Protein is the basic building block for all living organisms. There are many types of protein, and each of which has its own purpose and function.
About the functions of proteins
Depending on the function, there is the following classification of proteins:
- Transport. Proteins that carry chemical components through cells.
- Motor function is also carried out at the expense of proteins that contribute to muscle contraction.
- Structural. Provides strength to muscle and cellular tissue.
- Building, that is, the function responsible for the formation of muscle and other tissues.
- Regulatory. These are actually hormonal proteins that are responsible for metabolic processes in the body.
- Energy, that is, proteins periodically act as an energy source.
- Protective. Among proteins, there are antibodies that protect the body from infections.
- Receptor, which allows you to keep mediators and hormones inside the body.
- Signal, that is, providing the transfer of information between tissues, cells and organs.
There are many more functions of protein, including storage, enzymatic, catalytic, and others. Proteins can also have a detoxifying and vice versa toxic effect on the body.
Some information about the structure of proteins
Proteins are actually biological polymers made up of monomers or, more simply, amino acids. The bonds of these acids are carried out using peptides, which form a long chain with proteins.
Amino acids necessarily contain carbon, oxygen, hydrogen and nitrogen.
The role of proteins in the human body
Protein plays one of the main roles in the functioning of the human body. It is one of the components of the immune system, participates in the formation of muscle tissue, is responsible for cell regeneration and metabolic processes. It is the so-called skeleton of the skin, hair and nails.
An interesting fact is that the body generates energy through the breakdown of fats and carbohydrates, but at the same time has a strategic supply of protein. If there is a lack of the first two substances in the body, then energy is generated due to the breakdown of protein. Although this process cannot be lengthy.
Amino acids in proteins
To date, scientists have managed to isolate about 200 amino acids, but only 20 of them are involved in the formation of proteins.
Essential amino acids can be synthesized in the body, but essential ones cannot. Complete and deficient amino acids, simple and complex, are also isolated. Simple – these are proteins that consist exclusively of amino acids.
Essential amino acids of proteins
Of the main nonessential amino acids, the following can be distinguished:
- asparagine, found in dairy products, whole grain breads, walnuts;
- glycine, which is part of cheese, milk, kiwi;
- glutamine, found in cabbage, cottage cheese, some types of cheese, beets and beef;
- alanine, found in veal, bran, hard cheese;
- proline, which can be found in eggs, fish, butter;
- serine, which is part of chicken and egg meat;
- taurine, found in meat and milk, and others.
Partially replaceable acids include gastidine and arginine. They are involved in the production of protein in the body.
Essential amino acids
The human body is not able to produce these acids on its own, therefore it must receive from the outside. They can be present not only in food, but also in medicines and food supplements.
You can find amino acids in the following foods:
- valine, found in hazelnuts, blueberries, soybeans, oranges;
- leucine, found in meat, fish, seeds, olives;
- isoleucine, in sea fish, certain types of grains, almonds;
- methionine, in cocoa, beef, kefir;
- phenylalanine, in spirulina, chicken, beef;
- threonine, in egg white, nuts;
- tryptophan, in yogurt, turkey, milk;
- histidine, in rice, seaweed, melon;
- lysine, in vegetables, fish.
From this list it becomes clear that the body receives protein not only from meat products, but also from plant foods.
What to eat protein foods with
The digestive process requires some effort from the body and a lot of energy. The body fully wakes up after sleep only 4 hours after waking up. For this reason, it is recommended to consume protein foods exactly after this time after sleep.
Protein is better digested with fats. Bad combination – carbohydrates and proteins in one meal. Do not eat potatoes, bread and meat at the same time. The same rule applies to legumes.
Greens and vegetables are best suited for digesting protein. Ideally, these should be sour vegetables, such as spinach, lemon, or sorrel. It is better to chop vegetables coarsely, using only salt and lemon juice.
After consuming proteins, the meal should consist of lighter foods.
Daily protein intake
A person who does not lead an active lifestyle, like most modern people, should consume about 0.75-1.1 g per 1 kg of his weight. But if a person goes in for sports or work is associated with physical activity, then this indicator increases by 2-2.5 times.
For women, the average serving of protein foods should be about 45 g; for men – 55 g. This is about two servings the size of the palm of your hand.
Keep in mind that protein foods include not only meat and fish, but also nuts, legumes, and tofu.
How does a lack of protein affect the body?
Lack of protein in the human body is extremely rare. However, if this happens, then the symptoms are as follows:
- decrease in muscle mass;
- hair loss;
- skin rashes.
Most often, a lack of protein is associated with eating disorders.
What are the pros and cons of proteins (proteins) of animal and plant origin
Proteins are commonly used in sports nutrition and are popular with vegans. It is believed that plant protein is capable of completely replacing animal protein, although scientists have not yet given an unambiguous answer to this question.
Indeed, vegetable protein is very similar to animal protein, but it has a reduced amount of lysine and methionine, but more glycine and arginine.
Benefits of consuming plant-based proteins:
- reducing the risk of developing diabetes mellitus;
- reducing the risk of heart problems;
- prevention of the development of cancer.
However, in order to saturate the body with all the necessary amino acids for the normal functioning of the body, you will have to eat much more vegetable protein, which, in turn, overloads the digestive system. If a person has given up meat and fish dishes, but is engaged in hard physical labor or sports, then he may have problems obtaining the required amount of energy. Vegans often have problems with the absorption of nutrients, vitamins, and the immune system suffers.
And protein mixtures are generally contraindicated in persons with renal failure, obesity.
The benefits of animal protein include:
- fast saturation of the body;
- the body needs a lot of energy to digest protein, therefore, it spends calories at this time;
- the minimum calorie content of this protein;
- removes excess fluid.
However, it can cause constipation if plant foods are absent from the diet. The kidneys are severely affected by a large amount of protein foods, so you will have to drink a lot of water.
Animal proteins are renowned for their abundant amino acid content. They can be found in the following products:
- Meat. These are, first of all, chickens and rabbits, which are richest in protein content. It is also present in sausages, but on condition that they are from natural raw materials, in offal.
- Milk products. To obtain protein, it is better to choose fermented milk products with a reduced fat content.
- Seafood. Most amino acids are found in tuna, salmon and cod.
- Eggs. These are foods with cholesterol, low fat and high protein content.
Ideally, these products are best combined to provide the body with the widest range of amino acids. Animal proteins are assimilated by the human body by 80%.
In various combinations of plant foods, you can make up for the lack of amino acids in the body and diversify the diet well. The main sources of protein include:
- soy, which is the real leader among all herbal products.
Vegetables and fruits can also fall into this category, but they are still not the best source of protein. For example, in spinach it is only 2.9 g per 100 g of vegetable, and in cherries in general 1 g. Vegetable proteins are absorbed by the body from 60 to 80%, depending on the species.
Differences in protein requirements for men and women
Ideally, the diet should be in the following proportion:
- proteins 12%;
- carbohydrates 55% -59%;
- fats 30% -33%.
There is a lot of controversy about how much protein a person needs per day. For example, the US National Institutes of Health speaks of 0.8 g per kg of body weight. In Russia, it is generally accepted that a man should consume from 65 to 117 g, and women should consume less, from 58 to 87 g, depending on weight.
For a person who is engaged in power sports, an increased rate is provided, from 1.2 to 1.4 g.
In general, there is no consensus in the world regarding this issue. But in what all scientists are united: it is necessary to be attached to gender, to a person’s weight and physical activity.
Protein is one of the main building materials of the human body, involved in metabolic processes. Therefore, you do not need to deny yourself the moderate use of meat and fish dishes.