Amino acids are the building blocks of protein in the body and are essential for the synthesis of structural proteins, enzymes, some hormones and neurotransmitters. Amino acids are also involved in numerous metabolic pathways that affect exercise metabolism. Consequently, it has been suggested that athletes involved in intense training require additional protein in the diet or that they should supplement their diet with specific amino acids.

There are twenty amino acids which are coded for DNA and therefore are used for protein synthesis. Of these twenty, humans can only produce ten within their body. These ten are known as non-essential amino acids since it is not essential that we get them through food or supplementation because our bodies can produce them. The ten essential amino acids that we can produce are alanine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, proline, serine and tyrosine. Tyrosine is produced from phenylalanine, so if the diet is deficient in phenylalanine, tyrosine will be required as well.

The other ten must be supplied in the food we eat or through supplementation. Failure to obtain enough of even one of the ten essential amino acids can result in a degradation of the body's proteins, (your muscle) to obtain the one amino acid that is needed. Unlike fat and starch, the human body does not store excess amino acids for later use so the amino acids must be in the food we eat every day.

The essential amino acids are arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. These amino acids are required in the diet because the human body does not have all the the enzymes required for the biosynthesis of all of the amino acids.

Below is a list of the twenty amino acids that are coded by DNA for use in protein synthesis. There are many other amino acids such as ornithine and GABA for example, that have important uses in our body but are not used in protein synthesis.  Creatine is also considered an amino acid and is actually a combination of three amino acids - Arginine, Glycine and Methionine.

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