When asked to participate in a recent blood drive, several women I know volunteered immediately as donors. To their great surprise, two were turned away -- not because their blood was dangerous to others, but because they were anemic. Both women immediately followed up with their doctors and learned that their anemia was caused by iron deficiency.
A recent report by the federal Centers for Disease Control and Prevention revealed that about 1 in 10 adolescent girls and pre-menopausal women in the United States is iron-deficient. In about half of these cases, the deficiency is severe enough to affect the production and quality of red blood cells, causing anemia.
Iron deficiency is much more common in women of childbearing age than in similarly aged men. That's because women lose significant amounts of iron through their menstrual flow. (In women who have very heavy or prolonged menstrual periods, the loss of iron is particularly high.) Those who fail to compensate for the loss by consuming enough iron -- either through foods or supplements -- will gradually develop iron deficiency and, possibly, anemia.
Iron plays several important roles in the body, but is best known for helping transport oxygen through the blood. Iron is a key component of hemoglobin, a substance in red blood cells that carries oxygen from the lungs to tissues throughout the body.
Without sufficient iron, hemoglobin production and oxygen transportation can be compromised. Nevertheless, many iron-deficient women -- even those with anemia -- show no signs or symptoms. Some, however, do experience fatigue.
Because iron deficiency is so common in the U.S., some medical experts think all women should be screened regularly to detect this problem; other experts say routine testing isn't necessary. The CDC, for example, recommends anemia testing for adolescent girls and women of childbearing age at least every five to 10 years. The U.S. Preventive Services Task Force, on the other hand, believes that such testing is not indicated.
"While we know that screening can identify women with anemia and that iron can correct abnormalities in their blood tests, it's still unclear whether or not treatment does much to make the typical woman with mild anemia feel any better," says Dr. David Atkins, a medical officer with the Agency for Healthcare Research and Quality. "Although treatment makes sense for women with symptoms from more severe anemia, those aren't the ones you find by routinely screening healthy women."
Doctors generally agree, however, that all pregnant women should be screened for anemia, because the demand for iron increases so dramatically during pregnancy and the risk of iron deficiency is so high. The consequences of anemia are also greater during pregnancy: Anemia doubles a pregnant woman's chances of delivering prematurely and triples her chances of having a baby with a low birth weight. Routine screening is considered unnecessary in men and in women after menopause, since the likelihood of deficiency is low.
When iron deficiency is diagnosed, the treatment consists of iron replacement. Ideally, this is accomplished by greatly increasing the amount of iron-rich foods a person eats. The solution is not that simple, however, since the body absorbs only a small amount of the iron from foods. The amount of iron absorbed depends, in part, on the food source. For example, the iron in meat, poultry and fish is two to three times more absorbable than the iron in plant-based foods and iron-fortified food products.
When iron deficiency is severe enough to cause anemia, iron supplements are usually recommended in addition to dietary changes to correct the deficiency more quickly. (A 4-ounce steak contains about 4 milligrams of iron; a typical iron supplement contains as much as 80 milligrams.) Although effective, iron supplements can cause some unpleasant side effects, including nausea and constipation.
And what about the women turned away by the blood bank? They're taking iron supplements and trying to add a little more red meat to their diets. "I haven't eaten so many hamburgers since I was a kid," one said recently. "The next thing you know, they'll be rejecting me because my cholesterol is too high."
Infants need iron in their diets too
During infancy and early childhood, rapid growth increases the body's demand for iron. If that need is not met, the resulting iron deficiency and anemia can have potentially irreversible effects on behavior and development.
While breast-feeding is the best form of nutrition for infants, breast milk contains very little iron, so children who are exclusively breast-fed can develop iron deficiency. To prevent this, supplementary foods containing iron are recommended from about age 4 to 6 months. (Babies born at full term typically have iron stores sufficient to last the first 4 to 6 months of infancy.) Just two servings per day of iron-fortified infant cereal can meet an infant's requirement for iron at this age. Generally, other iron-rich foods, such as plain, pureed meats, can be gradually introduced by age 6 months, as well as foods rich in vitamin C to help improve iron absorption.
Infants who are not breast-fed should be fed iron-fortified infant formula. Some studies have shown that infants who are iron-deficient perform worse in tests of mental and motor development than those who get enough of the nutrient. But because excessive iron can be extremely dangerous for children, iron supplements should be used only under a physician's guidance.
Dr. Valerie Ulene is a board-certified specialist in preventive medicine practicing in Los Angeles. Our Health appears the first Monday of the month.