Amino acids are the building blocks of proteins. Each amino acid is a compound with an amine group (the nitrogen containing portion of an amino acid) at one end, a carboxylic acid group at the other end and a distinctive side chain. There are twenty amino acids, which are broken up into two categories, essential and nonessential. Essential amino acids are amino acids that cannot be synthesized by the body or that cannot be synthesized in amounts sufficient enough to meet physiological needs. Nonessential amino acids are the amino acids that the body can produce enough of without help from outside sources. The essential amino acids include: histidine, lysine, methionine, phenylalanine, isoleucine, leucine, threonine, tryptophan and valine. The nonessential amino acids include: alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, proline, serine and tyrosine.
Amino acids main function is to be the building blocks of proteins, they are used during protein synthesis, which is when cells assemble amino acids into proteins. These proteins are then used to help with growth and repair of various structures and tissues in the body like skin, hair, nails, membranes, muscles, teeth, bones, organs and tendons.
There is a different recommended intake value for each amino acid. It is advised that a doctor be consulted to ensure the correct adequate intake amount.
Deficiencies in amino acids lead to a variety of disorders including phenylkeyonuria, isovaleric academia, maple syrup urine disease and tyrosinemia. Phenylkeyonuria (PKU) is the most common amino acid disorder, this is caused by a defect in the enzyme phenylalanine hydroxylase which is used to create phenylalanine. An untreated individual with PKU may obtain an intellectual disability with severe behavioral problems.
Sources in the Diet
Meat, fish, eggs, milk, and soybeans are the best sources for amino acids.
Recent Studies and Articles
Protein and amino acid intake
Amino acids as antibiotics
Amino acids promoting optimum health
-  – Boyle, Marie A. and Anderson Sara L. Personal Nutrition. 7th ed. Belmont, CA: Wadsworth/Thomson Learning; 2007.
-  – Nelms, M. Sucher, K. Lacey, K. Roth, S. Nutrition Therapy & Pathophysiology. 2 ed. New York, NY: Cengage Learning; 2011
-  – http://www.nlm.nih.gov/medlineplus/ency/article/002222.htm