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Early Iron Lack Causes Later Problems

Hearing, vision affected even if infant is treated for deficiency

FRIDAY, May 4 (HealthScout) -- If you didn't get enough iron as a baby, your hearing and sight may suffer years later even if you were treated for the deficiency, says a new study.

Researchers found that the systems that control both hearing and sight in the brain were slower in older children who had iron deficiency anemia in infancy.

"Children with anemia are still showing slower conduction through both the auditory and visual systems at 3 and 4, even though they were treated for iron deficiency," says the study's author, Dr. Betsy Lozoff, director of the center for human growth and development at the University of Michigan in Ann Arbor.

Iron is a mineral that is necessary for the development of red blood cells, and because it helps the blood carry oxygen properly, it affects many different parts of the body, such as the immune system and muscles. Yet, a shortage of iron is the most common form of nutrient deficiency in the world, according to the U.S. Centers for Disease Control and Prevention.

At birth, most babies are born with an iron reserve. "Full-term infants can last six to nine months, but after that, without iron in their diets, they can become iron deficient," says Dr. Joel Steinberg, professor of pediatrics at the Children's Medical Center of Dallas at the University of Texas Southwestern. Premature infants are at higher risk because they do not have adequate stores of iron.

If babies suffer from iron deficiency, Steinberg says the effects can be immediate. If the lack is severe, it can cause heart problems and make a child more susceptible to infection. Lozoff says other studies have shown that iron deficiency in infancy can cause lower IQ scores, trouble in schoolwork -- including difficulty with writing and math -- and even social problems.

Lozoff, along with researchers from the University of Chile, studied 84 Chilean children who were either 3 or 4 years old -- 41 had had iron deficiency anemia when they were babies, and 43 had not. The kids had all been full-term babies and were from similar communities. The children seemed to be growing normally and were not deficient in any other nutrient.

The researchers gave each child two tests to measure how their brains conducted signals from the auditory and visual systems. Electrodes were placed on the children's scalps to measure their response time to the tests. In one test children had to respond to a clicking sound and in the other to a visual signal.

The tests proved that the reaction time in the kids who had been iron deficient was slower, Lozoff says. "It was only fractions of a second difference," she adds, but statistically the differences were large.

"With our increasingly complex needs, these kinds of subtle effects are a real loss of potential for humans," Lozoff says.

She and her colleagues believe that the lack of iron in infancy disrupts the production of myelin in a child's brain. Myelin sheaths cover nerve cells and help the cells transmit signals more rapidly from the brain to the body or from the body to the brain. Nerve cells can send signals without myelin, but the transmission rate is slower. And, because most myelin is produced when children are still infants, the researchers think the iron shortfall these kids had occurred during a crucial period of myelin production.

"Iron deficiency can really have a cumulative effect as these really fundamental processes are being laid down," Lozoff says.

"I think the data from other studies supports the idea that iron deficiency anemia in the first two years of life results in adverse outcomes in cognitive areas," Steinberg adds.

Lozoff presented her findings at the joint meeting of the American Academy of Pediatrics and Pediatric Academic Societies on April 30, 2001.

What To Do

Iron deficiency is a readily preventable condition. Lozoff points out that in the United States, 20 percent to 25 percent of infants used to be anemic, but that has dropped to fewer than 5 percent since iron was added to formula.

Moms-to-be should take a prenatal vitamin with iron, Lozoff, and those who breast-feed should start giving iron supplements or feeding an iron-fortified baby food around 4 to 6 months of age.

If you're feeding using baby formula, make sure it contains iron, and until the baby is at least 1 year old, don't offer cow's milk. Besides having no iron, it can actually cause intestinal bleeding in infants, which worsens iron deficiency, Steinberg says.

One word of caution, though. Check with your doctor before giving iron supplements to a baby or child because too much of this important mineral can be extremely harmful.

For more information on iron deficiency, go to InteliHealth.

This article from the Centers for Disease Control and Prevention looks at ways to prevent and control iron deficiency, while this article from the Australian Iron Status Advisory Panel examines the causes of iron deficiency.

You also might want to read these HealthScout articles on iron deficiency.

SOURCES: Interviews with Betsy Lozoff, M.D., director of the center for human growth and development and professor of pediatrics, University of Michigan, Ann Arbor; Joel Steinberg, M.D., professor of pediatrics, University of Texas Southwestern, Children's Medical Center of Dallas; abstract from April 30, 2001, presentation to joint meeting of American Academy of Pediatrics and Pediatric Academic Societies
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