Oxidative stress is an imbalance between the formation of reactive oxygen species (free radicals) and the body's ability to neutralize them with antioxidants and repair the damage. When there are too many radicals, they damage proteins, membrane lipids and DNA.
A small amount of reactive oxygen species is normal and even necessary: they take part in signaling and in the killing of microbes by immune cells. Problems begin when the defenses cannot cope and damage accumulates, accelerating cellular senescence.
Where free radicals come from
The main internal source is the mitochondria: during energy production, part of the oxygen turns into reactive forms. Radicals are also added by external factors — smoking, ultraviolet light, air pollution, excess alcohol, chronic inflammation.
The body defends itself with its own antioxidant enzymes (superoxide dismutase, catalase, glutathione peroxidase) and with substances from food — vitamin C, vitamin E, polyphenols. Oxidative stress is closely intertwined with inflammation: they reinforce each other and together raise inflammatory markers.
The link with aging and disease
According to the free-radical theory of aging, the accumulation of oxidative damage is one of the mechanisms of age-related changes; it damages DNA, shortens telomeres and contributes to atherosclerosis, diabetes, neurodegeneration (Alzheimer's and Parkinson's diseases) and cancers. Chronic psychological stress increases oxidative stress as well, raising the overall allostatic load.
An important nuance: mass intake of antioxidant supplements (high doses of vitamins A, E, beta-carotene) does not prolong life, and in several meta-analyses even increased mortality. A diet rich in vegetables and fruit is more useful. A moderate, brief oxidative stimulus, on the contrary, trains the cell's defenses — this is the phenomenon of hormesis (mitohormesis).
Calculate using this marker
Calculators where Oxidative stress is used directly:
Frequently asked questions
Do antioxidant supplements help slow aging?
There is no convincing evidence. In studies, high doses of vitamins A, E and beta-carotene did not prolong life and sometimes increased mortality. It is better to get antioxidants from vegetables, fruits and berries than from pills.
How can oxidative stress be reduced?
The basics work: quitting smoking, moderate physical activity, adequate sleep, a diet with vegetables and fruit, and control of chronic inflammation. It is lifestyle, not supplements, that gives a lasting effect.
Related terms
Sources
- Wikipedia — Oxidative stress
- Oxidative Stress: Harms and Benefits for Human Health (Oxid Med Cell Longev, 2017)