When you think of people with iron problems you usually think iron deficiency. However you can have a problem if you have too much iron in your body. This problem is called iron overload. If there is too much iron in your body the high absorption can lead to oxidation rancidity in the tissues which can increase the possibility of heart disease and cancer.
If you are on an iron supplement and are worried about the iron you are consuming, just use common sense and take the doses that are on the package. There are restrictions from the manufacturer that govern the dosage for iron supplements, because excess iron can be toxic.