NAC has cytoprotective (cell-protecting) effects, which work through antioxidant and anti-inflammatory mechanisms. On the antioxidant side, although the NAC molecule itself has the ability to scavenge reactive oxygen species (ROS), the antioxidant effects of NAC in the body mainly occur through increasing glutathione levels and other indirect mechanisms.[1] NAC increases glutathione levels by acting as a source of the amino acid cysteine, which is a rate-limiting building block for glutathione production.[2] The anti-inflammatory effects of NAC are indirect and work through its antioxidant activity, which in turn inhibits the pro-inflammatory transcription factor NFKB-Activity[3] and reduces pro-inflammatory cytokines like IL-8, IL-6, and TNF-α.[4]
As a mucolytic agent, NAC decreases the thickness of mucus (sputum) by reducing oxidized sulfur bonds between mucus proteins, breaking them up. In the respiratory tract, this effect allows for better mucociliary clearance (the self-cleaning mechanism within the airways) so mucus can be more effectively expelled from the lungs.[5]
N-acetylcysteine also appears to modulate glutamate and dopamine neurotransmission in a way that may be beneficial for certain neuropsychiatric disorders such as schizophrenia and substance use disorder. However, further research is needed to support these effects.[6]