cruciferous vegetables are antioxidants
A common trait of cruciferous vegetables is that they are high in Vitamin C. Vitamin C is a powerful antioxidant.
Oxidation is a chemical process in oxygen binds with other molecules to form new compounds. Oxygen is a very reactive atoms, seeking 2 electrons to fill its outer shell. A common example is burning firewood. The heat and light are by-products of the oxidation. Wood is an organic substance, which means it consists of chains of carbon atoms. The oxygen binds with the carbon in the wood, altering it to become carbon dioxide and monoxide and charcoal. The heat and light are the energy released when the electrons in the outer shells of atoms change positions.
Oxygen has a similar affect in our bodies. It binds with other molecules in the tissues of the body, disrupting or damaging organs and cells. Oxygen and other reactive substances are called free radicals.
Antioxidants are substances which are also high reactive. They will readily provide the oxygen atoms with extra electrons. If you recall your chemistry, an atom can get a complete outer shell by either gaining or losing electrons. Antioxidants lose electrons. Thus antioxidants prevent oxidation by neutralizing the free radical. So, by consuming vitamin C, the free radicals in your blood stream are neutralized.