April, 19, 2004 (Washington) -- Even moderate iron deficiency can impair a woman's thinking. But iron supplements appear to help reverse any learning and memory deficits caused by a lack of iron, a new study shows.
The study is one of the first of its kind to link iron deficiency with a slow down in thinking and memory and to show that replacing iron can remedy the deficits. But researchers warn that supplements have no benefit for women with normal iron levels and that women should have their blood levels checked before using them.
Researchers gave a series of learning and memory tests to more than 100 women between the ages of 18 and 35, about half of whom also had mild iron deficiency but without anemia. More severe iron deficiency can cause anemia, known commonly as "low blood counts," which is caused by decreased production of oxygen-carrying red blood cells.
In one test, women were asked to remember a lineup of pictures displayed on a computer screen. On average, those with normal iron levels missed eight questions out of 54, while those with deficiencies missed twice as many, according to Laura Murray-Kolb, PhD, a nutrition researcher at Pennsylvania State University and the study's lead researcher.
"There were in fact differences. The women who were iron deficient did not perform as well as the women who were not deficient," she tells WebMD.
But researchers then gave the iron-deficient women 60 milligrams of elemental iron per day and then measured iron levels to be sure that the pills returned iron levels to normal. After four months, the deficient women performed as well on the tasks as women who started out normal.
Studies in rats have linked iron deficiency to abnormal brain chemical functioning, and Murray-Kolb says that the same mechanism may be at work in women. If iron helps improve the brain's production of chemicals -- such as dopamine and serotonin -- it could help restore faulty learning and memory.
"The good news is that replacement does help return functioning to normal," she says. The study was unveiled at a meeting of the American Physiological Society.
Approximately 20% of women are thought to have chronic iron deficiency. But Murray-Kolb warns that women should have their iron levels checked before running out to buy iron supplements. She stressed that taking extra iron is of no help to women with normal levels. In addition, taking too much iron can lead to problems, such as liver damage.
"I don't think we want to throw a recommendation out there [for women to take supplements]. But for a women to be aware of her iron status is probably a good idea," she says.