A non-essential amino acid, first isolated in 1865. It is the predominant amino acid in most proteins, occurring as a product of the hydrolysis of the glutamine contained in proteins, playing a vital part in brain function. The various forms of glutamic acid are known as glutamates with probably the best known being monosodium glutamate .

Recent research has proposed that excessive brain receptor cell activation, caused by too much glutamate, can destroy the cells. It has been further suggested that this could play a part in neurodegenerative diseases such as Alzheimer's, Parkinson's and Huntingdon's but the part that dietary glutamates contribute is still controversial.