There may be a common mechanism involved in the development of many chronic diseases. This common factor is the free radical and it's damaging effects on DNA, protein and lipids in the body. Oxygen free radicals are continuously generated in cells exposed to an aerobic (oxygen) environment. They are formed during normal metabolism and can also arise following exposure to environmental factors, for example cigarette smoke and pollution. Free radicals have one or more unpaired electrons and reaction of radicals with non-radicals results in new radicals therefore a chain reaction results. DNA, lipid and protein molecules in the body can be damaged during times of excess oxidative stress when there is either an over production of free radicals or there is a deficiency of antioxidant defence or repair mechanisms. Dietary antioxidants are part of the body's total antioxidant defences against free radical damage and act by donation of an electron to stabilise the free radical.