Fully Stocked In This Essential Nutritional Supplement (a food-based product) N-acetyl cysteine, also known as N Acetyl L Cysteine (NAC) is a supplement form of cysteine. Cysteine is known as a dispensable or non-essential amino acid. It is a sulfur amino acid and is produced from the essential amino acid methionine. It indirectly functions in the production of the body’s most abundant antioxidant – glutathione, which is made in the body’s cells. Antioxidants help neutralize free radicals that can damage cells and tissues in your body. As a mucolytic (a substance that loosening mucus in your air passageways), NAC helps treat the common cold, respiratory congestion and influenza. NAC plays an important role in your body’s detoxification process.