In the human body, free radicals are created every day. Free radicals are highly reactive compounds that attack the nearby molecules, make them new radicals and thus lead to chain reactions. Free radicals can arise as a result of exposure to environmental pollutants, smoking, excessive consumption of alcohol, because of infections, stress or aging, and the most common free radicals are reactive oxygene species (ROS). Antioxidants, a group of compounds that come from food or are naturally present in the body, are molecules which can safely interact with free radicals. The aim of this thesis is to describe the dietary antioxidants and the antioxidant sources, like antioxidant foods, that should be part of a balanced nutrition. Unbalanced nutrition leads to reduced destruction of free radicals resulting in oxidative stress, and consequently to various diseases and aging. Daily intake of foods rich in antioxidants and synergistic effect of various antioxidants, results in the full potential of their beneficial effect on the human organism. All of this contributes to the preservation of health and normal life functions.