Methionine functions as a building block for proteins and as a source of polyamines, and is the precursor of SAM (S-adenosylmethionine), the universal methyl donor for over 100 reactions. Many of these reactions (often the synthesis of compounds) are vital to the survival of the cell and the organism. It is necessary for normal metabolism and growth.
Methionine has myriad functions. Composed partly of sulfur, this acid promotes hair growth and helps protect against skin and nail disorders. It is a lipotropic along with choline, inositol, and betaine. As a lipotropic, it prevents too much fat buildup in the liver by increasing production of lecithin. It also is used in the prevention and treatment of certain types of liver damage. It is beneficial to the digestive system and is involved in detoxification functions and the chelating of heavy metals out of the body. Methionine alleviates bladder irritation by regulating the production of ammonia and has been used as a treatment for rheumatoid hay fever and toxemia induced by pregnancy. Methionine is included in nutritional supplements used as anti-fatigue agents.