Webb Nutrition® N Acetyl L-Cystine powder have been manufactured to the highest standards and comes in a handy resealable foil pouch for hygiene and freshness. Absolutely no additives, just pure NAC powder! NAC (N-Acetyl L-Cysteine) is the n-acetyl derivative of the amino acid L-cysteine, and is a precursor in the formation of the antioxidant glutathione in the body.