N-acetyl-cysteine (NAC) is an essential amino acid for protein and glutathione formation in the body. This Now Foods supplement contains 600mg of NAC, as well as molybdenum and selenium, which are important trace elements with various functions. Selenium contributes to cell protection and the maintenance of normal hair and nails, while molybdenum is essential for the metabolism of sulfur-containing amino acids. Now Foods NAC capsules are high quality, undergo quality and purity testing in independent laboratories, and do not contain gluten or genetically engineered ingredients. Please consult a physician or alternative healthcare professional for individual consumption recommendations.