Oxidative stress occurs when the production of reactive oxygen species outpaces the body’s antioxidant defenses, leading to damage of DNA, proteins and lipids. These reactive molecules, such as superoxide and hydrogen peroxide, are natural byproducts of cellular metabolism, particularly in mitochondria, and also arise from external sources like pollution, tobacco smoke and radiation.

Cells possess enzymatic defenses including superoxide dismutase, catalase and glutathione peroxidase, as well as non enzymatic antioxidants like vitamins C and E, glutathione and plant polyphenols. When these systems are overwhelmed or impaired, oxidative stress contributes to inflammation, cellular dysfunction and tissue injury.

Research links chronic oxidative stress to aging and a wide range of diseases. In cardiovascular disease it promotes endothelial dysfunction, low density lipoprotein oxidation and atherosclerotic plaque formation. In neurodegenerative conditions such as Alzheimer’s and Parkinson’s disease it damages neurons and impairs mitochondrial function. Oxidative stress is also implicated in diabetes related complications, cancer initiation and progression, chronic obstructive pulmonary disease and kidney disorders.

Mitochondria play a central dual role as both a major source and a sensitive target of reactive oxygen species. Persistent oxidative damage to mitochondrial DNA and membranes can trigger cell death pathways and amplify dysfunction, creating a vicious cycle.

Lifestyle and environmental factors strongly influence oxidative balance. Diets rich in fruits, vegetables and other sources of antioxidants, regular physical activity, good sleep, stress reduction and avoidance of smoking and excessive pollution exposure can support endogenous defenses. Experimental and clinical studies continue to investigate targeted antioxidants, mitochondrial protectants and strategies that modulate redox signaling rather than simply suppressing all reactive oxygen species.