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Essential amino acids and their tasks

Amino acids play a vital role in our body. As proteinogenic amino acids, they are primarily involved in the formation of proteins. They are also required for numerous metabolic processes in the body, for example for the formation of antibodies or enzymes and for the synthesis of hormones and neurotransmitters. There are 21 proteinogenic amino acids, which are divided into essential and non-essential.

Essential amino acids (EAA for short)

An amino acid that the body needs to survive but cannot produce itself is referred to as essential. Such amino acids must be supplied through food or supplements.

There are eight essential amino acids in total. These include leucine, isoleucine, valine, phenylalanine, tryptophan, methionine, threonine and lysine. However, there are also amino acids that cannot be provided or cannot be provided in sufficient quantities in certain situations, e.g. in the case of various illnesses, enzyme defects, during growth and during high levels of physical activity. These amino acids are referred to as semi-essential and include the amino acids arginine, cysteine, tyrosine, glutamine, serine and histidine. However, histidine is only essential in infants and young children.

All other amino acids can be formed under normal conditions and with sufficient nitrogen.

Interesting to know: Strictly speaking, only threonine and lysine are absolutely essential, as the other amino acids can be transaminated from their corresponding keto acids. In the case of threonine and lysine, transamination is irreversible (= irreversible).

BCAA - leucine, isoleucine and valine

The three amino acids leucine, isoleucine and valine are branched-chain amino acids (BCAAs). In contrast to the other amino acids, which are primarily metabolized in the liver, our body breaks down the BCAAs directly in the muscle. They are therefore primarily involved in building muscle, so they have an anabolic (anabolic) effect and serve as a source of energy for the muscle cells.

Various studies also show that regeneration after training can be improved by supplementing with branched-chain amino acids, resulting in less muscle damage and muscle soreness. You can find out more about BCAA and muscle soreness in our blog post.

BCAAs also stimulate the release of insulin. This regulates blood sugar levels and accelerates the absorption of amino acids into the muscles and liver.

You can find our BCAA powder here.


Phenylalanine is the precursor of the amino acid tyrosine. If sufficient amounts of phenylalanine are present, tyrosine can be formed in the liver. However, if the amount is not sufficient, tyrosine must also be taken in with food. One example of this is the metabolic disorder phenylketonuria. In this case, the conversion of phenylalanine to tyrosine is impaired. Tyrosine becomes an essential amino acid.

Phenylalanine is involved in the synthesis of various hormones such as adrenaline, noradrenaline and the neurotransmitter dopamine. It is also important for the formation of the two thyroid hormones triiodothyronine (T3) and thyroxine (T4). The pigment of the skin, melanin, is also formed from phenylalanine. This is found in the skin, hair and in the choroid and iris of the eye.


Tryptophan is primarily a precursor of serotonin, a neurotransmitter also known as the "happiness hormone". Serotonin is said to influence our mood by promoting feelings such as contentment and balance. It also has a calming effect and stimulates memory. As serotonin is converted into melatonin in the brain, tryptophan also has an indirect positive influence on our sleep.

Tryptophan is also important for the formation of niacin (vitamin B3) in the body. You can find important information about niacin here.


Together with cysteine, methionine is the main source of sulphur in the human diet. It is required for the formation of the amino acid cysteine, but not vice versa. Methionine is therefore essential and cysteine is conditionally essential.

Methionine is involved in numerous metabolic processes, as it releases a specific chemical compound (methyl group) to other substances. For example, to carnitine, creatine and taurine, which are particularly relevant in sport.

Selenium metabolism is also methionine-dependent, which means that methionine is involved in the absorption of the trace element selenium. Selenium is also present in our selenium supplement in the compound selenomethionine.


Lysine is primarily important for the production of collagen and elastin. As connective tissue is made up of collagen and elastic fibers, lysine is important for strengthening connective tissue. This is because cellulite, spider veins, stretch marks and varicose veins can only be prevented if sufficient supporting collagen fibers are formed. You can find out everything else about strengthening connective tissue and lysine in the following blog post.

The amino acid not only plays an important role in collagen synthesis, but also has a crucial function within the immune system. Supplementation of lysine is said to have a positive effect on a herpes infection. Read more about this here.

Lysine is also of particular importance as a precursor of carnitine.


Like lysine, threonine is often found in the collagen of connective tissue and is therefore important for the substance of bones, teeth, tendons and ligaments.

Threonine is also important for the production of antibodies and immunoglobulins, which are essential for a good immune defense. Threonine is also found in the mucous substances (mucins) in our body. Mucins protect the stomach from strong acids, for example.

What is the best way to memorize the essential amino acids now? Would you like to remember the essential amino acids more easily? Then we have a little mnemonic for you:

Phenomenal Isolde clouds Lieutenant Valentin's lustful dreams.

  • Phenylalanine
  • Isoleucine
  • Tryptophan
  • Methionine
  • Leucine
  • Valine
  • Lysine
  • Threonine
Or even simpler: PheTTVILLM (pronounced: fat film)

P.S.: Maybe you're unsure whether you should supplement with BCAA or EAA? No problem, we have the answer in the following blog post.

Sources: Biesalski H. K. and Grimm P. (2007) Pocket atlas of nutrition. Thieme Verlag, 4th edition, Stuttgart. Heinrich P. C., Mueller M. and Graeve L. (2014) Löffler/Petrides Biochemistry and Pathobiochemistry. Springer-Verlag, 9th edition, Berlin Heidelberg.