Body cells and tissues are threatened continuously by damage caused by toxic free radicals and reactive oxygen species (e.g., peroxides) which are produced during normal oxygen metabolism, by other chemical reactions, and by toxic agents in the environment. Free radicals, once formed, are capable of disrupting metabolic activity and cell structure. When this occurs, additional free radicals are produced which, in turn, can result in more extensive damage to cells and tissues. The uncontrolled production of free radicals is thought to be a major contributing factor to many degenerative diseases. NAC is a precursor for the sulfur amino acid cysteine, and cysteine is used by the body to synthesize glutathione. Glutathione is a naturally occurring tripeptide which is a major component of two anti-free radical enzymes: glutathione peroxidase and glutathione reductase. As such, glutathione offers one mechanism for scavenging toxic free radicals and inhibiting peroxidation thereby slowing down free-radical catalyzed chain reactions. Glutathione per se is well absorbed in the intestine, and enters the blood and other extracellular compartments where it exerts much of its beneficial antioxidant effects.
However, it can not effectively enter the cell. In contrast to glutathione, NAC is efficiently transported into the cell where it is readily converted to cysteine for glutathione synthesis. Thus, supplementation with NAC can raise intracellular glutathione levels. Providing supplemental cysteine to elevate intracellular glutathione levels is generally not advised due to cysteineÕs inherent toxicity. NAC is virtually non-toxic and well absorbed, which is why supplementation with NAC is recognized as a safe, highly effective method of increasing intracellular glutathione stores. Aside from providing cysteine as a glutathione precursor, NAC also appears to have antioxidant properties as such, and is a valuable sulfur donor for various metabolic needs. Current research also suggests that oral NAC may prevent acute exacerbations of chronic bronchitis and decrease associated morbidity.