The study, the first to systematically examine the impact of iron supplementation on cognitive functioning in women aged 18 to 35 (average age 21), was presented at Experimental Biology 2004, in the American Society of Nutritional Sciences' scientific program. Dr. Laura Murray-Kolb, a postdoctoral fellow in the lab of Dr. John Beard, says the study shows that even modest levels of iron deficiency have a negative impact on cognitive functioning in young women. She says the study also is the first to demonstrate how iron supplementation can reverse this impact in this age group.
Baseline cognition testing, looking at memory, stimulus encoding, retrieval, and other measures of cognition, was performed on 149 women who classified as either iron sufficient, iron deficient but not anemic, or anemic. All of the women underwent a health history, and the research design controlled or took into account any differences in smoking, social status, grade point average, and other measures. The women were then given either 60 mg. iron supplementation (elemental iron) or placebo treatment for four months. At the end of that period, the 113 women remaining in the study took the same task again.
On the baseline test, women who were iron deficient but not anemic completed the tasks in the same amount of time as iron sufficient women of the same age, but they performed significantly worse. Women who were anemia also performed significantly worse, but in addition they took longer. The more anemic a woman was, the longer it took her to complete the tasks. However, supplementation and the subsequent increase in iron stores markedly improved cognition scores (memory, attention, and learning tasks) and time to complete the task.
This finding has great implications, says Dr. Murray-Kolb, because the prevalence of iron deficiency remains at 9 percent to 11 percent for women of reproductive age and 25 percent for pregnant women. In non-industrialized countries, the prevalence of anemia is over 40 percent in non-pregnant women and over 50 percent for pregnant women and for children aged five to 14. According to current prevalence estimates, iron deficiency affects the lives of more than two billion people worldwide.
The findings also are important, say the researchers, because they illustrate the significance of lower amounts of iron deficiency on cognitive functioning, including memory, attention, learning tasks, and time to complete studies.
Some of the known consequences of iron deficiency are reduced physical endurance, an impaired immune response, temperature regulation difficulties, changes in energy metabolism, and in children, a decrease in cognitive performance as well as negative affects on behavior. While iron deficiency was once presumed to exert most of its deleterious effects only if it had reached the level of anemia, it has more recently become recognized that many organs show negative changes in functioning before there is any drop in iron hemoglobin concentration.
Authors of the study are Dr. Murray-Kolb, Dr. Beard, both of the Nutritional Sciences Department at Penn State, and Dr. Keith Whitfield, of Penn State's Biobehavioral Health Department.