What is Iron Overload and Toxicity?
We have seen that absorption of iron is very effectively regulated. This prevents overload of the tissues with iron from diet/supplements in normal healthy individuals. However, an excessive body burden of iron can be produced by greater-than-normal absorption from the alimentary canal, by parenteral injection or by a combination of both. For instance, people with genetic defects develop iron overload as it occurs in idiopathic haemochromatosis. It is a hereditary disorder of iron metabolism characterized by abnormally high iron absorption owing to a failure of the iron absorption control mechanism at the intestinal level.
High deposits of iron in the liver and the heart can lead to cirrhosis, hepatocellular cancer, congestive heart failure and eventual death. African or Bantu siderosis, chronic liver disease, pancreatic insufficiency, shunt haemochromatosis and certain types of refractory anaemia have been found to be associated with iron overload. It has recently been shown that excess iron intake via overuse of iron supplements could pose a possible health risk. Cellular and tissue injury due to free radical reactions appears to be the possible mechanism. Normally iron is bound tightly to the proteins. However, it is possible that excess iron intake permits some iron to be in a free form. Associated complications may include increased risk for bacterial infection, neoplasia, arthopathy, cardiomyopathy and endocrine dysfunction.