Antioxidants and their Impact on Human Health

Abstract The maintenance of cellular and physiological homeostasis relies on a delicate balance between oxidants and antioxidants. When reactive oxygen and nitrogen species (ROS and RNS) are produced in excess due to metabolic and environmental processes, they can induce oxidative stress, accelerate aging, and contribute to the development of chronic diseases, including respiratory, neurological, and cardiovascular disorders. Antioxidants counteract oxidative stress by neutralizing free radicals through mechanisms such as hydrogen atom transfer, electron donation, metal ion chelation, and enzymatic activation. These antioxidants are generally classified into two groups: enzymatic (e.g., glutathione peroxidase, catalase, and superoxide dismutase) and non- enzymatic (e.g., vitamins C and E, carotenoids, flavonoids, glutathione, and uric acid). While antioxidants generally protect against cellular damage, certain conditions, such as the presence of transition metals or high concentrations, can cause them to act as prooxidants. This phenomenon is currently being explored for its potential therapeutic applications in cancer treatment. Antioxidants, which are crucial for maintaining health and preventing disease, are derived from both endogenous synthesis and dietary sources, including fruits, vegetables, nuts, cereals, and beverages. Although the real-world effectiveness of antioxidants is influenced by factors like bioavailability, metabolism, and interactions, their activity is typically evaluated using in vitro tests (such as DPPH, ABTS, FRAP, and ORAC) and in vivo methods. In addition to their health benefits, antioxidants are widely used in industrial applications, cosmetics, and food preservation to prevent oxidation and prolong shelf life. Diets rich in antioxidants are linked to a reduced risk of disease, although the effects of high-dose supplements remain inconsistent. Therefore, the most effective way to promote long-term health and reduce issues related to oxidative stress is to obtain antioxidants through a well-balanced, nutrient-dense diet.