
Glutathione is the main antioxidant found inside human cells, where it plays a vital role in protecting against oxidative stress. This is significant because cellular activities—such as energy production, enzyme function, and tissue synthesis—generate most of the body's oxidation, requiring a strong antioxidant defense. While glutathione supplements are available, they are often ineffective because the molecule is too large to naturally enter cells. Specialized delivery systems can be expensive and still result in poor absorption. Instead, the body can synthesize its own glutathione using the amino acid cysteine, which is provided by supplements like N-acetyl cysteine (NAC). This internal production is more efficient, ensuring that cells have the antioxidant protection they need. Thus, supporting the body's natural ability to make glutathione is preferable to relying on direct supplementation.