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. Animal and human studies of NAC have concluded it has potent antioxidant activity. In addition to its antioxidant activity, NAC is effective in promoting normal liver detoxification and protecting the liver and the kidneys from toxic insults. As a sulfur source, NAC stimulates the synthesis and activity of glutathione, an important antioxidant in its own right. Research suggests NAC is capable of enhancing immune function. NAC also helps maintain good pulmonary health due to its mucolytic activity.
In a double-blind, placebo-controlled trial, NAC positively impacted lymphocyte cell numbers, white cells that are crucial to normal immune function.
The sulfur in NAC is able to cleave the bonds in mucoproteins, which results in mucus being broken into smaller, less viscous pieces. Hence, NAC’s ability to decrease the viscoelasticity of nasal mucus and increase the clearance of mucus by the cilia by thinning secretions helps maintain good pulmonary health.