Nature's second line of defense is a removal and repair system for damaged macromolecules, but this too is imperfect. Consequently, oxidative damage accumulates through life and increases in old age. Oxidative stress increases when antioxidant defenses weaken or free radical levels rise. It is now widely accepted that oxidative stress figures prominently in cell transformation and cancer, atherosclerosis and heart disease, both acute and chronic inflammatory conditions, cataracts, and neurodegenerative diseases such as Alzheimer's disease. We can decrease oxidative stress by bolstering the body's antioxidant defenses and reducing free radical generation or exposure.
Oxidative stress tends to escalate over time.
When a cell or molecule is damaged by oxidative stress, it tends to malfunction so as to cause additional oxidative stress. Oxidative stress and bioenergetic deficiency are locked together in just such a vicious cycle. The downward spiral of increasing oxidative damage and dwindling cellular energy production is a hallmark of aging and many degenerative diseases. The theory holds that as we age and the oxidative damage the body has sustained over the years takes its toll, the level of oxidative stress itself rises. This may be compared to a rusting, crumbling building that is subjected to ever harsher rain and wind.