L-methionine is an essential sulfur amino acid, which must be obtained from food or supplement sources.
L-methionine contributes to the synthesis of S-adenosyl-L-methionine (SAMe), which may elevate mood and support joint health, and L-cysteine, which is a component of glutathione, an important antioxidant molecule in the body. Methionine is also a transporter of the antioxidant mineral, selenium.