Antioxidant is a common term for a large and diverse group of molecules which can react with and neutralize unstable molecules known as free radicals, thereby protecting an organism against the harmful and damaging effects induced by these free radicals.

Antioxidants may act in several ways: they may stop the free radical from forming in the first place, absorb the energy of the produced free radicals, or interrupt an oxidizing chain reaction to minimize the damage caused by free radicals. Well-known examples of antioxidants include vitamins C, E, and A, selenium, beta-carotene, and polyphenols (flavonoids) from natural sources. Scientific studies have suggested several beneficial health effects of antioxidants, but excess supplementation or abuse may result in opposite or harmful effects. Antioxidants are provided by a healthy diet that includes a variety of fresh fruits and vegetables.

In recent years, dietary antioxidants and their potential beneficial effects have gained more and more attention not only in the media, but also in the scientific community. A better understanding of the chemical and biological effects of (natural) antioxidants in food and food-ingredients will contribute to a better awareness of the impact of antioxidants on human health. Acquiring knowledge about the health effects of antioxidants will benefit consumers as well as producers of food and food-ingredients. In addition, animal welfare and veterinary practice will also gain advantages from antioxidant science. A scientific contribution to the unraveling of the complex mechanisms of action and the specific effects of antioxidants is a major goal of ORAC Europe.