A certain amount of iron in one's diet is crucial for good health; in addition to it being a key component of the hemoglobin in red blood cells, the body needs iron to create myoglobin for muscles and to produce white blood cells. It also plays an important role in biochemical processes to produce energy. Adult women need 12-15 milligrams of iron a day, men need 8-15 milligrams, and children need about 10.
Dietary iron deficiency is the main cause of anemia. The National Institutes of Health estimates that 20% of women, 50% of pregnant women, and 3% of men are iron deficient. Women suffer more from chronic iron deficiency due to regular iron loss from menstruation.
Typical syptoms of iron deficiency include fatigue, bad temper, pale complexion, brittle nails, and weakness. Low-level deficiency may cause no obvious symptoms. Children with iron deficiency have been found to suffer from learning problems, attention deficits, and growth problems, so it's especially important that kids get the iron they need. Foods that are naturally rich in iron include beans and peas, meats (especially red meats), dark green leafy vegetables, blackstrap molasses, and whole grains. Eating foods rich in vitamin C (such as orange juice) in the same meal helps your body absorb the iron.
However, if one consumes much past the recommended daily allowance for one's age, size, and activity level, this mineral becomes unhealthy and even outright poisonous.
There are over 3,500 cases of acute iron poisoning in the the U.S. alone each year. Just a few iron-containing supplement pills can be deadly to an infant or small child: a fatal dose can be 600 milligrams or more. Acute iron poisoning first causes irritation and ulceration of the stomach lining. Once the blood gets loaded with the excess iron, it causes widespread damage to the heart, kidneys, liver, brain, and lungs. The treatment for iron poisoning is to give the victim a chelation agent intravenously.
Lower doses of iron can cause chronic poisoning; this is most often seen in people who have a genetic tendency toward storing excessive amounts of iron (hemochromatosis). Some people with chronic iron poisoning find that their skin turns dark bronze or takes on a grayish hue. People may also suffer from fatigue, upset stomach, and intestinal pain. Eventually, chronic poisoning damages the internal organs, particularly the spleen, liver, and kidneys (the kidney damage causes a type of diabetes known as "bronze diabetes").
But even lower amounts of excess iron can cause subtle damage to the heart.
In the early 90s, medical researchers found that, in middle-aged men, having excessive stores of iron, as indicated by the presence of the protein ferritin in the blood serum, increases the risk of developing ischemic heart disease (IHD) which leads to heart attacks.
Iron evidently promotes the creation of free radicals, and free radicals promote the oxidation of lipids, and oxidized lipids are thought to cause hardening of the arteries (atherosclerosis). The researchers also found a link between elevated levels of ferritin and the consumption of meat, a typically iron-rich food.
The significance of this study is that men (and postmenopausal women) who consume large quantities of iron-rich foods could be putting themselves at risk of developing heart disease. Also, people with hemochromatosis are at risk even if they consume little iron-rich food.
So in order to reduce the risk of heart disease, many older people might need to cut back on iron intake, and it may be further necessary to actively remove iron in some people. "Active removal" might involve such things as prescribing chelating agents or perhaps even bleeding the patient.
People who get too much iron because of genes or diet can do a couple of things to keep themselves healthy:
- Donate blood on a regular basis if your health allows
- Don't consume iron-rich foods along with vitamin C, as the vitamin vastly improves absorbtion of the mineral
- Drink tea -- the tannins in tea block iron absorbtion
- Drink cranberry juice -- an oxalate in the juice also inhibits iron absorbtion
- Get regular vigorous exercise. Exercise provides the double benefit of improving the heart's fitness and increasing iron excretion.
Sources: personal research notes and various Medline articles