Oxidative Stress and Vitamins

Oxidative stress, resulting from the excessive production of free radicals and reactive oxygen species (ROS) or the inadequacy of an organism's antioxidant defense mechanisms in living systems, can cause permanent damage to cellular lipids, proteins, and DNA. This plays a significant role in the pathogenesis of many chronic diseases, particularly cancer, diabetes, cardiovascular diseases, and neurodegenerative disorders such as Alzheimer's and Parkinson's disease. However, low to moderate levels of physiological ROS production (oxidative estrous stress) are critical for maintaining cellular signaling, immune responses, and redox homeostasis.Primary antioxidant vitamins (vitamin C, vitamin E, and vitamin A/carotenoids) stand out due to their ability to directly scavenge reactive species, interrupt lipid peroxidation chain reactions, and activate cellular antioxidant gene expression pathways such as Nrf2. Vitamin C functions as a direct scavenger in aqueous environments, while vitamin E provides protection within cell membranes. Furthermore, these vitamins create a synergistic defense network by regenerating each other from their oxidized forms. However, despite strong protective evidence from in vitro studies and animal models, clinical trials have revealed a complex picture known in the literature as the “antioxidant paradox.”.Current clinical and epidemiological evidence demonstrates that holistic dietary patterns rich in natural phytochemicals and vitamins, such as the Mediterranean diet and the DASH diet, are significantly more effective and safer in reducing oxidative stress and systemic inflammation biomarkers (CRP, IL-6, TNF-α) than isolated and high-dose synthetic supplements. Furthermore, understanding nutrigenomics and the disease-specific molecular mechanisms underlying various pathologies makes it possible to develop antioxidant strategies tailored to individuals' genetic profiles.This review article aims to identify both the beneficial and harmful aspects of oxidative stress, discuss the therapeutic potential of primary antioxidant vitamins and pro-oxidant risks in light of current clinical findings, and comprehensively present next-generation disease prevention strategies emphasizing lifestyle changes, validation of reliable biomarkers, and modern nutrigenomic approaches rather than relying on a single nutritional supplement.