GET 8X More NAC! (without having to take a handful of pills) N Acetyl Cystine ( NAC) is a powerful antioxidant you just need the right dose. We offer a clinical dose in a great tasting powder to naturally enhance glutathione levels. GSH Immune defense is a critical all natural Respiratory Antioxidant. Stir 1 serving a day in 8-10 oz of water. Physical Formulated.