Glutamic acid

Glutamic acid is a non-essential amino acid that occurs naturally and abundantly in protein-rich foods — tomatoes, aged cheeses, cured meats, mushrooms, and fermented sauces all owe much of their savoury, mouth-filling character to free glutamate. In its role as a food additive, glutamic acid functions as an umami flavour enhancer, intensifying savoury tastes without contributing a flavour of its own. It is the parent compound of the entire glutamate additive family (E620–E625), of which monosodium glutamate (E621) is the most widely used.

JECFA assessed glutamic acid in 1987 and classified the ADI as "not specified," meaning that the available data, including extensive evidence from its role as a dietary amino acid and metabolic intermediate, did not indicate a need to set a numerical upper intake limit. Glutamate is a normal neurotransmitter and is involved in energy metabolism throughout the body; it is generated and consumed continuously during protein digestion and cellular metabolism.

Glutamic acid is approved throughout the EU and in most global food markets for use as an acidity regulator and flavour enhancer in soups, condiments, snacks, and processed meat products. It is often used in combination with nucleotide enhancers (E626–E635) because glutamate and nucleotides interact synergistically, meaning their combined effect on umami intensity is greater than the sum of either alone. Some individuals report sensitivity to added glutamates — symptoms sometimes referred to as "MSG sensitivity" — though large controlled studies have not consistently confirmed a causal relationship. Consumers who wish to limit glutamate intake should check for E620–E625 and E621 on ingredient labels.