Proteins are essential nutrients with a pronounced structural and functional purpose in every cell of the body. Proteins play a huge role in maintaining vital functions in human health. Moreover, after water, they are the most common chemical components of the human body. All cells in the body contain proteins.
Some of the most important factors in human physiology are proteins. For example enzymes (without which there would be no metabolic reactions), the hormone insulin is a protein, hemoglobin that “carries” oxygen is a protein, immune system globulins (immunoglobulins) are also proteins… With this example, it is quite clear that the importance of protein in the diet far exceeds the frequent connotation of the need for protein solely to build muscle mass.
The most biologically valuable are proteins from food of animal origin: egg white, meat, milk and dairy products, fish. But the diet also needs proteins of plant origin contained in legumes, cereals and nuts.
Proteins are very characteristic and their characteristics are determined by the number and sequence of amino acids in the chain. They are the basic building blocks of every, even the smallest part of our body. They are part of the protoplasm of every living cell and are involved in important biochemical processes in cells.
Neither carbohydrates nor fats can build and renew the organism, but only proteins that need to be taken in through the diet on a daily basis.
Also read: Why it is important to eat breakfast
The most important purpose of proteins in the body
- building and rebuilding muscle tissue and cells of the body
- hair growth, growth of nails, skin
- building hormones that “direct” all bodily functions
- construction of enzymes without which there is no activity (decomposition of organic matter)
- improving the immune system, i.e. making antibodies that protect the body from disease
- restoration of oxygen-carrying hemoglobin
- transport of nutrients through the blood into the cell
- maintaining the acid-base balance in the blood and the normal distribution of water in the body
- they are a source of energy when there are not enough other energy sources in the body (carbohydrates and fats)
Proteins are made up of hundreds of thousands of smaller units. These units are known as amino acids, and are linked to each other by long “chains.”
There are about 20 different types of amino acids. They can build a million different types of proteins, each of which performs a different function in the body.
The order of amino acids in a chain determines the biological character of protein molecules. Protein molecules are large and often contain hundreds of amino acids.
Proteins are extremely complex compounds that occur in a large number of forms and compounds. For example, they can bind to complexes with metals (metalloproteins, such as hemoglobin from the blood) or lipids (lipoproteins, such as HDL or LDL cholesterol).
The theory of evolution puts a leading role in the development of species, stating that the selection of proteins and their functions actually created the perfection necessary for natural selection. The evolution and alteration of proteins are closely related to mutations and changes in DNA, which is the archive of designs for making proteins. Each cell produces specific proteins that determine its role, and form tissues, thus ensuring the polyvalence and efficiency of the functions of an organism.
The purpose of proteins in the body
Precisely because of their great structural diversity, proteins have numerous and different functions in the body. One of the classes of proteins are enzymes. They are crucial for catalyzing countless biological biochemical reactions in plants, animals and other living species. Thus proteins as enzymes accelerate biological processes, control them, or stop them.
Another class of proteins are membrane proteins, which are located in the cell membrane. They form membrane channels or pumps. They have a regulatory function, and control the flow of ions and small molecules into the cell or exit from the cell.
A special class of proteins has a recognizable role in the immune system, and these are antibodies. Their role is to recognize and destroy foreign bodies or antigens. Each cell on the membrane has proteins that serve for recognition. Thus, for example, the immune system distinguishes a virus that enters the bloodstream from its own blood cells.
That proteins build muscle is a well-known fact, but also a big controversy over where to get protein to build and maintain muscle. They come from plant or animal sources. Thus, proteins are becoming an important sociological issue, and today, thanks to the influence of GMO organisms, it is also a political issue.
Proteins can get into our body in different ways, but mainly it is nutrition. With or without supplements. Either way, protein-rich foods are the best source of the same, as the very name of such foods suggests.
Every athlete knows that such foods include animal meat, fish, eggs, milk, and basically all animal products to have a fit body. However, there are certain plants and plant products that have an even higher amount of protein in them. For example, peanuts in 100 grams have up to 25 grams of active protein.
Proteins are not static, they break down and rebuild at every moment in each of our cells. It is important to know how to get enough protein in your daily diet. This should be neither too much nor too little in order to maintain a balance between decommissioning and construction.
Meal distribution and balancing
In the diet, the division of proteins according to their amino acid composition is important.
Essential amino acids are amino acids that the body is not able to synthesize (itself create) from any substance, but must take them in through food. Any lack of essential amino acids means that proteins cannot be fully built up in the amounts needed to build the body. Of the 20 amino acids, eight (for children ten) are essential.
The rest of the amino acids, the body can produce itself if it gets enough nutrients. That’s why we call them non-essential amino acids.
Foods of animal origin, such as milk and dairy products, all types of meat, poultry and fish, and eggs contain all the essential amino acids. That is why we call them complete proteins or high-quality proteins.
According to their composition, foods of plant origin are incomplete proteins and do not contain all the essential amino acids. They need to be properly combined with each other. The most important sources of plant proteins are legumes (soy, beans, lentils, peas), cereals (rice, wheat) and nuts (hazelnuts, almonds and walnuts), while green vegetables and fruits are low in protein.
Plan meals by combining foods of plant and animal origin. For example milk and cereals, meat and rice, eggs and legumes, pasta and cheese… Furthermore, with foods of plant origin, combine cereals with legumes. Eg. rice and peas, nuts and legumes, corn and beans, pasta and beans, soy and seeds, chickpeas and sesame. This will achieve the optimal amino acid composition.
Can I eat too much protein?
Whether you are an athlete or not, proteins play a big role in your body. However, as with everything, we should not overdo it. Although no case of protein overdose or any negative consequences that can occur if you ingest too much protein is known so far, there are other substances in food that should not be found in your body in excessive amounts.
So for example if you ingest excessive amounts of milk, which is otherwise very rich in protein, you will not suffer any negative consequences due to a large dose of protein, but due to a lack of balance in vitamins in your body. Because of all the above, it is necessary for your diet to be balanced and stable. It should be rich in protein, but also all the other vitamins and minerals needed for proper functioning.
Protein reduces appetite and reduces the feeling of hunger
Of all the three macronutrients (fats, carbohydrates and proteins), as research shows, protein has the greatest power to saturate the body and prolong the feeling of satiety. This is partly because protein reduces the level of secretion of the hormone ghrelin, which we call “hunger hormone”. At the same time it also accelerates the secretion of hormones that produce a feeling of satiety in the body. That is why a diet rich in high protein content is suitable for everyone who wants to reduce body weight.
A protein-rich diet also reduces cravings for late meals. The craving for food, especially in the late evening, is not the same as real hunger and the body’s need for nutrients. However, you certainly know for yourself how difficult the craving for food can be. The best way to avoid it is to act preventively so that it does not appear.
A healthy dinner based on protein-rich foods will definitely help. Interestingly, research has shown that a healthy breakfast, which is based on protein, also reduces the appearance of cravings for food and late, evening meals. So we can say proteins even find a big purpose in weight loss.
Why is nitrogen balance important?
In order to be able to synthesize its own proteins, the body needs nitrogen that can be obtained neither from fats nor from carbohydrates, but only from proteins.
A healthy person has a nitrogen balance. Nitrogen excretion is the same as its intake. In other words, the protein ingested with food meets all needs so the body builds new cells and tissues.
When the nitrogen balance is negative (the share of excreted nitrogen is higher than the intake), then the body loses weight and there is a decrease in strength and work capacity. Being able to use your own tissue is important for survival in conditions where food does not provide enough protein, but if such a condition persists for a long time, it becomes life-threatening.
People cannot store excess protein, but they are burned and converted into energy or stored in the form of glycogen or fat, so they should be taken daily.
When the nitrogen balance is positive (the share of excreted nitrogen is less than the intake), then the body must metabolize the excess protein.
What does the label BV (biological value of proteins) mean?
BV (biological value of proteins) is a measure of protein utilization, i.e. the ability of the ingested protein to be fully converted into tissue protein after digestion. It depends on the content of essential amino acids. The more similar amino acids are to the proteins of the human body, the higher their biological value.
BV 100% means that such proteins are almost completely utilized in the body after digestion.
Maximum BV (BV close to 100%), have whey proteins and breast milk, egg proteins (BV close to 100%) and beef proteins (BV 80%), followed by caseinate (BV about 80%), soy protein (BV 70%), wheat flour protein (BV 50%).
BV of plant proteins are lower because plant proteins are deficient with some essential amino acids or have them in insufficient quantities.
Guidelines for a healthy diet
- The energy content of proteins in the meal structure of adults should be about 12% and for children and athletes about 15% to 20% of the total energy intake.
- The daily protein requirement for an adult is about 0.8 grams of protein/kg body weight.
- Daily needs for children and young people during intensive growth are about 1 – 1.5 grams of protein/kg body weight and for infants about 2 grams of protein/kg body weight.
- The amount of protein does not exceed 30 grams in one meal because the body can no longer use it. This means that the daily amount of protein required must be divided into several protein-rich meals.
- The intake of proteins of plant origin should be increased, in the ratio of 2/3 vegetable to 1/3 proteins of animal origin, because too much animal protein in the body also introduces unwanted substances, such as cholesterol and fats.
- When choosing meat, give preference to poultry meat (chicken, turkey) due to the quality of protein, low energy value and lower cholesterol content, and only occasionally consume pork, veal, beef, beef.
- In meals, combinations should be planned – vegetable and animal proteins or legumes and cereals. Chicken, turkey, tuna, pork, beef, sardines, ham, sausages, hot dogs, eggs, cheese, sunflower and sesame seeds, hazelnuts, soy, dry legumes have a protein content between 8 and 32%.
- Care should be taken not to destroy proteins by improper heat treatment and thus reduce their usefulness in the body. Excessively high temperatures reduce protein utilization by up to 80% over time.