N-ACETYL-L-CYSTEINE (NAC) is an amino acid and antioxidant. It is a precursor in the body to the critical antioxidant glutathione which is produced intracellularly particularly in the liver. NAC is significantly more cost effective than taking glutathione. . . NAC has a biological half-life of 1 1/2 hours in the bloodstream. Jarrow Formula's NAC Sustain will release in the small intestine over a 2-4 hour period in order to help maintain blood levels over a longer period of time.Other products from HerbsPro