N-acetyl-l-cysteine, more commonly known as NAC, is a derivative of the amino acid cysteine. L-cysteine is one of the amino acids used as building blocks for protein in the body. NAC also helps to replenish levels of glutathione in the body. Glutathione is one of the body’s most important antioxidants. Each capsule contains 500mg of easy-to-absorb NAC.
Cysteine is the rate-limiting amino acid in the production of glutathione. This means that the amount of cysteine you consume in your diet, and if you don’t consume enough, can have an impact on how quickly you make glutathione. Therefore, providing it in supplement form (as NAC) may be particularly helpful for supporting the body's own production of glutathione. N-Acetyl-L-Cysteine may be defined as a precursor to glutathione, also known as the “master antioxidant”.
On its own, the amino acid l-cysteine can be quite unstable, but in the altered form of NAC, it is highly stable, and is also very well absorbed by the body. It is also one of the few amino acids that contains sulphur. Because of this NAC may have a strong sulphur-like odour, which is completely normal.