Monosodium glutamate (MSG) is the sodium salt of the naturally occurring amino acid, glutamic acid. It is denoted by the chemical formula C₅H₈NNaO₄H₂O. The compound was first isolated in 1886 and became an important industrial material in 1908 when it was discovered to enhance the flavor of certain foods. The MSG molecule can exist in two different structural forms called isomers. Only monosodium L-glutamate has a flavor enhancing effect, while the R form does not. MSG is commonly believed to be responsible for a condition known as "Chinese Restaurant Syndrome," however current evidence has failed to establish a link between the two.

The development of MSG as an important industrial material began with the isolation of glutamic acid from a wheat protein called gluten in 1886. In 1890, the chemical structure of glutamic acid was identified. The flavor enhancing ability of MSG was discovered...