Monosodium glutamate (MSG) is a flavor enhancer that is commonly added to restaurant foods, canned vegetables, soups, deli meats, and other processed foods. MSG is the sodium salt of glutamic acid, which is naturally present in many foods. It is produced by fermenting plant-based ingredients such as sugar cane, sugar beets, cassava, or corn. MSG is a white, odorless, crystalline powder that dissolves easily in water, separating into sodium and free glutamate.
While some people may be more sensitive to MSG than others, experts generally consider it safe, especially in smaller doses. A 1995 report from the Federation of American Societies for Experimental Biology (FASEB) for the United States Food and Drug Administration (FDA) concluded that MSG is safe when "eaten at customary levels". However, a subgroup of otherwise-healthy individuals may develop an MSG symptom complex when exposed to 3 g of MSG in the absence of food. Symptoms that some have claimed occur after consuming MSG include nausea, weakness or fatigue, heart palpitations, headache, sweating or flushing, numbness, chest pain, hives, and swelling of the throat.
MSG is found naturally in some foods, including tomatoes and cheese in this glutamic acid form. It is also present in a variety of other additives, including hydrolyzed vegetable protein, autolyzed yeast, hydrolyzed yeast, yeast extract, soy extracts, and protein isolate, which must be specifically labeled. Since 1998, MSG cannot be included in the term "spices and flavorings".
