N-acetylcysteine (NAC), a sulfur-containing amino acid, is the precursor to the amino acid L-cysteine, one of the three amino acids that comprise glutathione. As well as having it's own antioxidant activity, NAC stimulates the synthesis and activity of glutathione, the master antioxidant. NAC effectively supports liver detoxification. NAC also promotes the thinning of mucus in the lungs, making it easier to clear when coughing which supports respiratory health, as well as supports clear, healthy sinuses*. Research suggests NAC also supports immune function.*