Putative role of dietary trace elements in coronary heart disease and cancer.

Relatively little attention has been given to the role of dietary trace elements in oxidative processes or in the aetiologies of chronic disease processes. Iron and copper are pro-oxidants in vitro, but there is now compelling evidence that adequate body copper status is required to maintain antioxidant defences in vivo. Epidemiological evidence linking measures of high iron nutritional status with both coronary heart disease (CHD) and cancer is accumulating, although there are few mechanisms implicating iron in these disease processes apart from acting as a pro-oxidant. In contrast, low copper nutritional status may produce pro-oxidant effects and experimental evidence, especially from animal models of CHD, suggests that copper has an involvement in disease mechanisms which is much wider than simply an involvement in maintaining oxidant/antioxidant balance. Zinc is considered to have antioxidant effects in vivo but the role of zinc as an antioxidant, or in CHD and cancer processes, is presently unclear. Although selenium has for some time been recognised as an antioxidant nutrient, epidemiological data gathered to date linking this trace element with either CHD or cancer are inconsistent.