SCI-FIT's® N-Acetyl Cysteine (NAC) is a more stable form of the sulfur amino acid L-cysteine, is a powerful antioxidant, and is an excellent precursor of glutathione. Glutathione, in combination with selenium, is a precursor of glutathione peroxidase. Glutathione peroxidase is one of the most important antioxidant enzymes in the body. N-Acetyl-L-Cysteine provides powerful immune support and also packs a powerful anti-toxin potential. Its ability to neutralize cell and DNA damaging free radicals can help slow down what many scientists point to as a key factor in the aging process.