TO PUT IT IN ONE WORD – Denham Harman free radical theory of aging (developed in the 1950s) is IN-CONCLUSIVE! at best.
According to free radical theory of aging, organisms age because their cells accumulate free radical damage over time. A free radical is a reactive atom or molecule that has a single unpaired electron in an outer shell. It can cause, so called, oxidative stress or a disbalance between oxidative and reducing species in our cells. This leads to damage of cellular components. DNA, proteins, cholesterol or fatty acids are under fire. Antioxidants are opposite – reducing agents. They limit oxidative damage to biological structures by protecting them from free radicals.
Antioxydants and Aging
There is no proof that antioxidants such as vitamin A, vitamin E, vitamin C, beta-carotene if taken orally, will slow the process of aging.
Many processes operate together in complex biological environment. Changing only one parameter, such as antioxidant level, is not enough. It is usually quickly counterbalanced by some opposite acting process.
Calorie Restriction helps
Calorie restriction on the other hand, has positive effects on the lifespan of people. Even though it is, similar to physical activity, accompanied by increase in oxidative stress. This is probably due to oxidative stress resistance. It increases in calorie restriction and very likely in physical activity as well.