NAC Sustain is a Quick Release/Sustained Release formulation 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.* NAC Sustain is formulated with advanced bilayer Sustain™ tablets that combine 1/3 Quick Release and 2/3 Sustained Release formats both to raise and to maintain blood levels with NAC release over time.