Being fed cow's milk, rather than breast milk, is just one reason why some infants may become iron deficient, according to the U.S. National Library of Medicine. Long-term blood loss and rapid growth are two other possible causes of this condition, which can have a serious impact on babies as they mature. The brain is especially vulnerable to a lack of iron in the body, with youths deficient in this mineral at a higher risk of developing cognitive problems, such as learning difficulties, decreased attention span and reduced alertness.

Recently, researchers from the University of Illinois set out to enhance their knowledge of iron-deficient diets and their impact on infants' cognitive development in a study using neonatal piglets. The baby mammals were chosen because their brains grow very similarly to those of postnatal human infants.

During the study, the piglets were fed one of three diets. Those who were placed in the control group received the recommended levels of iron, while the second and third groups were fed diets that were mildly and severely deficient in iron, respectively. After a few weeks, the piglets were tested in a T-shaped maze and trained to seek out a milk reward.

"Piglets provided the diet severely deficient in iron just didn't learn the task," said Rodney Johnson, the director of the University's Division of Nutritional Sciences and a professor of animal sciences. "It's a T-maze so they have a 50 percent chance of getting it right. Even after 6 days of training, they never performed above chance levels. The piglets given the mildly deficient diet showed intermediate performance, but their performance was not significantly different from that of piglets given the control diet."

If parents are concerned about the level of iron in their children's diet and its impact on their cognitive development, they may want to have them take an IQ test for kids.