NAC (N-Acetyl-Cysteine) Free Forming Amino Acid by TwinLab NAC is a precursor of glutathione in the body and protected sulfur-containing amino acid. It is a more stable and effective antioxidant than the sulfur-containing amino acid L-Cysteine. One hard gelatin capsule supplies 600mg of pure N-Acetyl-Cysteine. Suggested dosage is one capsule daily, preferably with a meal. 60 capsules, 600 mg each