Description Solarays NAC is the acetylated form of the amino acid L-cysteine. It is a precursor to glutathione, which is part of the bodys natural antioxidant defense system. Properties and benefits of NAC NAC can raise cellular glutathione more effectively than L-cysteine or preformed glutathione and is widely recommended by practitioners. Vitamin C supplements are often recommended when taking NAC. How to take NAC? It is recommended to take it preferably outside of meals. Composition of NAC Per 1 capsule: NAC (295 mg).