N-acetyl-L-cysteine (or NAC) and L-cysteine are powerful amino acid antioxidants. Cysteine is an important source of sulfur in human metabolism. N-acetyl-L-cysteine assists in the production of glutathione in the body. Glutathione is one of the most important antioxidants. N-acetyl-L-cysteine is the acetylated form of L-cysteine, which renders it more absorbable. It is used as an antidote for acetaminophen and other chemical poisoning. N-acetyl-L-cysteine is also used in cough syrups due to its mucolytic properties. It naturally lowers the viscosity of the mucus, making it easier to break up.
Cysteine deficiency can lead to decreased production of peptide glutathione, leading further to edema, liver damage, muscle loss, lethargy, skin lesions, and weakness.
L-cysteine can be found in cheese, yogurt, pork, turkey, duck, eggs, wheat germ, and vegetables.