What are essential amino acids and why should we take them?

Do you play sports?


Víctor Blasco, PhD in Chemistry. Specialist in Medicinal Chemistry.

We have all heard about the importance of amino acids, as they are essential molecules for the correct functioning of our organism. Due to their enormous biological value, it is interesting to know in greater detail some aspects related to these elementary molecules.

There are a multitude of amino acids, but only 20 are essential for the formation of proteins. These combine with each other to form these biomolecules, which are responsible for regulating the growth, repair, proper functioning and structure of all living cells. Examples are enzymes and antibodies, fundamental proteins involved in chemical reactions in the body and in the immune system.

The 20 amino acids are generally classified into essential and non-essential amino acids. Essential amino acids are those that cannot be produced by the body and therefore must be acquired through food. Non-essential amino acids include those that the body is able to synthesise itself and therefore there is usually no appreciable deficiency.

Eight essential amino acids are known, including valine, leucine, isoleucine, lysine, threonine, tryptophan, phenylalanine and methionine. However, histidine can also be considered as an essential amino acid, especially in infant growth stages, where the body cannot synthesise the full amount required.

The importance of essential amino acids lies in their function. In general terms, they facilitate the breakdown of food, are a source of energy, promote muscle maintenance and gain, and participate in tissue repair and growth, among others. For this reason, this type of amino acid is commonly used as a dietary supplement in sports, and in many cases is considered necessary due to the extra requirements demanded by our body when carrying out physical activity.

In relation to the above, it is possible to highlight the action of branched-chain amino acids, including valine, leucine and isoleucine. These essential amino acids promote the growth of muscle mass, help muscle and tissue regeneration, repair damage and promote protein synthesis. They also help to activate cellular metabolism so that the body begins to build muscle via the mTOR pathway. [1]

These amino acids contribute to improving sports efficiency and performance and also help to prevent both physical and mental fatigue. [2] [3]

Another essential amino acid that has caught our attention is phenylalanine. It has neurotransmitter functions, is capable of keeping the brain active and is an ideal amino acid for stimulating learning and memory processes. [4] It also regulates people’s moods, as it is a precursor of certain hormones such as epinephrine, norepinephrine and dopamine, which is why its intake is recommended for the treatment of illnesses such as depression and anxiety. [5]

At the same time, it is a precursor of tyrosine, which is related both to the synthesis of neurotransmitters and to the regulation of the thyroid gland through the hormone thyroxine. Apart from this, it helps to maintain strict appetite control.

The next amino acid is tryptophan. This is also responsible for regulating appetite, and allows a controlled food intake. On the other hand, it is a good sleep inducer as it is involved in the synthesis of melatonin, a hormone responsible for regulating sleep-wake cycles. As it is also involved in the synthesis of serotonin, it helps to reduce stress and is used in the treatment of anxiety and depression. It is also involved in the production of niacin (vitamin B3), which is necessary for energy production and to keep the nervous system fit. [6]

Another essential amino acid with major health benefits is lysine. This compound regulates the absorption and distribution of calcium in the body, leading some authors to suggest that it may help prevent bone fragility and some osteoporosis problems. [7] It also maintains a good state of connective tissues (cartilage) and is essential for the formation of collagen. It is also considered an essential amino acid for the production of carnitine, which is responsible for energy production inside the cell.

The next amino acid is methionine. Due to its high sulphur content, it helps to maintain healthy nails, skin and hair. It is also essential for the synthesis of cysteine; almost 80% of methionine is used in the synthesis of this protein. It also acts as a precursor in the synthesis of taurine and carnitine, thus contributing to metabolism and fat mobilisation. Finally, this amino acid also contributes to regulating both metabolic processes and the immune system. [8]

Another of these amino acids is threonine. It acts by metabolising fats in adipose tissue, as does methionine, so it helps the liver to function properly, preventing fat accumulation. It also promotes the synthesis of digestive enzymes and immune system proteins, which facilitates digestion and boosts the immune system. Finally, it also promotes muscle growth and recovery by converting to glycine after its breakdown. [9]

Finally, there is histidine. This semi-essential amino acid is a precursor of the histamine molecule, which plays a fundamental role in the immune system and as a neurotransmitter in the central nervous system. In addition, histidine acts as a chelating agent capable of detoxifying the body of heavy metals and contributes to the digestion process, preventing the onset of gastrointestinal problems. It also helps to preserve the myelin sheath that protects nerve cells. [10]

These are the 9 essential amino acids that exist in nature, which must be maintained at adequate and stable levels in the body. If there is a deficiency of any of them, it is possible to make up for it by eating the right foods or by supplementation. A supplement containing all these amino acids can therefore be a good option for athletes, people with protein deficiency or underweight, consumptive processes and people with sarcopenia. This formulation is known as the Master Amino Acid Pattern or MAP.

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    Sleep-wake Cycle and Immune Function: Streptopelia Risoria as a Model. International Journal of Tryptophan Research. 2009, 2, 23–36.
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  • [8] Martínez, Y., Li, X., Liu, G. et al. The role of methionine on metabolism, oxidative stress, and diseases. Amino Acids. 2017, 49, 2091–2098.
  • [9] Kidd M, T., Nutritional considerations concerning threonine in broilers. World’s Poultry Science Journal , 2000, 56 (2), 139 – 151.
  • [10] Kessler A, T., Raja A. Biochemistry, Histidine. StatPearls. 2022.

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