Amino acids are organic acids, the molecules of which contain one or more amino groups (NH2 groups). They represent the basic structural elements of proteins. Proteins of food in the human body are split up into amino acids. A certain part of the amino acids, in turn, is split up to organic keto acids, from which new amino acids are synthesized in the body, and then new proteins are synthesized. In human body, 20 amino acids that perform proteins have been found.


Amino acids are absorbed from the gastrointestinal tract and with the bloodstream enter into all organs and tissues, where they are used for the synthesis of proteins and undergo various transformations. A constant concentration of amino acids is maintained in the blood. About 1 g of nitrogen of amino acids per day is excreted from the body. In muscles, brain tissue and liver, the content of free amino acids is many times higher than in blood, and is less permanently. The concentration of amino acids in the blood allows to judge about the functional state of the liver and kidneys. The content of amino acids in the blood can significantly increase with violations of kidney function, fever, diseases associated with high protein content.


Amino acids are classified as essential (valine, leucine, isoleucine, threonine, methionine, phenylalanine, tryptophan, lysine), conditionally essential (arginine and histidine) and nonessential (alanine, asparagine, aspartic acid, glycine, glutamine, glutamic acid, proline, serine, tyrosine, cysteine).


Essential amino acids are not synthesized in the human body, but are necessary for normal vital activity. They have to enter the body with food. With a deficiency of essential amino acids, growth and development of the body are delayed. The optimal content of essential amino acids in the dietary protein depends on the age, gender and profession of the person, as well as on other reasons. Nonessential amino acids are synthesized in the human body.


Amino acids are structural chemical units that form proteins.


Any living body consists of proteins. A variety of forms of proteins are involved in all processes occurring in living organisms. In the human body, proteins, muscles, ligaments, tendons, all organs and glands, hair, nails are formed from proteins; proteins are a part of liquids and bones. Enzymes and hormones that catalyze and regulate all processes in the body are also proteins.


Deficiency of proteins in the body can lead to a violation of the water balance, which causes swelling. Each protein in the body is unique and exists for special purposes. Proteins are not interchangeable. They are synthesized in the body from amino acids, which are formed as a result of the splitting of proteins found in food. Thus, it is the amino acids, and not the proteins themselves, which are the most valuable elements of nutrition.