Pure Encapsulations NAC 900mg 120 capsulesN Acetyl L Cysteine (NAC) is a derivative of the dietary amino acid L cysteine. 1 NAC has a high affinity for lung tissue, which it supports through mucolytic and antioxidant action. NAC promotes healthy lung tissue and respiratory function. Supports cellular antioxidant defense system as a radical scavenger that supports glutathione levels in tissues. Helps support tissue detoxification.