Monosodium glutamate (MSG) is a flavor enhancer often added to restaurant foods, canned vegetables, soups, deli meats and other foods. The U.S. Food and Drug Administration (FDA) has classified MSG as a food ingredient that's generally recognized as safe. But its use is still debated. For this reason, when MSG is added to food, the FDA requires it to be listed on the label.

MSG has been used as a food additive for many years. During this time, the FDA has received many reports of concerning reactions that people have attributed to foods that had MSG in them. These reactions — called MSG symptom complex — include:

• Headache
• Flushing
• Sweating
• Face pressure or tightness
• Lack of feeling (numbness), tingling or burning in the face, neck and other areas
• Quick, fluttering heartbeats
• Chest pain
• Feeling sick (nausea)
• Weakness

But researchers have found no clear proof of a link between MSG and these symptoms. Researchers admit, though, that a small number of people may have short-term reactions to MSG. Symptoms are often mild and don't need to be treated. The only way to prevent a reaction is to not eat foods that have MSG in them.