N-acetyl-L-cysteine (NAC) is a derivative of the amino acid L-cysteine. NAC has all the properties of L-cysteine, but is more water-soluble and possibly more bioavailable. NAC is absorbed into the bloodstream through the intestine, where it can cross cell membranes to be converted to L-cysteine and then into the potent antioxidant, glutathione 1.

This ingredient can be found in the following products in United States:


  1. Natural Medicines. Comprehensive Database. Therapeutic Research Faculty, 2003.