Heme iron comes from animal products, whereas, non-heme iron is found in plants.
The human body regulates non-heme iron absorption, keeping us safe from the ill effects of iron overload. Heme iron is less easily regulated, and as such, can be problematic as it is absorbed faster, and in higher quantities, than non-heme iron. It is because of this bulldozer effect that most people are under the impression that iron from meat is superior, however, more is not always better.
Unlike other nutrients which are discarded through urine/feces when not needed, iron sticks around and is stored by the body. Women are able to release some of the excess stores through menstruation, however, this advantage is lost once menopause occurs. Excess iron is one of the culprits behind several degenerative diseases, including, but not limited to, arthritis, diabetes, cancer, and heart disease.
From Iron metabolism, free radicals, and oxidative injury (Emerit, 2001):
“In developed countries, few, if any, people die of iron deficiency, but an excess of iron storage could impose additional risks on many types of diseases. In American males, the iron stores increase almost linearly with age. Females, after menopause, accu- mulate iron at a rate comparable to that of males. It has been suggested that it is this difference in levels of stored iron that accounts for the gender difference of the mortality statistics for ischemic heart disease.”
Iron accumulates in the brain as people age and is often implicated in neurodegenerative disease as a result. Iron chelation was found to reduce age related dysfunctions.
It is not difficult to check whether your body has accumulated too much stored iron. The following set of tests will check for both iron deficiency and iron overload. The more general hemoglobin and hematocrit tests are not sufficient. Although general guidelines are given here, the tests should be interpreted by your doctor:
The serum-iron value is divided by the TIBC. The result should be between 16 to 50 percent for women and 16 to 62 percent for men. Results above these norms indicate excess iron. Results below these norms indicate iron deficiency. A further test sometimes used to check for iron deficiency is the red cell protoporphyrin test. A result greater than 70 units is considered abnormal. If two of these three values (serum ferritin, serum iron/TIBC, and red cell protoporphyrin) are normal, iron-deficiency anemia is not likely. Serum iron and TIBC should be measured after fasting overnight.
Unfortunately, the body has no way to rid itself of excess iron. The only way to predictably reduce excessive iron stores is by donating blood. Thus, this altruistic act can have health benefits for the donor as well.