NOW Foods NAC - Free Radical Protection* N-acetyl cysteine (NAC) is a stable form of the non-essential amino acid cysteine. It is a sulfur-containing amino acid that acts as a stabilizer for the formation of protein structures, and promotes the formation of glutathione.* Glutathione is a powerful free radical scavenging compound that also helps to maintain normal, balanced immune system function.* In addition, NAC can help to support healthy brain and neuronal tissues.*Superior Manufacturing ? GMP Quality Assured ? UL Dietary Supplement Certification Also available in 1,000mg 120 tabs and 600mg 100 capsules and 600 mg 250 cap sizes. Add to your cart because your health is worth it.