L-Methionine is classified as an essential amino acid, which means that it cannot be manufactured by the body. It must be obtained through the diet or by supplementation. L-Methionine supports the production of the cellular antioxidant, glutathione, and thereby assists in natural detoxification processes. In the body, L-Methionine can also be converted into SAMe (S-Adenosyl Methionine), a compound that supports healthy joints. L- Methionine is the building blocks that our bodies use to make proteins. Methionine is found in meat, fish, and dairy products, and it plays an important role in many cell functions. Methionine is used to prevent liver damage in acetaminophen (Tylenol) poisoning.