Amino acids, protein links

Proteins are continuously formed and destroyed inside cells, and thanks to this, living things have the capacity for growth, repair and regulation. Their presence in living beings is essential for the development of several vital processes.

All proteins, regardless of the function they perform, are formed by a basic group of 20 amino acids arranged in various specific sequences. Proteins are formed by an average of 400 amino acids, although some have a complex structure that may contain thousands of amino acids and the smaller ones may contain only 50. Amino acids are linked together by peptide bonds.

How do we classify amino acids?

Amino acids can be classified in several ways. An important classification is the nutritional one, dividing them into essential and non-essential amino acids depending on whether the diet must provide them or not.

• Essential amino acids are the ones that the body cannot synthesize and thus must be provided by the diet. If we lack one of these essential amino acids, we will not be able to synthesize any of the proteins for which this amino acid is necessary. This may lead to different disorders, depending on which amino acid is missing.

• Non-essential amino acids are also important and necessary for the formation of proteins, but the body can synthesize them in the cells, and they do not need to be provided by the diet.

• Conditionally essential amino acids can be synthesized by the body but are not synthesized in sufficient amounts to cover the organic needs, and in certain conditions (during growth, in the recovery of severe injuries, after surgery, etc.), they may be essential.

How can we get amino acids?

Amino acids can be found in protein foods such as meat, fish, eggs, dairy products, legumes, cereals and nuts. A protein is complete when it contains all the essential amino acids in sufficient quantity and adequate proportion for the proper development and functioning of the body. These proteins are found in foods of animal origin and in soy, and among them, eggs are considered the best-quality protein. Legumes and cereals separately usually lack some essential amino acids, but if combined, we can get excellent-quality proteins.

Our body does not have an important reserve of free amino acids as such but as part of cellular proteins. There is a constant exchange of amino acids, which maintains a dynamic balance of amino acids in the different parts of the body. This way, if a particular tissue needs proteins, it can synthesize them from the amino acids in blood, which are in turn replenished by the decomposition of cellular proteins, mainly hepatic, and the proteins of other organs or tissues such as kidneys or the intestinal mucosa.

Every type of cell has a limit for storing proteins. When this limit is reached, the excess amino acids are degraded into other products and used to get energy, or transformed and stored as glycogen or fat.

Apart from the 20 amino acids found in proteins, there are about 150 others that only occur in free or combined forms but never in proteins. They are found in different cells and tissues, where they work as precursors or intermediates in metabolism.

Besides protein formation, every amino acid has other specific functions in the body. This means that amino acid supplements, either alone or properly combined with other nutrients, may be an option to improve certain disorders in the body.

Some of the most common indications for these supplements are:

- Improvement of mental and physical performance.

- Skin, nails and hair.

- Reinforcement of defenses.

- Helpful in athletes to increase endurance and promote recovery.

- Helpful in fat burning and to lose weight.

- Mood improvement.

- Complement in degenerative diseases.

- Anxiety and nervousness.