NAC, the acetyl derivative of L-cysteine, is more stable than L-cysteine, and can convert into L-cysteine after being absorbed. NAC is a natural source of sulfur for metabolism, and an antioxidant that supports glutathione synthesis.* NAC may be used instead of L-cysteine as an adjunct to Item #70130 Original AntiOx. Free form amino acid, high purity, well tolerated, and in tablet form to insure potency.