Antioxidants protect against oxidative stress by neutralizing free radicals in the body. Free radicals can damage cells, proteins, and DNA, contributing to aging and various diseases. Antioxidants such as vitamins C and E, selenium, and various phytonutrients in fruits and vegetables help mitigate this damage. By reducing oxidative stress, antioxidants play a vital role in enhancing overall health, potentially lowering the risk of chronic conditions like heart disease and cancer.