A study found that giving mice high doses of vitamin E markedly increased the median lifespan by 40 percent, and increased maximum lifespan by 14 percent. Supplementation raised brain vitamin E to twice the normal levels.

The researchers found that mitochondrial free radical and lipid peroxidation levels rose progressively with the aging of animals, as occurs in humans. The animals also developed progressive damage to their proteins (protein carbonyls).

The damage could be prevented with vitamin E supplementation. Animals that were given vitamin E demonstrated marked improvement in neurological performance, while decline in age-associated neurological function was prevented.

Additional studies have shown that other supplements — such as acetyl-L-carnitine, R-lipoic acid, and flavonoids from vegetable extracts — can do the same thing.

What these antioxidant supplements have in common is that they protect mitochondria, prevent free radical and lipid peroxidation accumulation, and promote repair.

Studies have shown that as mitochondria age, the electron transfer used to generate cell energy (ATP) is impaired. Supplementing with vitamin E or performing moderate exercise can prevent this decline in energy production.

The dose used in these studies was equal to 1,296 mg or close to 1,400 IU of vitamin E for humans. Taking 400 IU of vitamin E three times a day will get you close enough.