Researchers found that the systems controlling both hearing and sight in the brain were slower in older children who had iron deficiency anaemia in infancy, HealthScout reports.
"Children with anaemia 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 centre for human growth and development at the University of Michigan in Ann Arbor.
Iron is a mineral necessary for the development of red blood cells. As 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. Center 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 paediatrics at the Children's Medical Centre 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 anaemia 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 anaemia 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 Paediatrics and Paediatric Academic Societies on April 30, 2001.