Glutamate (from the amino acid glutamine) is found naturally in protein-containing foods such as meat, vegetables, poultry and milk. The human body also produces glutamate as part of normal metabolism. The muscles, brain and other organs store about four pounds of glutamate, and mother’s milk is rich in glutamate.
Glutamate is found in two forms: “bound” glutamate (linked to other amino acids in protein) and “free” glutamate.
Foods which are high in free glutamate, like ripe tomatoes and cheeses, are considered tasty. The umami receptors on the tongue are uniquely receptive to glutamate, which explains why free glutamate is effective in enhancing the tastiness of food.
The glutamate from MSG seasoning and the glutamate occurring naturally in food is exactly the same, and the body treats glutamate in the same way no matter what its source.
We consume between 10g and 20g of glutamate per day from our diet, of which glutamate from seasoning or condiments is less than 10%. The U.S. Food & Drug Administration (FDA) notes that a typical serving of a food with added monosodium glutamate contains less than 0.5 grams of MSG.
Glutamic acid is one of the 20 amino acids which are the building blocks of proteins in the body. Because it is made by the body as part of normal metabolism, it is a non-essential amino acid.