Amino acids are building blocks of proteins. The name derived from the Greek (“proteios”; first-rate and significant) emphasizes the importance of this group of substances: proteins assume a key function in almost all biological processes of the human body as scaffolding substances or in the form of numerous enzymatic systems.
The human body is able to synthesize a wide variety of structural and functional proteins from amino acids. For this protein biosynthesis, the organism has 20 proteinogenic amino acids* at its disposal.
Of these, the body cannot produce nine compounds itself. They are therefore essential (necessary for life) and must be ingested with food.
Semi-essential amino acids can be formed in the body from other amino acids. For example, the synthesis of cysteine is partially possible from the essential amino acid methionine, and tyrosine can be formed from the essential amino acid phenylalanine. Under certain conditions – e.g., age, growth phase, illness, or physical activity – semi-essential amino acids can become essential to the body. In the newborn, for example, arginine, cysteine, histidine and tyrosine are essential amino acids during the first days of life. Amino acids are classified into the following groups:
- Essential (vital) amino acids.
- Semi-essential (conditionally vital) amino acids.
- Non-essential amino acids
Amino acids are not only important as building blocks of proteins, but also serve as starting products of a variety of compounds that perform important metabolic functions in the body. For example, the L-carnitine, which among other things takes a significant task in fat metabolism, is formed from the two essential amino acids lysine and methionine. If the body lacks an amino acid or if an endogenous substance formed from it, such as a hormone, is no longer sufficiently produced, important bodily functions are no longer optimally guaranteed. * Selenocysteine is first formed in the organism and occupies a special position as the 21st proteinogenic amino acid.
