Pure Encapsulations NAC 600mg 90 Veggie CapsNAC 600mg Powerful free radical defense N Acetyl L Cysteine (NAC) is a derivative of the nutrient derived amino acid l cysteine. NAC scavenges free radicals and decreases oxidative stress produced by heavy metals to promote antioxidant defence. It is also a precursor to the antioxidant glutathione, and supplemental NAC increases tissue levels of glutathione. Several animal studies suggest that NAC administration may also assist in moderating the