Oxidative stress, aging, and diseases: A review Oxidative stress arises from an imbalance between reactive oxygen and nitrogen species (RONS) and antioxidant defenses. Aging is characterized by progressive loss of tissue and organ function, and oxidative stress is implicated in age-related conditions such as cardiovascular diseases (CVDs), chronic obstructive pulmonary disease (COPD), chronic kidney disease (CKD), neurodegenerative diseases, and cancer. Oxidative stress biomarkers can provide insights into treatment efficacy and guide drug selection. Antioxidant therapy may benefit several diseases, but further research is needed to confirm its effectiveness. Oxidative stress is caused by both endogenous and exogenous sources, including NADPH oxidase, myeloperoxidase, and environmental factors like pollution and drugs. RONS cause oxidative modifications of cellular macromolecules, leading to markers of oxidative stress. Oxidative stress contributes to cellular senescence, which is linked to aging and age-related diseases. The oxidative-inflammatory theory of aging suggests that chronic oxidative stress disrupts homeostasis, leading to inflammation and increased age-related morbidity and mortality. Oxidative stress is involved in CVDs, diabetes, COPD, CKD, cognitive impairment, and cancer. In CVDs, oxidative stress contributes to atherosclerosis and vascular dysfunction. In diabetes, oxidative stress accelerates complications. In COPD, oxidative stress leads to lung damage and impaired immune function. In CKD, oxidative stress contributes to inflammation and endothelial dysfunction. In cognitive impairment and dementia, oxidative stress damages neurons and promotes neurodegeneration. In cancer, oxidative stress promotes carcinogenesis through DNA damage and inflammation. Oxidative stress is also linked to sarcopenia and frailty, with biomarkers such as protein carbonyl, AGEs, and 8-oxodG indicating oxidative damage. Antioxidant biomarkers like MPO and ADMA are used to assess oxidative stress and its impact on health. Antioxidant therapies, including vitamins, CoQ10, selenium, and polyphenols, may help reduce oxidative stress, but their efficacy is still under investigation. The review highlights the importance of oxidative stress in aging and disease, emphasizing the need for further research to develop effective antioxidant therapies.Oxidative stress, aging, and diseases: A review Oxidative stress arises from an imbalance between reactive oxygen and nitrogen species (RONS) and antioxidant defenses. Aging is characterized by progressive loss of tissue and organ function, and oxidative stress is implicated in age-related conditions such as cardiovascular diseases (CVDs), chronic obstructive pulmonary disease (COPD), chronic kidney disease (CKD), neurodegenerative diseases, and cancer. Oxidative stress biomarkers can provide insights into treatment efficacy and guide drug selection. Antioxidant therapy may benefit several diseases, but further research is needed to confirm its effectiveness. Oxidative stress is caused by both endogenous and exogenous sources, including NADPH oxidase, myeloperoxidase, and environmental factors like pollution and drugs. RONS cause oxidative modifications of cellular macromolecules, leading to markers of oxidative stress. Oxidative stress contributes to cellular senescence, which is linked to aging and age-related diseases. The oxidative-inflammatory theory of aging suggests that chronic oxidative stress disrupts homeostasis, leading to inflammation and increased age-related morbidity and mortality. Oxidative stress is involved in CVDs, diabetes, COPD, CKD, cognitive impairment, and cancer. In CVDs, oxidative stress contributes to atherosclerosis and vascular dysfunction. In diabetes, oxidative stress accelerates complications. In COPD, oxidative stress leads to lung damage and impaired immune function. In CKD, oxidative stress contributes to inflammation and endothelial dysfunction. In cognitive impairment and dementia, oxidative stress damages neurons and promotes neurodegeneration. In cancer, oxidative stress promotes carcinogenesis through DNA damage and inflammation. Oxidative stress is also linked to sarcopenia and frailty, with biomarkers such as protein carbonyl, AGEs, and 8-oxodG indicating oxidative damage. Antioxidant biomarkers like MPO and ADMA are used to assess oxidative stress and its impact on health. Antioxidant therapies, including vitamins, CoQ10, selenium, and polyphenols, may help reduce oxidative stress, but their efficacy is still under investigation. The review highlights the importance of oxidative stress in aging and disease, emphasizing the need for further research to develop effective antioxidant therapies.