The paper focuses on the antioxidant properties of plant food products, which are very important for the prevention of many diseases. Fruits, vegetables, oil seeds, cereals, herbs, spices, and tea are characterized more precisely. Some processed food products were selected and described owing to their high antioxidant capacity: juices, drinks, wines, plant fats, vegetable and cereal products. Furthermore, there were characterized bioactive substances in plant-based foods that have antioxidant properties; first of all such as polyphenols, vitamins C and E, and carotenoids. The paper also discusses mechanisms of their action on the basis of available references, and correlations between their concentration & qualitative composition, as well as their multidirectional in vitro and in vivo effects. Those current trends in the food production are highlighted which suggest that synthetic antioxidants can be substituted for natural antioxidants provided from raw plants as their source. In this way, the potential of applying raw plants may be essentially increased.