From the Manufacturer:
"L-methionine is an essential sulfur containing free form amino acid. It contributes to the synthesis of many important compounds, including s-adenosyl-methionine (sam), which is necessary for normal brain function, 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."