Oxidative stress

Scientific

Reactive oxygen species (ROS) — superoxide anion, hydrogen peroxide, hydroxyl radical, singlet oxygen — and reactive nitrogen species (peroxynitrite, nitric oxide-derived species) are produced continuously by:

• Mitochondrial respiration. Approximately 1–2% of oxygen consumed by mitochondria during ATP production “leaks” as superoxide, the principal endogenous ROS source
• NADPH oxidase activity in immune cells (deliberate ROS production for pathogen killing)
• Xanthine oxidase, cytochrome P450 systems, and several other enzymes producing ROS as part of normal metabolism
• Environmental exposures — UV radiation, air pollution, heavy metals, pesticides, cigarette smoke

The body’s antioxidant defenses include:

• Endogenous enzymes. Superoxide dismutase (SOD), catalase, glutathione peroxidase, peroxiredoxins — produced by the body and forming the primary antioxidant defense
• Endogenous small molecules. Glutathione (the master cellular antioxidant), uric acid, bilirubin, alpha-lipoic acid
• Dietary antioxidants. Vitamin C, vitamin E, carotenoids, polyphenols, selenium (a glutathione-peroxidase cofactor)

Mild oxidative stress serves important signaling functions: muscular adaptation to exercise, mitochondrial biogenesis, cellular hormesis (the beneficial-stress response to mild challenges), immune-cell pathogen-killing. Hormetic interventions (exercise, [[cold-exposure|cold exposure]], fasting, sauna, plant polyphenol intake) trigger transient mild oxidative stress that drives beneficial adaptation.

Sustained pathological oxidative stress damages cellular components: lipid peroxidation degrades cell membranes; protein oxidation impairs enzyme function; oxidative DNA damage initiates mutations and signals cell-cycle arrest or apoptosis. Chronic oxidative stress, alongside chronic inflammation, is foundational to aging and most chronic disease — cardiovascular, neurodegenerative, autoimmune, cancer.

Practical

Lifestyle inputs that modulate oxidative-stress balance:

• Polyphenol-rich diet — berries, dark chocolate, green tea, herbs, spices, extra-virgin olive oil. The most direct dietary support for antioxidant defenses.
• Cruciferous vegetables — [[broccoli|broccoli]], kale, [[cabbage|cabbage]], watercress, arugula contain glucosinolates that activate the Nrf2 transcription factor, the master regulator of endogenous antioxidant gene expression.
• Adequate sleep supports glutathione production and overnight antioxidant maintenance.
• Hormetic interventions — exercise, [[cold-exposure|cold exposure]], fasting, sauna — produce mild oxidative stress that drives long-term antioxidant capacity adaptation.
• Avoiding pro-oxidant exposures — cigarette smoke, air pollution, [[ultra-processed-foods|ultra-processed foods]] high in advanced glycation end products and oxidized seed oils.

Direct antioxidant supplementation (high-dose vitamin C, vitamin E, beta-carotene) has produced inconsistent and sometimes counterproductive results in clinical trials — the master regulators of the body’s redox balance respond better to intervention through endogenous-defense activation than through direct exogenous antioxidant flooding.

See also

Auto-generated from this entry’s typed relations: frontmatter, grouped by relation type so the editorial signal isn’t flattened.

• Shares substrate with: [[inflammation]] · [[polyphenols]]