Nac Powder by Trace Minerals (N-acetyl L-Cysteine) is a supplement form of cysteine. Cysteine is a semi-essential amino acid. Cysteine is found in most high-protein foods, such as chicken, turkey, yogurt, cheese, eggs, sunflower seeds and legumes. Nac is an immediate precursor to a very precious substance that our body makes called glutathione. Mix 1 scoop (2.5 g) with 4-8 oz of water daily. For adults only. Keep out of reach of children. We are America s #1 Trace Minerals Supplement Brand. Since 1972, Trace Minerals' branded products have been recognized around the world as the pioneer of ionic trace mineral products that have supported consumers in living healthy lives. Our products are third-party tested to give you the highest quality product with maximum absorption. Feel the difference with Trace Minerals!