Back in early 2007, I came across a study that I still think about all the time. Here’s the gist: 113 young women, aged 18 through 35, came into the lab at Pennsylvania State University. They took eight different tests on a computer that assessed attention, memory and learning, and their blood was drawn to compare their level of iron to their results on the computer tests. The findings were dramatic: women who were even mildly iron deficient—not yet anemic—scored much lower on many of the tasks and took longer to complete the tasks, than the women whose iron levels were normal. About 10 percent of young women are anemic (because of their monthly loss of iron-rich blood), as are 25 percent of pregnant women. In fact, I’d been told early in my pregnancy that I was slightly anemic, but it never occurred to me that it was much of a problem.
“What that study was able to do for the first time is show that even if you are mildly iron-deficient—you don’t have to be anemic—you have changes in cognitive function,” says John Beard, Ph.D., the iron expert who conducted the study. “It’s a scary thing that people don’t like to hear,” he admits, since a good number of us fall into that slightly iron-deficient gray area.
What really gave me hope was the other half of the study, where Beard put half the women on a slow-release iron supplement containing 60 mg of elemental iron for four months. Unlike the results seen in studies with iron-deficient infants, the women receiving the supplements regained normal cognitive functioning. How? Beard says that since the adult brain is already formed, iron’s primary role is to help feed the brain and build neurotransmitters; some of the brain regions most sensitive to iron deficiency are the prefrontal cortex and the hippocampus, centers of higher intellectual functioning and memory.
In Beard’s study, those women whose blood iron levels improved significantly experienced a five- to seven-fold improvement in cognitive performance. So it is a good bet that part of my problem was lack of iron; my temporary brain boost while I was pregnant could have resulted from the iron-rich prenatal vitamins I took every day. I vowed to do a better job of eating fortified cereals, edamame, clams, white beans, spinach, lentils—and of course meat, which contains the most easily absorbed form of iron. And I started taking a supplement on the side. Better safe than stupid.
Of course, if you’re not iron-deficient, taking more iron isn’t going to do anything to make your brain sharper—and too much iron creates problems of its own, including hemochromatosis (high blood iron), which can lead to liver damage, heart failure or diabetes. Since our bodies are unable to get rid of excess iron (except by bleeding), it makes sense to have your blood iron levels checked before you head to the drugstore for a “brain-boosting” iron pill—especially if you’re a woman past menopause or a man.