Pure Encapsulations NAC 900mg -NAC, short for N-Acetyl-L-Cysteine, is a dietary supplement derived from the amino acid l-cysteine. It effectively combats free radicals and reduces oxidative stress caused by heavy metals, while promoting healthy levels of the antioxidant glutathione. Animal studies have shown potential for NAC to protect against the build-up of mercury and cadmium in the kidneys and liver by maintaining proper glutathione levels and protecting tissues from damage. Additionally, NAC has been found to have a positive impact on lung tissue through its powerful antioxidant properties.