What is N-Acetyl- Cysteine (NAC)? N-Acetyl Cysteine is most commonly taken to support overall wellness.* N-A-C comes in a variety of supplement products for customer preference, including liquid drops, bulk powders, chewable tablets and cream. For additional benefits NAC is sometimes taken with antioxidants like selenium or a blend of complimentary vitamins like vitamin c, for optimal Men & Women's Health. Free-radicals are everywhere, it's important to create a strong natural defense for your body with a quality source of NAC.