Iron, zinc, free radicals and oxygen in tissue disorders and cancer control.

Evidence is presented supporting the argument that various tissue disorders are the result of iron becoming decompartmentalized. In healthy cells, vital molecules are protected from the action of decompartmentalized iron by the presence of zinc. This protection is particularly important during processes leading to cell division. Should excessive decompartmentalization occur and this protective mechanism become overloaded or should it be weakened by ill health, damaging oxidative free-radical reactions may take place. If these are extensive, death may result. When they are only limited, possibly owing to a low oxygen tension or the presence of copper or a carcinogen, the cell may survive but cancer may result. This 'antioxidant' theory of cancer may provide a unifying mechanism for the action of many carcinogenic agents. Carcinogens are considered to be activated not only by the more usually accepted enzymic pathways but by free-radical reactions, catalysed by iron, in the vicinity of critical sites.