Amino acids are building blocks of proteins. There are 20 amino acids needed for humans. Out of these 11 can be synthesized in human body but 9 amino acids can not be produced by human body and obtained from plant and animal sources. Deficiency of amino acids can cause deficiency of proteins in body. Many conditions like depressed immune system, weight loss, pressure sores, diarrhea, hair and skin depigmentation, muscle weakness and loss of lean body mass are related with amino acid deficiency.
The disease caused due to the deficiency of vital amino acids in the diet of a person is known as phenylketonuria (which is abbreviated as PKU).
Phenylketonuria is a genetic disorder. A person suffering from phenylketonuria is called a phenylketonuric. Phenylketunorics suffer from a lack phenylalanine hydroxylase, which is the enzyme essential to speed up the metabolism rate of the essential amino acid phenylalanine.
Though PKU is a rare genetic disorder, if it is left untreated it can cause progressive mental retardation and brain damage, caused by the accumulation of phenylalanine and the by-products of its breakdown. The essential amino acids are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine. These are considered essential or indispensable amino acids because they are required in the diet of a human being, and should be given as supplements in the diet as they cannot be synthesised as such by the human body. Arginine, cysteine, glycine and tyrosine are also considered to be conditionally essential amino acids as they are administered to organisms that cannot synthesise them in adequate quantities. Individuals with classic PKU are currently reccommended a lifelong restriction of phenylalanine in their diet.
