A cognitive boost from iron or zinc.

Nearly one in 10 U.S. women of reproductive age suffers from iron dificiency, and most of these women are also low on zinc. Studies have shown that a dificiency of either mineral can impair cognitive functioning.

Now, researchers report boosting the memory and reasoning capabilities of 26 iron- and-deficient women with an eight-week regimen of mineral supplementation. At the University of Texas Medical Branch in Galveston, Harold H. Sandstead and a colleague gave the women 30-milligram tablets of iror or zinc, or a tablet of each, every day, along with a general vitamin supplement. For comparison, eight mineral-deficient women and 11 healthy women received only the vitamin supplement.

Women who took either the zinc or iron supplement improved their scores on the Wechsler Memory Test by up to 20 percent, with an average increase of 10 percent, Sandstead says. Those who took only the vitamins showed no change.

Interestingly, women who took the iron-zinc combo did not improve their scores. Sandstead attributes this to the two mineral's ability to cancel each other out, as demonstrated previously in laboratory tests. Iron and zinc also had differing effects on the volunteers' cognition, he says. Iron -- but not zinc -- improved short-term memory of verbal information, and zinc -- but not iron -- improved the ability to associate word pairs.

The results are "certainly remarkable," says psychologist James G. Penland, who studies the link between nutrition and cognitive functioning for the U.S. Department of Agriculture in Grand Forks, N.D. But Penland cautions that the Wechsler Memory Test is not the most sensitive cognitive test.