N-acetylcysteine (NAC) is a sulfur-containing amino acid that the body naturally produces. It plays a crucial role in preventing cellular damage and may facilitate easier breathing for individuals with respiratory issues. One of its key functions is to enhance the production of glutathione, a powerful antioxidant that helps protect cells from oxidative stress. When ingested, NAC is rapidly converted into cysteine, the amino acid from which it is derived, during initial metabolism.