What Are Amino Acids?

Amino acids are a class of naturally occurring molecules with great nutritional importance for the human being. In common sense, the word amino acid is associated with sports supplements, such as essential amino acids (EAA) or branched amino acids (BCAA), but in reality, they are molecules that make up all living things, as well as tissue proteins, hormones, enzymes, neurotransmitters and much more.

For this reason, the automatic association between the word “amino acids” and some sports supplements is improper, as a myriad of other molecules completely unrelated to this category of products can be indicated.

In humans, proteins are made up of 20 amino acids divided into essential (8-9) and non-essential (11-12):

  • essential amino acids (EAA): leucine, isoleucine, valine, lysine, methionine, threonine, phenylalanine, tryptophan, and histidine.
  • nonessential amino acids (NEAA): arginine, alanine, aspartic acid, glutamic acid, cystine, cysteine, glycine, proline, serine, tyrosine, asparagine, and glutamine.

As mentioned above, their function is not only structural, they can interact as chemical messengers or as transporters, or they can play a minor role to provide energy to our body.

Amino acid supplements: in sport and therapy

Remaining on the topic of sports supplements/supplements, it is equally improper to associate the word amino acids with only two very common products, namely essential amino acids (EAA) and branched-chain amino acids (BCAA). This is because many other amino acids among the 20 present in food are marketed in the supplement market, equally integrated in sport but also in the medical and therapeutic context.

In fact, many amino acid supplements are used in the clinical field, including the same ones that are used in sports for performance or muscle mass. Creatine (1), essential amino acids (2), branched (2), as well as arginine (2), citrulline (2), glutamine (3) or taurine (4), are just a few examples amino acids which are notoriously used for extra-sporting and therapeutic purposes.

Paradoxically, most of the most well-known amino acid supplements in the sporting context are perhaps more useful in the medical field since many of these (BCAA, EAA, arginine, glutamine) have been remarkably re-discussed for their sporting effectiveness in recent research (5, 6). In simple words, they are not used so much in healthy subjects, let alone sporting ones, but rather they can be useful in the elderly, in diabetics, in cardiopathy, in burns, in neurodegenerative diseases and much more.

In many cases, it is known that some amino acids are therefore shown to be useful in people with deficiencies or with needs above the norm, but not in those who already follow a complete diet with an adequate intake of proteins (that is amino acids).


  • Gualano B et al. In disease and health: the widespread application of creatine supplementation. Amino acids. August 2012; 43 (2): 519-29.
  • Jonker R et al. Role of specific dietary amino acids in clinical conditions. Br J Nutr. August 2012; 108 Suppl 2: S139-48.
  • McRae MP. Therapeutic benefits of glutamine: a general review of meta-analyses. Biomed Rep. 2017 May; 6 (5): 576-584.
  • Schaffer S, Kim HW. Effects and mechanisms of taurine as a therapeutic agent. Biomol Ther (Seoul). May 1, 2018; 26 (3): 225-241.
  • Kerksick CM et al. ISSN Exercise and Sports Review Update: Research and Recommendations. J Int Soc Sports Nutr. August 1, 2018; 15 (1): 38.
  • Helms ER et al. Evidence-based recommendations for preparing the natural bodybuilding contest: nutrition and supplementation. J Int Soc Sports Nutr. May 12, 2014; 11: 20.