White crystalline substance, a sodium salt of the amino acid glutamic acid .
MSG is used to intensify the natural flavour of meats and vegetables. It elicits a unique taste, called in Japan umami , different from the four basic tastes. Originally derived from seaweed and first used in Japan in 1908, it has become a common ingredient in Chinese and Japanese cooking. MSG in large amounts may have physical effects, including an allergic reaction commonly called "Chinese restaurant syndrome."