In the U.S., iron fortification of infant formula was begun 30 years ago, and iron-deficiency anemia was drastically decreased. However, about 20 percent to 25 percent of all infants in the world have iron-deficiency anemia, and many more have iron deficiency that is not severe enough to cause anemia. The investigators hypothesize that the differences in nerve conduction are due to problems in myelination, because iron is required for normal myelination. The myelin sheath, which acts like the casing of a sausage around the nerve, allows for more speedy transmission of signals from the brain to the rest of the body or from the periphery back to the brain. Without myelin, signals cannot be transmitted as efficiently.
Much myelin formation takes place early in a child's life.
All of the children were full-term babies weighing at least 6 pounds 12 ounces. All children were from similar communities. Chile was chosen as the study site because it was one of the few places in the world where there was a very sophisticated infant neurophysiology laboratory, but also a high prevalence of iron deficiency in infants, Lozoff explains. In Chile, Cecilia Algarin, M.D., and Patricio Peirano, M.D., Ph.D., of the Laboratory for Sleep and Neurobiology at the Institute of Nutrition and Food Technology, University of Chile, headed the actual neurophysiologic studies. Each child was given two tests that provide measures of the integrity of these sensory systems.