins are broken down effectively. In meat and fish, 93-95% of proteins are safely digested. The exception is skin and hair proteins. Plant protein-containing products are digested by 60-80%. 80% of proteins are absorbed in vegetables, 70% in potatoes, 62-86% in bread.

Lack of protein in the body leads to significant changes in metabolism. Such pathologies are called dystrophy, kwashiorkor. For the first time, the disorder was identified in the inhabitants of wild tribes in Africa; it is characterized by a negative nitrogen balance, intestinal dysfunction, muscle atrophy, and growth arrest. Partial protein deficiency may occur similar symptoms, which can be expressed moderately for some time. A lack of protein in a child’s body is especially dangerous. Such dietary disorders can provoke physical and intellectual disability in a growing person.

Excess protein in the body overloads the excretory system. The load on the kidneys increases. If there are existing pathologies in renal tissue the process may get worse. It is very bad if an excess of protein in the body is accompanied by a lack of other valuable food components. In ancient times, in Asian countries, there was a method of execution in which the convicted person was fed only meat. As a result, the criminal died from the formation of rotting products in the intestines, followed by poisoning.

A reasonable approach to providing the body with protein guarantees the effective functioning of all vital systems.

Properties squirrel depend both on its composition and on the arrangement of amino acids in the molecule. Moreover, the order of amino acids in a protein molecule plays a very important role in the performance of their functions.

Amino acids, synthesized in our body, are called replaceable. Some amino acids are not formed in the human body - these are essential amino acids. Proteins containing the entire set of essential amino acids are biologically complete. They are found both in animal foods and in some food plants- soybeans, peas, beans.

If we accept value of milk proteins(it contains all essential amino acids) for 100, then biological value meat and fish can be expressed by the number 95, potatoes - 85, rye bread- 75, rice - 58, peas - 55, wheat - 50.

Everything must be supplied with food essential amino acids, a deficiency of at least one of them can lead to the death of the body, since each of the essential amino acids affects certain of its functions.

Great protein valueV not only in digestion, but also in all human life. Enzymes are built from proteins - biological catalysts that accelerate the course of chemical reactions occurring in the body.

And what meat food makes people irritable and cruel, by analogy with predatory animals, and also does not stand up to criticism. After all, as advocates of vegetarianism argue: “Herbivorous animals are distinguished by an easy-going disposition, even nature has not deprived them of strength and power. Take for example the elephant - it is powerful and kind, while lions are characterized by ferocity and bloodthirstiness.” Although zoological arguments, and we have already understood this, are much contradictory, it is not difficult to see that in these primitive reasoning, causes are replaced by consequences: it is not meat food that makes predators predatory, but people of a certain type aggressive and socially dangerous. According to this reasoning, it turns out that if a lion is fed with carrots, it will become quiet, like a rabbit, and a rabbit will go wild from meat. But for some reason it seems to me that both will die before they have time to get used to food that is unusual for them.

An uncompromising vegetarian, in order to get 50-70 g of fat, must eat 4-5 kg of plant products daily, and at least 70% of them should be oilseeds. Thus, partial and especially complete refusal from animal products today can also be considered as a kind of tribute to “fashionable” diets.

What protein is involved in muscle tissue formation, as if it goes without saying, but not everyone knows that he also participates in skeleton construction.

This is due to the fact that protein food helps the absorption of calcium, while a decrease in the level of protein in food impairs the absorption of this element by the intestinal mucosa. But more than 90% of calcium is concentrated in human bones: it is this element that gives strength to the skeleton. However, the functions of calcium in the body are not limited to this; it increases the excitability of the neuromuscular system, promotes blood clotting, reduces the permeability of the walls blood vessels. Calcium is involved in the work of the heart muscle, promotes the implementation therapeutic effect cardiac glycosides, stimulates liver function, activates the enzyme lipase. Therefore, protein foods enriched with calcium, especially milk and dairy products, are biologically more complete compared to foods of purely plant origin with a low calcium content.

Calcium deficiency in the body, provoked by the rejection of animal proteins, leads to disruption of a number of physiological functions, in particular, mental and physical performance, in children, bone formation is inhibited, and in adults, bones are resorbed.

The following historical example is very indicative in this regard.

In 1857, 8 years old Vanya Pavlov, future laureate Nobel Prize, fell from a high platform and after that began to fall seriously ill. Maybe the boy would not have survived if his godfather, the abbot of the suburban Trinity Monastery, had not taken him to his place. The old man knew healing power protein nutrition and therefore fed his godson eggs, milk and boiled chickens. In the mornings he did gymnastics with him, in the summer he made him swim, ride a horse, play gorodki, and in the winter he made him shovel snow and skate. The boy always and willingly helped the abbot tend the garden and vegetable garden. The abbot himself was distinguished by enviable health, which he confidently believed was a consequence of a healthy diet. Later, Ivan Petrovich Pavlov wrote that indifference to food is imprudence, and more than once said that it was thanks to proper nutrition retained high performance, endurance and clarity of thought until his full 86 years.

A completely opposite metamorphosis occurred with another representative of the Russian intelligentsia, who decided to old age become a vegetarian. Unlike little Vanya, who was sick in childhood, little Levushka was an unusually healthy boy, and even in his mature years, while fighting near Sevastopol, Lev Nikolaevich did not complain about his health. Having retired and, according to V.I. Ulyanov-Lenin’s definition, becoming a “hardened man,” Tolstoy amazed those around him physical health, carrying water, riding a bicycle and skating at almost 80 years old. True, worldwide famous writer He stopped eating meat only in his old age after he saw the scene at the Tula slaughterhouse, when they began to tear off the skin from a fallen bull, and life was still beating in the huge body of the animal and large tears were rolling from his blood-stained eyes. Back in Yasnaya Polyana, Lev Nikolaevich, for purely moral reasons, completely abandoned meat and his appearance literally immediately began to change. This is what his wife Sofya Andreevna wrote 7 years before the writer’s death: “It’s so painful for me to see him suffering, weak, fading and oppressed in spirit and body. Take his head in both hands or kiss his emaciated hands with tender, careful caress, and he’ll look indifferently. Something is happening in him, what is he thinking?" The change that occurred with L.N. Tolstoy after switching from his usual mixed food to plant-based food is completely understandable and completely explainable.

Dietary protein deficiency negatively affected the functioning of his body. First of all, the nitrogen balance was disrupted, and protein breakdown began to prevail over its synthesis. Experiencing a lack of protein, the body began to “feed” on its own tissues. It is not surprising that seven years later, the final clouding of his mind led Tolstoy to death.

Protein deficiency in nutrition, it reduces the body’s resistance to infections, as the level of antibody formation decreases. The synthesis of other protective factors - lysozyme and interferon - is also disrupted, which aggravates the course of inflammatory processes. Reducing the intake of protein from food, or increasing its consumption in the body (in severe physical work or as a result of illness) causes protein deficiency. A severe form of protein deficiency is called kwashiorkor. This disease occurs more often in children. In Russia, kwashiorkor is not observed, but the disease is often found in developing countries Asia, Africa, Central and South America.

Lack of compensation squirrel in the body has an adverse effect on activity cardiovascular, respiratory and other systems. Lack of protein impairs appetite, which in turn reduces the influx of protein from food - a vicious circle arises.

In order to prevent this from happening, it is necessary to constantly introduce physiologically into the body. required amount protein with food.