There is strong indirect evidence that free radical production appears to be an important mechanism of brain injury after exposure to ischaemia and reperfusion. Although significant brain damage occurs during an ischaemic episode, new cerebral damage can occur after reperfusion. One proposed mechanism for the brain damage that occurs during reperfusion involves generation of free radicals. Body defences against free radicals depends on the balance between free radical generation and the antioxidant protective defence system. Many of these protective antioxidants are essential nutrients or have essential nutrients as part of their molecule that has to be obtained from diet.