Glutamate is produced in the human body and plays an essential role in metabolism. Almost two kilograms (about four pounds) of naturally occurring glutamate are found in muscles, in the brain, in kidneys, in the liver and in other organs and tissues.
The monosodium glutamate added to foods to improve taste represents only a small amount of the total glutamate present in most foods. For example, the average daily amount of glutamate consumed in bound form as protein from food is about 15 grams. In addition, about 1 gram of free glutamate in food would also be consumed during the same day. In contrast, average daily intake of added monosodium glutamate ranges between 0.5 grams and 3.0 grams a day, dependent upon local dietary customs and cuisine.
In addition, glutamate is found in abundance in mothers' milk, at levels about four to six times that found in cows' milk:
| Free Glutamate in Mother's Milk | Mg/100 Grams |
| Humans | 21.6 |
| Chimpanzees | 38.9 |
| Rhesus monkeys | 4.6 |
| Cows | 1.9 |
| Sheep | 1.4 |
| Mice | 2.2 |
