Glutamic acid is just one of many amino acids that are the building blocks of proteins.
It occurs naturally in many foods such as tomatoes, milk, and mushrooms. It is also found in the cells of our bodies, including mother's milk, and involves a wide variety of brain functions since it functions as a neurotransmitter. This natural glutamate in plants and animals is known as L-glutamic acid. Broken down this way, it is harmless. Its chemical formulation has been modified and it is technically known as D-glutamic acid.