Iron Deficiency, Poverty, and Cognitive Troubles

Babies who aren’t getting enough iron in their diet do worse on mental-ability tests than babies whose iron needs are being met. In the latest study to confirm that threat to children, researchers find that mental deficits from iron deficiency worsen even into the teen years for children in families of low socioeconomic status.

Betsy Lozoff, a pediatrician at the University of Michigan in Ann Arbor, has been studying this issue for decades. Her new study followed a group of 185 children in an urban community near San Jose, Costa Rica, up to the age of 19.

Lozoff and her colleagues began working with this group in the mid-1980s. The team had invited parents of healthy 1-to-2-year-old babies in the community to have their children participate. The researchers tested the babies’ blood for iron and separated them into groups with chronic iron deficiency or good iron status. In cases of severe lack of iron, or iron deficiency anemia, the researchers treated the babies with supplements of the mineral for 3 months.

Lozoff and her colleagues tested the children’s mental skills as infants and at ages 5, 11 to 14, 15 to 18, and 19 years. The researchers assessed babies by testing such things as whether they could recognize words and imitate an action. Assessments of older children centered on math, reading, and writing.

The researchers determined whether the children came from middle or low socioeconomic backgrounds by considering the educational and occupational status of parents.

Middle-socioeconomic children with good blood-iron status “looked great,” says Lozoff. On a 125-point scale, their mental-test scores were the highest among all the groups throughout the study. But middle class children with chronic iron deficiency consistently lagged 8 to 9 points behind their iron-sufficient, middle class counterparts.

Low-socioeconomic children entering the study with good iron status had mental-test scores close to those of the middle class children with chronic iron deficiency. It was the children with “the double burden” of low status and chronic iron deficiency in infancy that had the lowest scores at the beginning of the study, says Lozoff. Furthermore, their scores worsened over time: They began 10 points below their iron-sufficient socioeconomic peers but fell to 25 points behind by age 19.

“You get a snowball effect,” says Lozoff: The developmental delays due to iron deficiency can become compounded in a family that doesn’t have the resources to help children compensate. The researchers report their findings in the November Archives of Pediatrics and Adolescent Medicine.

The implications are “dramatically important,” comments John L. Beard, a nutritionist who studies neurodevelopment at Pennsylvania State University in University Park. The study indicates that with more educational and economic opportunity, it’s possible to mitigate “about half of the effect of the early life iron deficiency.”

Iron on the brain

A lack of iron can affect babies long before they become anemic. Many studies point to the critical biochemical role that iron plays in brain development and function, says Beard. Researchers have found in rodents that during development of a brain region called the hippocampus, iron deficiency limits the number of connections between nerve cells. “You can hypothesize those cells are getting less information,” says Beard.

Insufficient iron in early life also reduces myelin, the fatty material that surrounds many nerve fibers. With less myelin, there is a reduction in the speed with which information travels along nerve fibers, says Beard. In the case of the muscle-triggering neurons, which are heavily sheathed with myelin, a lack of iron could result in less control of movements, he adds.

These and other changes that iron deficiency causes in the brain “are the things we think are contributing to the long-term cognitive and social-emotional effects we are finding,” says Lozoff. Along with low scores on mental-ability tests, iron-deficient infants display hesitancy and limited interaction with their mothers. “Those things contribute to a child that may be less engaged, or less able to engage, in a social environment,” she says.

“Preventing iron deficiency during the brain’s development is the best way to go,” Lozoff continues. “You can’t count on testing kids for iron deficiency anemia and then giving them iron—you can’t be sure that’s going to fix the problems. The wisest thing is prevention.”

Lozoff and her colleagues are also exploring whether families might be able to help children overcome some of the effects of iron deficiency.

Getting enough

A baby’s diet and her mom’s can produce an iron deficit, notes Lozoff. Breastfeeding provides babies with sufficient iron, but when it’s time to add solid foods to the diet, unfortified baby foods “are very poor sources of iron,” she says. And if the mother is iron deficient during pregnancy, the baby, with less iron stored in its body, “becomes dependent on dietary sources even earlier,” she says.

In the United States and other developed countries, infant formulas, cereals, and other foods have been fortified with iron, which has sharply reduced deficiencies in babies. But the problem continues in the rest of the world, where an estimated 20 to 25 percent of infants exhibit a severe lack of the mineral. In developing countries, if iron-fortified formula is available, it is “a very, very expensive item,” says Lozoff, “so formula is not really an option.”

“We’re hoping there will be some inexpensive and safe ways to get iron into babies in developing countries,” Lozoff says, adding that reducing iron deficiency is part of the United Nations’ Millennium Development goals.

But Lozoff also cautions, “it’s not that you should give the baby many more vitamins with iron, because too much isn’t good either—you should only use as much as directed, in a routine vitamin or as a doctor has suggested.”

Aimee Cunningham is the biomedical writer. She has a master’s degree in science journalism from New York University.

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