MSG is an effective flavour enhancer, the principal component of which is an amino acid called glutamate (also known as glutamic acid). Glutamate is a natural component, found in protein foods such as meat, poultry, vegetables and milk.
Glutamate is also produced naturally in the human body. In total, the brain, organs and muscles contain around four pounds of glutamate! Human milk is also much richer in glutamate than cow's milk.
There are two forms of glutamate. Bound glutamate, which, linked to amino acids, forms a protein and free glutamate. It is the free glutamate that has flavour enhancing qualities. Tomatoes and mushrooms often used to boost flavour within foods, have high levels of naturally occurring free glutamate.