Amino acids function as the building blocks of proteins. Chemically, amino acids are organic compounds containing an amino (NH2) group and a carboxyl (COOH) group.
There are about 20 amino acids required by the human body, but 8 of these cannot be synthesized by our bodies. These are known as the 'essential amino acids.' Protein foods that contain all 8 of these in sufficient quantities are called 'complete proteins'. Some of these 'complete proteins' are egg yolks, fresh milk, liver and kidney.
Amino acids are classified as essential, nonessential and conditionally essential. If body synthesis is inadequate to meet metabolic need, an amino acid is classified as essential and must be supplied as part of the diet.
Essential amino acids include leucine, isoleucine, valine, tryptophan, phenylalanine, methionine, threonine, lysine, histidine and possibly arginine.
Nonessential amino acids can be synthesized by the body in adequate amounts, and include alanine, aspartic acid, asparagine, glutamic acid, glutamine, glycine, proline and serine.
Conditionally essential amino acids become essential under certain clinical conditions
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