Q: My diet tends to include a lot of iron. Is it possible to get
too much?
A: Some Americans need iron supplements. Others get more iron
than they need, and sometimes the extra iron causes damage. How do
you know if you need more iron, or need to avoid iron?
Q: My diet tends to include a lot of iron. Is it possible to get too much?
A: Some Americans need iron supplements. Others get more iron than they need, and sometimes the extra iron causes damage. How do you know if you need more iron, or need to avoid iron?
“Do you have iron-poor, tired blood?” Asked the Geritol ads from the 1960s. Then they offered a supplement sure to help anyone tired from working, cleaning or taking care of children. It could even improve marriages and sex lives. Geritol’s parent company ended up paying a hefty fine for false advertising, but the slogan still holds wall space in the mental hallways of many. But just how important is iron?
Very. Iron forms part of hemoglobin, the molecule that enables your red blood cells to transport oxygen throughout the body, from toes to tonsils. The most common consequence of iron deficiency is anemia, a shortage of hemoglobin. Iron also assists in the formation of muscle cells and a number of proteins and enzymes.
Normally, the body does a remarkable job of reusing and saving iron. It loses only one to two milligrams (mgs) each day through sweat and skin and other tissues that the body sloughs off. That’s about how much most people need to absorb from their diet. Recommendations for daily intake are higher because only a fraction of the iron we eat is absorbed.
The body does store iron, so stored levels tend to increase with age. With these reserves to draw upon, older people – at least in the United States – usually needn’t worry about a shortage of iron.
About 1 in every 3 people in the world may need additional iron because of iron-poor diets. Only about 5 percent of Americans are deficient because of iron added to packaged foods and a higher consumption of meat, poultry and fish. Even in this country, however, iron deficiency can be a problem for younger women because they have significant amounts of blood loss from menstruation: when you lose blood, you lose the iron in the blood. Children are vulnerable, too, because they’re growing so fast.
About 1 in every 200 people has just the opposite problem: iron overload caused by an inherited condition called hemochromatosis (HE-moe-KRO-moe-TOE-sis) that causes the body to absorb too much iron. Levels can get high enough to cause liver and pancreatic damage. The condition is often controlled by having blood drawn regularly, to remove iron from the body.
There is some evidence that high iron intake might be a more general problem. Research has linked high iron intake to disorders of the nervous system. One study found that people with high iron intake have an increased risk of developing Parkinson’s disease. Researchers have also reported links between iron and heart disease. These findings have been contradicted by others, however, so the connections are still unclear.
When you eat meat, poultry or fish, you’re consuming iron that’s readily absorbed because it’s already conveniently packaged in hemoglobin and an oxygen-carrying protein in muscle fibers that is similar to hemoglobin. The iron in plant and dairy foods and added to some cereals and multivitamins is not as easily absorbed.
A form of iron found in soybeans is absorbed well. This form might be an inexpensive way to improve dietary iron intake. Products made from whole soybeans, like soy milk and soy butter, are rich in this type of iron but tofu, prepared in the traditional way, has less because it’s made from hulled soybeans.
Iron absorption can be dramatically affected by other compounds and nutrients. A compound found in spinach cocoa, and some nuts interferes with it, as do the tannins in tea. But
vitamin C boosts iron absorption.
The bottom line is that if you are a woman who has regular heavy menstrual periods, or who is pregnant, you should have your blood count and blood iron checked periodically. The only reason for a man or a non-pregnant woman to take iron each day is if tests show that their blood iron level is low. Taking a daily iron pill (or liquid) if your iron levels are not low may actually cause harm, especially if you have hemochromatosis and don’t know it. The small amounts of iron in a typical multivitamin tablet probably will not cause harm, except for those with hemochromatosis.
– By the staff at Harvard Medical School
Submit questions to the Harvard Medical School Adviser at www.health.harvard.edu/adviser. Unfortunately, personal responses are not possible. For more consumer health information from Harvard Medical School, please visit www.health.harvard.edu.
