| ≥1 piece |
Cysteine is a nonessential amino acid, which means that it is manufactured from other amino acids in the liver; it does not have to be obtained directly through the diet. It is synthesized in the liver from methionine. Cysteine is an important free radical antioxidant in cellular systems. It blocks oxidants of the free radical type that may be engaged in certain forms of cellular pathology, including aging, carcinogenesis, diabetes mellitus, and the development of heart disease. Cysteine is incorporated in the cellular glutathione, which works along with vitamin E to protect cells against free radical oxidant damage. Deficiencies of a nonessential amino acid will not occur if a well-balanced diet is consumed because the intake of proper foods will allow the body to produce exactly the amount of amino acid required to function optimally. For cysteine, deficiencies of methionine, vitamin B-2, or selenium will result in poor metabolism of cysteine and reduced antioxidant protection.