Methionine is the least abundant of all amino acids. Despite this verity, methionine is essential, and is an important chelating agent that assists in both metabolic and growth processes. Along with cysteine and cystine, methionine is also a sulfur-containing amino acid. Cysteine and methionine are the only sulfur-containing amino acids readily coded for by DNA.

Methionine (along with choline and inositol) is included in a group of compounds referred to as lipotropics. Lipotropic literally means “fat loving”, and these specialized compounds aid the liver in processing fats by increasing the production of lecithin. Choline and methionine work in union to detoxify the body of amines resulting from protein synthesis, and protecting the liver from damage that is the result of fat accumulation. Methionine serves as a catalyst for choline and inositol functioning. It actively participates in the formation of D-glucose, the primary energy source of living organisms, as well.

In addition to the aforementioned roles, methionine in included in a number of biochemical reactions. Methionine is an integral element in the production of L-cysteine, glutathione, taurine, sulfate, and perhaps most notably, S-adenosylmethionine (SAMe). The varying forms of methionine include:

• L-methionine
• Ademethionine
• S-Adensyl-L-methionine