We age and die as a result of our body accumulating oxidative damage. This damage reduces the function of these cells and when enough cells have been damaged or die, tissue fails to function and we die from organ failure.
The best way to live your healthiest life is to reduce future oxidative damage as much as possible. The key to doing this is to restore and maintain high glutathione levels. Glutathione is the main antioxidant in your body that quenches the radicals that damage cells.
Healthy glutathione levels have been associated with longevity. Studies have shown that centenarians have similar glutathione levels to that of young people. In contrast, people who die at a younger age almost always have a low level of glutathione, which almost certainly contributes to the degenerate condition.
Can glutathione levels be restored? Yes. Studies on middle age people showed that taking supplements restored their glutathione levels to that of their younger counterparts in 24 weeks. Studies on mice taking similar supplements found those who received supplements lived 24% longer than those who didn't.
Does this mean humans taking supplements that restore glutathione levels will live longer lives? These studies are underway, with promising results so far. Biochemical markers of longevity improved with supplementation, though it remains to be seen whether these improvements actually result in longer lifespans.
What's the best way to restore glutathione levels? Glutathione is made up of cysteine, glycine and glutamic acid. Cysteine and glycine levels were low in these middle aged people whereas glutamic acid levels were normal, indicating that the body's glutathione levels are low due to low levels of cysteine and glycine in the diet. Reserachers found that supplementing with glycine and NAC (7 g of each per day) were effective. NAC is a compound that is rapidly converted into cysteine.
Can Vitamin U be substituted for NAC? Quite possibly, although this has not been tested directly. Vitamin U is an amino acid (S-methylmethionine) is found in all produce, especially stalky and cruciferous vegetables. Vitamin U is integrated into the human body by the enzyme BHMT2, primarily in the liver and kidney but also to a small extent in many other tissues. One advantage of taking Vitamin U over NAC is that these enzymes in the liver and kidney specifically regulate the integration of Vitamin U, converting it into cysteine-->glutathione when needed without any of the side effects of high level NAC dosing.
While restoring glutathione levels will minimize further damage from oxidative stress, it won't directly reverse existing damage. However, restoring healthy glutathione levels will allow your body's natural repair systems to heal your body the best they can.
Edited - 27Nov2025