N-Acetyl-L-methionine is a form of the amino acid methionine. It is an intermediate in the conversion of L-methionine to S-adenosylmethionine, which is involved in methylation reactions in cells. N-Acetyl-L-methionine has been shown to be effective against nitrite ion, a reactive nitrogen species that causes oxidative stress and damage to DNA, RNA, and proteins. It also has been shown to have biological properties for the prevention of ischemia reperfusion injury following cardiac arrest and liver transplantation. N-acetyl-L-methionine may also have benefits for individuals with high body mass index or rats with liver microsomes.