What role do proteins play in the body? Functions of proteins in the human body

Proteins in the human body are the main material for the development and growth of all cells without exception. The most diverse functions of protein in the body are not compensated by other elements, since they contain essential amino acids. The most important role of proteins in the body is that they participate in the replication of DNA and RNA molecules.

The meaning and role of proteins in the body

Life without protein is impossible. The importance of proteins for the body lies in the fact that they serve as material for the construction of cells, tissues and organs, the formation of enzymes, most hormones, hemoglobin and other substances that perform essential functions in the body. Proteins and their role in the body is also that they are involved in protecting the body from infections, and also promotes the absorption of vitamins and minerals. Our life activity is associated with the continuous consumption and renewal of protein. To balance these processes, protein losses must be replenished daily. Unlike fats and carbohydrates, it does not accumulate and is not synthesized in the body from other nutrients, that is, you can only get protein with food.

Protein absorption by the body

The absorption of protein by the body begins in the stomach and continues in the cavity small intestine. Consequently, diseases of the pancreas and small intestine negatively affect this process. Next, you can find out how protein is absorbed in the human body and how it is used.

In turn, with a long-term and severe deficiency of dietary protein, the formation of digestive juices and especially enzymes is disrupted - first in the pancreas, and then in the stomach and small intestine. This leads to diarrhea not associated with intestinal infection.

Where is there a lot of protein in food?

You need to know where a lot of protein is found in order to correctly formulate the composition of your daily diet. Information on the protein content in basic foods is given in the table. From it you can get basic information about where the proteins are in the food on your table.

Table - Protein content in 100 grams of the edible part of products:

Amount of gloss, g	Food products
Very large (more than 15)	Low-fat cottage cheese, animal and poultry meat, most types of fish, seafood, egg white, soybeans, peas, beans, nuts
Large (10-15)	Cheese, full-fat cottage cheese, meat and fatty pork, whole eggs, semolina, buckwheat, oatmeal, millet, wheat flour, pasta
Moderate (5-9.9)	Rye and wheat bread, pearl barley, rice, green peas
Small (2-4.9)	Milk, kefir, cream, sour cream, ice cream, spinach, cauliflower, potatoes
Very small (0.4-1.9)	Butter, almost all vegetables, fruits, berries and mushrooms

50 grams of beef or chicken meat, cottage cheese with a fat content of 4%;
55 grams of horse mackerel, mackerel;
60 grams of cod, hake, carp;
70 grams of pork meat, fatty cottage cheese;
80 grams of whole eggs (two pieces without shells), buckwheat;
85 grams of boiled sausage;
90 grams of sausages, oatmeal, millet, pasta;
100 grams of boiled peas
100 grams of semolina and barley;
125 grams of wheat bread;
140 grams of rice;
200 grams of green peas;
350 grams of milk, sour cream, full-fat kefir;
500 grams of potatoes, white cabbage;
700 grams of carrots;
2.5 kilograms of apples, pears.

Nutritional and biological value of proteins

It is necessary to take into account not only quantity, but also quality - the biological value of proteins, which depends on the content of amino acids in it. In total, proteins can contain over 20 amino acids, but only eight of them are not formed in the body, so they must come from food. Such amino acids are called essential.

In order for food protein to be fully absorbed, amino acids must be present in it in a certain ratio. The lack of even one amino acid can prevent the full participation of all others in the construction of proteins in the body. The nutritional and biological value of proteins is calculated using special tables.

Why does the body need protein?

It has been noted that in the diet of a significant part of the population there is a deficiency of three essential amino acids: lysine, methionine, tryptophan - and a derivative of the latter - serotonin. Many people wonder why the body needs protein. large quantities if there is a process of weight loss. And this is a very dangerous mistake. Animal products are much richer in these substances. Therefore, animal proteins are not only well absorbed, but also significantly improve absorption vegetable proteins, which allows you to balance amino acid composition food during meals. You can’t exclude meat from your diet, even if you really want to lose weight.

Proteins in human nutrition: effects on the body

Biologically valuable proteins in human nutrition, characterized by a balance of amino acids and good digestibility, include proteins from eggs and dairy products, as well as meat and fish, with the exception of connective tissue. The effect of proteins on the human body largely depends on their quality and quantity supplied with food.

Less complete are plant proteins, the amino acid composition of which is not sufficiently balanced. In addition, the proteins of many plant foods are difficult to digest, since they are enclosed in shells of fiber and other substances that interfere with the action digestive enzymes. This especially applies to legumes, mushrooms, nuts, and whole grain cereals. More than 90% of amino acids are absorbed from animal proteins in the small intestine, and from proteins plant origin- only 70-80%.

How much protein does the body absorb?

Calculation of how much protein the body absorbs depends on the quality of the foods consumed and their origin. Animal proteins are absorbed 1.5 times better than proteins of plant origin.

The proteins of dairy products, eggs and fish are digested most quickly, then meat (beef proteins are faster than pork and lamb proteins), bread and cereals, and the proteins of semolina and wheat bread made from premium flour are more active.

From collagen (connective protein, cartilage and bone tissue) produce gelatin, which is used to prepare jelly-like dishes. Gelatin is incomplete in its amino acid composition, but is easily digested. In addition, it stimulates blood clotting. Dishes using gelatin are recommended to be included in the diet of patients who have undergone surgery on the digestive organs. gastrointestinal bleeding, maxillofacial injuries, etc.

Products containing protein

The most balanced amino acid composition of egg proteins, dairy products, meat and fish. These foods that contain protein are also digested faster than other proteins.

Heat treatment accelerates the digestion of proteins, which is confirmed by the example of boiled and raw eggs. Proteins are better absorbed by prolonged boiling or chopping of foods. This is especially true for plant proteins. True, excessive heat can negatively affect amino acids. Thus, the biological value of casein (milk protein contained in cottage cheese) decreases by 50% when heated to a temperature of 200 °C. And with strong and prolonged heating of carbohydrate-rich foods, the amount of lysine available for absorption in them decreases. This explains the recommendation to soak cereals before cooking in order to reduce the cooking time of porridges.

Heat treatment and chopping foods improve protein digestion.

The above once again confirms the opinion that in order to meet the amino acid needs of the body, it is more advisable to combine different products. For example, if there is wheat bread with milk, the total amino acid composition of the protein becomes biologically more valuable than when eating bread without milk. For the same reason, combining cereals with milk or preparing milk cereal soups, milk noodles, etc. is quite justified.

Where is the most protein found?

It is also worth understanding where the most protein is found in plant-based foods. The most valuable plant proteins are found in buckwheat, legumes, potatoes, rice and rye bread.

Comparatively beneficial in this regard flour products with cottage cheese (vareniki, sochniki) or meat (dumplings, meat pies, etc.), while the combination of dough with rice and other cereals is less justified.

The biological value of proteins increases with a combination of grains, legumes and meat and dairy products. To increase the protein content of nutrition, bakery products enriched with skim milk or whey, egg and milk pasta. There are also special dry concentrates with high content easily digestible proteins used to feed seriously ill patients.

However, in some cases it becomes necessary to limit protein intake, for example, in case of kidney or liver failure. For this purpose, special low-protein cereals, pasta and bakery products are used.

How much protein should a person consume per day?

Protein is an absolutely irreplaceable part of nutrition. No matter how you rearrange your diet, never significantly reduce the amount of protein: your body needs it. Next, we’ll look at how much protein a person needs to fully meet their daily needs.

At every meal, try to combine less valuable plant proteins (bread, cereal, pasta) with animal proteins (milk, cottage cheese, cheese, meat, fish, eggs).

How much protein is needed per day can be calculated according to established sanitary standards. According to modern Russian standards for those not involved in physical labor and sports healthy men and women aged 18-29 years, the protein requirement is on average 1 grams per 1 kilogram of normal body weight for a given person. In this case, the share of animal proteins should be at least 55% of the total amount of protein. Some consider these recommendations to be too high. But there is no doubt that in the diet of people who have undergone extensive surgical interventions or serious injuries, with burn disease, bone fractures, diseases of the digestive system (such as chronic enteritis and pancreatitis, conditions after resection of the small intestine and stomach, etc.) , suppurative lung diseases, active tuberculosis, malignant tumors, blood loss, taking corticosteroid and anabolic hormones, etc., as well as for patients recovering from severe infections, animal protein consumption can be increased to 55-60%. However, even in these cases, the amount of protein entering the body, as a rule, should not exceed 120-130 grams per day. How much protein you should consume depends on your lifestyle, physical activity, health status and many other factors.

Proteins in the body perform the function

Proteins in the body perform the function of recovery during chronic inflammatory processes. Protein consumption is limited in case of liver and kidney failure, gout and some other diseases. Thus, in low-protein diets prescribed for chronic renal failure, its content should be only 20-40 grams, of which 65-70% can be of animal origin. In some cases, it is even possible to temporarily exclude protein from the diet.

Lack of protein in the body

A lack of protein in the body is observed with a long-term imbalance between the intake and breakdown of protein in the body, when the breakdown process begins to predominate. Its reason lies in low protein intake from food or in the predominant consumption of low protein biological value, which are characterized by a deficiency of essential amino acids. At the same time, the diet can satisfy the body's need for energy through carbohydrates and fats. However, energy deficiency aggravates the lack of proteins: proteins begin to be spent on the body's energy costs, and the absorption of protein supplied with food deteriorates.

When the principles of rational nutrition are violated, which can be caused by unfavorable socio-economic factors or a passion for physiologically unjustified diets, the so-called nutritional disorder occurs. protein deficiency. But more often protein deficiency is caused by various diseases. Digestion and absorption of protein are often impaired by diseases of the digestive organs, especially the pancreas and intestines. Increased consumption or loss of protein is observed in active tuberculosis, infectious diseases, kidney diseases, severe injuries and operations, extensive burns, malignant neoplasms, massive blood loss, etc.

In case of liver or kidney diseases, excessively long low-protein diets can lead to this condition.

A healthy adult needs to consume about 80-90 grams of protein per day, half of which should come from animal products.

Protein deficiency contributes to the deterioration of the digestive system (especially the liver and pancreas), endocrine, hematopoietic, immune and other body systems, and muscle atrophy. The body begins to absorb others less efficiently nutrients, which leads to the emergence of corresponding deficiency states, for example hypovitaminosis. Performance and resistance to infections decrease, recovery slows down when various diseases, in particular wound healing after operations and injuries.

Excess protein in the body

Excess protein in the body is also harmful, since it causes overload of the liver and kidneys with its breakdown products. Excess animal proteins contribute to the accumulation of uric acid in the body, which serves as a risk factor for the development of kidney stone disease and gout.

Proteins are the most important chemical compounds, without which the life of the body would be impossible. Proteins make up enzymes, organ cells, and tissues. They are responsible for metabolic, transport and many other processes taking place in the human body. Proteins cannot be stored “in reserve”, so they must be regularly supplied to the body. They are of particular importance for people involved in sports, because proteins regulate motor functions of the body, are responsible for the condition of muscles, tendons, and bones.

Proteins are high-molecular complex organic compounds consisting of amino acid residues connected in a special way. Each protein has its own individual sequence of amino acids and its own location in space. It is important to understand that proteins entering the body are not absorbed by the body in an unchanged form; they are broken down into amino acids and with their help the body synthesizes its proteins.

22 amino acids take part in the formation of proteins, 13 of them can be converted into one another, 9 - phenylalanine, tryptophan, lysine, histidine, threonine, leucine, valine, isoleucine, methionine - are essential. Lack of intake into the body essential acids unacceptable, it will lead to disruption of the body’s vital functions.

It is not only the fact that protein enters the body that is important, but also what amino acids it consists of!

Protein biosynthesis is the formation in the body of the necessary proteins from amino acids by connecting them with a special type of chemical bond - a polypeptide chain. DNA stores information about the structure of proteins. The actual synthesis occurs in a special part of the cell called the ribosome. RNA transmits information from the desired gene (part of DNA) to the ribosome.

Since protein biosynthesis is multi-stage, complex, and uses information embedded in the basis of human existence - DNA, its chemical synthesis is a difficult task. Scientists have learned to produce inhibitors of certain enzymes and hormones, but the most important scientific task is to obtain proteins using genetic engineering.

Functions of proteins in the body

The qualification presented is conditional, because often the same protein performs several functions:

Structural

Protein is part of the organelles and cytoplasm of any cell in the human body. Connective tissue proteins are responsible for the condition of hair, nails, skin, blood vessels, and tendons.

Enzymatic function

All enzymes are proteins.
But at the same time, there is experimental data on the existence of ribozymes, i.e. ribonucleic acid with catalytic activity.

Catalytic

Almost all 3,000 enzymes known to mankind are made of protein. Most of them are involved in the processes of breaking down food into simple components, and they are also responsible for delivering energy to cells.

Receptor function

This function is to selectively bind hormones, biologically active substances and mediators on the surface of membranes or inside cells.

Hormonal

Hormones are represented by proteins; they are responsible for regulating complex biochemical reactions of the human body.

Transport

Transport function of a special blood protein - hemoglobin. Thanks to this protein, oxygen is delivered from the lungs to the organs and tissues of the body.

Protective

Consists in the activity of proteins immune system called antibodies. It is antibodies that guard the health of the body, protecting it from bacteria, viruses, poisons, and allow blood to form a clot at the site of an open wound.

The signaling function of proteins is to transmit signals (information) between cells.

Contractive

Any human movement is complex balanced work muscles. Special proteins myosin and actin are responsible for coordinated muscle contraction.

Protein sources: animal and vegetable proteins

Animal protein sources:

fish;
bird;
meat;
milk;
cottage cheese (more details:);
serum;
cheeses;
eggs.

Plant based protein sources:

legumes – soybeans, beans, lentils;
nuts;
potato;
cereals – semolina, millet, pearl barley, buckwheat.

Protein standards for an adult

The human body's need for protein directly depends on its physical activity. The more we move, the faster all biochemical reactions occur in our body. People who exercise regularly require almost twice as much protein as the average person. A lack of protein for people involved in sports is dangerous by “drying out” the muscles and exhausting the entire body!

On average, the protein norm for an adult is calculated based on the coefficient of 1 g of protein per 1 kg of weight, i.e. approximately 80–100 g for men, 55–60 g for women. Male athletes are recommended to increase the amount of protein consumed to 170–200 g per day.

Proper protein nutrition for the body

Proper nutrition to saturate the body with protein consists of a combination of animal and plant proteins. The degree of protein absorption from food depends on its origin and the method of heat treatment.

Thus, the body absorbs approximately 80% of the total intake of animal proteins and 60% of plant proteins. Animal products contain more protein per unit mass of product than plant products. In addition, “animal” products contain all amino acids, and plant products in this regard are considered inferior.

Basic nutritional rules for better protein absorption:

A gentle cooking method is boiling, steaming, stewing. Frying should be excluded.
It is recommended to eat more fish and poultry. If you really want meat, choose beef.
Broths should be excluded from the diet; they are fatty and harmful. IN as a last resort you can prepare the first course using “secondary broth”.

Features of protein nutrition for muscle growth

Athletes actively gaining muscle mass should adhere to all of the above recommendations. The majority of their diet should consist of animal proteins. They should be eaten together with plant protein products, of which soy should be given special preference.

You should also consult your doctor and consider drinking special protein drinks, the percentage of protein absorption of which is 97–98%. The specialist will individually select the drink and calculate the correct dosage. This will be a pleasant and healthy protein addition to your strength training.

Features of protein nutrition for those who want to lose weight

Those who want to lose weight should eat animal and plant protein products. It is important to separate their intake, because their absorption time is different. You should avoid fatty foods meat products, you should not overuse potatoes; you should give preference to cereals with an average protein content.

You shouldn’t go to extremes and “go on” a protein diet. It is not suitable for everyone, because completely eliminating carbohydrates will lead to a decrease in performance and energy. It is enough to eat foods containing carbohydrates in the morning - this will give you energy throughout the day; in the afternoon, eat protein-based, low-fat foods. To make up for the lack of energy in the evening, the body will begin to burn body fat, at the same time, this process will be safe for the health of the body.

Be sure to include the right and properly prepared protein foods in your diet. Protein is the main building material for the body! Together with regular training, it will help you build a beautiful athletic body!

The main thing is not the design of the house, but what it is built from! If the material is strong and moisture-resistant, then the house will serve you for a long time and will not cause much trouble, but if the material is of poor quality, expect a lot of breakdowns and lengthy repairs. Proteins are the main building material for the human body. The biological role of proteins is inestimable. Every cell of the human body consists of 50% of them. They are the structural elements of bones, skin and hair. Without them, biochemical reactions do not start, hormones and enzymes are not produced.

In turn, proteins in the body are made up of amino acids. Amino acids are arranged one after another, like beads in a necklace. In this case, a long chain is formed, in which the amino acids are in strict sequence. Their location is determined by biological and Chemical properties squirrel. Amino acids are divided into two groups: essential and non-essential. Essential amino acids are not produced in the human body. They must mandatory enter the body from food. Nonessential amino acids are made using other amino acids. To understand the importance of proteins for the body, let's consider what functions they perform.

Functions of proteins in the body

Proteins protect against disease. They fight viruses, fungi, bacteria and toxins. They participate in blood clotting, protecting a person from excessive blood loss.

Regulate hormonal levels. Hormones in our body are made up of proteins. If your glands get raw Low quality, this affects their functioning.

Helps digest food. Enzymes in the body that are involved in digestion are proteins. The popular expression “I have a stomachache” only indicates the lack of the necessary building material in the body.

Saturate the body with oxygen. In the blood, hemoglobin, which consists of protein and iron, is responsible for the transport of oxygen. Even if you eat the product with high content iron, but do not replenish protein, hemoglobin will not increase. Oxygen, in turn, is a powerful blood purifier and acts as an oxidizing agent; it burns toxins to ensure their removal from the cell. Hemoglobin also supplies oxygen to the brain, keeping your thoughts fresh.

Proteins help increase muscle mass. These nanometer-sized particles in the body form the basis of muscle tissue, speed up resting metabolism, and also block the feeling of hunger.

They are the ones who protect you from premature aging. Keratin and collagen are protein compounds that are part of the epidermis and are responsible for its strength, firmness, smoothness and elasticity.

The role of proteins in the human body is invaluable. An insufficient amount of them leads to disturbances in the functioning of the body. The liver, pancreas and endocrine system. In addition, the metabolism and absorption of vitamins is disrupted, muscle atrophy is observed, memory deteriorates and chronic fatigue. This has a particularly detrimental effect on the development of the child, which is manifested by slower growth and brittle bones. The following symptoms may also occur:

sudden weight loss,
hair loss and dullness,
pale, dry and flaky skin,
swelling,
unevenness on the nails,
weakness and apathy,
slow healing of wounds.

But too much protein can also cause harm. It is not able to stay in the body. The excess protein is converted by the liver into white crystals called urea, which the kidneys are forced to remove. An excess amount of protein creates an acidic environment in the body, which leads to increased calcium loss. But in human life it is very rare to find an excess of proteins in the body; more often there is a lack of them.

Consumption rate

Depending on the composition of amino acids in proteins, complete and incomplete proteins are distinguished. Until recently, it was believed that incomplete proteins were found in plant foods such as beans, bread, and nuts. And only meat, fish, dairy products, and eggs were considered. But recent studies refute this fact; the fact is that by supplementing the proteins of one plant product proteins of another, we can easily obtain the necessary set of amino acids.

Proteins that come from food are not ideal for absorption, which means that not all the protein is used for their synthesis. Therefore, nutritionists recommend combining some foods with each other. For example, a combination of whole grains and legumes is more beneficial. Heat treatment also helps better absorption squirrel. However, the temperature should be low when cooking vegetable protein.

The role of proteins in the human body is fully realized if a certain rate of their consumption is observed. For a healthy person’s diet, 1 g of protein per 1 kg of body weight is required. For children, pregnant women and people actively involved in sports, this number increases to 1.5-2 grams. Each main meal should contain 30% of the proteins daily value and 5% for a snack.

100 g soy – 39 g protein,
100 g pumpkin seeds– 30 g,
100 g potatoes – 2 g,
100 g – 5 g.

It is also important to follow the rules for their preparation. Do not cook the product at a very high temperature; it is better to prolong this process. Legumes should be soaked for a while and only then boiled. If you follow certain cooking rules, proteins will be better absorbed by the body.

Vegetable protein and animal protein

Animal protein is found in animal products such as meat, fish, eggs and dairy products. Often a person prefers these products, but they are fraught with danger. Too much has an unfavorable effect on the body, so it’s worth diversifying your daily diet with foods containing plant protein.

It is represented by products of four groups:

legumes (peas, chickpeas, lentils, beans, soybeans and others),
grain crops (wheat, barley, pearl barley, millet, buckwheat),
nuts and seeds (almonds, peanuts, cashews, sunflower and pumpkin seeds),
vegetables (cabbage, garlic, potatoes, beets, spinach).

Medicine knows that people who prefer animals to animals are less likely to get sick in their lives. oncological diseases, are less prone to obesity and diabetes mellitus. Plant proteins keep you full longer, which helps you avoid overeating throughout the day.

Rules for eating protein foods

Start your day with a protein-rich breakfast. This will make you feel full and you won't be hungry any time soon. Known fact: in the first half of the day, proteins are absorbed better.

Combine protein foods. Dilute your diet with plant-based protein foods.

Divide your protein portions throughout the day. It will be difficult for the body to absorb all daily norm squirrel at a time.

If you lead an active lifestyle, a portion of protein 30 minutes after training will help you get into ideal shape.

Determine your protein intake and stick to it strictly. An amount of protein higher than normal can cause poisoning.

Combine foods correctly. For example, spirulina algae is well compatible with vegetables that are rich in starch. Vegetables and herbs will be an excellent addition. Legumes go perfectly with herbs and cereals.

Cook protein foods at low temperatures, cook them longer, and pre-soak legumes.

Protein requires a lot of water to digest. Drink enough of it: As a rule, it is recommended to drink eight glasses of water a day.

Maintain the proportion of proteins in your diet with fats and carbohydrates, adhere to the above rules. Then you will feel a surge of strength and health, and also destroy excess weight. Good luck on your path to a healthy life!

Proteins, like vitamins and other nutrients, are an integral part of the healthy functioning of our body.

Most of our diseases are associated with poor nutrition, in particular with high consumption of proteins. Experts never tire of repeating that our body needs balanced diet. Excluding some product from our diet can lead to microelements, which in turn leads to disruption of the body.

Most often people underestimate the role proper nutrition in the functioning of our body. According to a sociological survey, it became known that 50% (of those surveyed) do nothing to maintain their health.

Proteins play an important role in the formation of tissues (organs, muscles, etc.), they are needed for the synthesis of hormones, and are also necessary for the formation of enzymes. The transmission of necessary information from one cell to another through the nervous system is also associated with proteins. Proteins help in the process of blood clotting, DNA represents protein molecules, and proteins also participate in the body’s energy processes (1g of protein produces 4 kcal of energy).

From this we can conclude that proteins are involved (directly or indirectly) in most of the processes that occur in our body. If there is a lack of proteins in the body, then all of the above processes will suffer.

Process of protein digestion happens at different speeds. Proteins obtained by the body from fish or dairy products are digested the fastest, followed by proteins obtained from meat products. Proteins of plant origin are digested more slowly.

What proteins should you give preference to? Nutritionists say that to maintain normal functioning organism in the menu must be included 30% plant proteins and 70% animal proteins. These data should be changed only if you have any pathology: for example, in case of kidney pathology, preference should be given to proteins of plant origin.

An important role in required quantity The surrounding climate also plays a role in protein factors. For example, vegetarians from Asia are quite healthy when daily use 30-40g of protein, while Eskimos consume 200-300g of protein.

According to its chemical composition proteins can be divided into complete and incomplete. To determine the usefulness of proteins, the presence of essential amino acids is considered, since it can synthesize all the rest itself. Complete proteins contain all the essential amino acids in the quantities needed by the body.

Animal proteins have a full set of essential amino acids (meat, fish, eggs and milk).

Plant based proteins are considered incomplete, with the exception of legumes. Beans contain the same amount of proteins as animal products.

For the full functioning of the body proteins of animal origin are necessary, as they are absorbed by 94-97%. However, this does not mean that you should not include plant proteins in your menu. For full growth and development of the body, a balance between animal and plant proteins is necessary.