Monosodium glutamate (MSG) is the sodium salt of glutamic acid, one of the most abundant naturally occurring non-essential amino acids. Glutamic acid is found naturally in tomatoes , grapes , cheese , mushrooms and other foods. Monosodium glutamate (MSG) is a flavor enhancer or comdiment commonly added to food, canned vegetables, soups and processed meats. The Food and Drug Administration (FDA) has classified MSG as a food ingredient that's "generally recognized as safe".