Amino acids

What are Amino acids?

Amino acids are organic molecules formed by a carboxyl group, an amino group, and a side-chain attached to a central carbon. The functional differences between amino acids lie in the structure of their side chains.

Amino acids are categorised as follows:

  • Essential amino acids - These cannot be synthesised by the human body and can therefore only be obtained through diet or supplementation. There are nine in total: Phenylalanine, Tryptophan, Valine, Threonine, Lysine,Leucine, Isoleucine, Methionine, and Histidine.
  • Conditionally essential amino acids - These are produced in the human body from other amino acids. However, in times of illness or physiologically stressful conditions, their synthesis may be insufficient, and they must be obtained through diet or supplementation. Glutamine, Proline, Arginine, Glycine, Tyrosine and Cysteine are considered conditionally essential amino acids.
  • Non-essential amino acids - This category entails the amino acids that are synthesised by the human body, such as Alanine, Asparagine, Aspartic Acid or Aspartate, Glutamic Acid or Glutamate, and Serine.

Positive actions of amino acids reported by scientific studies:

  • Supplying the required base molecules for the biosynthesis of proteins
  • Stimulating muscle protein synthesis in adults when including leucine


Moro T et al. Amino Acid Sensing in Skeletal Muscle, Trends Endocrinol Metab. 2016 Nov;27(11):796-806. doi: 10.1016/j.tem.2016.06.010.

Belitz H.D. et al. (2009). Food Chemistry "1 Amino Acids, Peptides, Proteins", 4th revised and extended Edition, 8-9.

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