NAC plays an important role in detoxification and is hepatoprotective. N-Acetyl-L-Cysteine, an acetylated form of cysteine, is readily absorbed to immediately provide an efficient precursor of cysteine for continued glutathione (GSH) synthesis. Since it easily passes through cellular membranes, NAC has been shown to be readily absorbed. It is also resistant to enzymatic breakdown.  

NAC functions in protecting cells against oxidative stress and contributes to important bodily reactions. As such it is a part of the defensive mechanism toward potential carcinogens, as well as against DNA damage.

There have been numerous studies using NAC, with COPD, particularly among patients who smoke. Utilizing NAC in smokers with chronic bronchitis showed a significant reduction in the number of positive bacterial cultures in these patients. {Riise GC, et al. Eur Respir J.1994 Jan; 7(1):94-101.} Another study utilizing NAC indicated potential benefits for chronic bronchitis, resulting in a significantly lower exacerbation rate in patients administered NAC, compared to placebo. {Rassmussen, JB & Glennow, C. Eur Respir J. 1988 Apr;1(4):351-5.}