Methionine is an essential amino acid, meaning that the body cannot produce it on its own and must obtain it from food. It plays a crucial role in various biological processes, including protein synthesis and the production of important molecules like cysteine and glutathione. Foods rich in methionine include meat, fish, dairy products, and some nuts and seeds. In addition to its role in protein formation, methionine is involved in the metabolism of fats and helps maintain healthy liver function. It also contributes to the production of SAMe (S-adenosylmethionine), a compound that supports mood regulation and joint health.