NAC Sustain is in a special Sustain bilayer Quick Release/Sustained Release format of N-Acetyl-L-Cysteine (NAC), a powerful antioxidant amino acid and a precursor to the critical antioxidant glutathione. Glutathione exerts a variety of protective effects, including detoxification and intracellular defense against oxidative stress. Substances known to reduce glutathione status are acetaminophen and alcohol. The advanced bilayer Sustain tablets combine 1/3 Quick Release and 2/3 Sustained Release formats to both immediately raise and to maintain blood levels over a longer period of time. NAC Sustain releases in the small intestine over a 8 hour period, compared to the 1.5 hour biological half-life of NAC in the bloodstream.