What is monosodium glutamate (MSG)?

MSG is a flavor enhancer which has been used effectively for nearly a century to bring out the best flavor of foods. Its principal component is an amino acid called glutamic acid or glutamate.

Glutamate is found naturally in protein-containing foods such as meat, vegetables, poultry and milk. The human body also produces glutamate naturally in large amounts. The muscles, brain and other body organs contain about four pounds of glutamate, and human milk is rich in glutamate, compared to cow's milk, for example.

Glutamate is found in two forms: "bound" glutamate (linked to other amino acids forming a protein molecule) and "free" glutamate (not linked to protein). Only free glutamate is effective in enhancing the flavor of food. Foods often used for their flavoring qualities, such as tomatoes and mushrooms, have high levels of naturally occurring free glutamate.