- A water-soluble compound which is needed for B vitamin action and is important for brain function and fat metabolism. It can be synthesized in the body by healthy humans when adequate methionine is present in the diet and is not strictly a vitamin. It is found in high concentration in most animal tissues and egg yolk is the richest source. deficiency may cause fatty liver and a predisposition to cirrhosis of the liver. It has no known toxicity.
- noun a compound involved in fat metabolism and the precursor for acetylcholine