L-methionine

L-methionine is an essential amino acid, meaning the body cannot make it and it must be obtained from food. It is a building block for proteins and is found naturally in many protein-rich foods like meat, fish, eggs, and dairy. It can be produced industrially through chemical synthesis.

L-methionine is often added to foods as a nutritional supplement, particularly in infant formulas and medical foods, to ensure adequate intake of this essential amino acid. It may also be used as a precursor in the synthesis of other compounds and can contribute to flavor profiles in some applications.

In the U.S., L-methionine is generally recognized as safe (GRAS) by the FDA when used for nutritional purposes. International bodies like JECFA have evaluated L-methionine, and EFSA has also assessed its safety. While essential, very high intakes of methionine have been linked to certain health concerns in research, but typical dietary intakes are not associated with adverse effects. Evidence regarding specific health outcomes at typical consumption levels is generally considered reassuring.