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Even without anemia, iron may help fatigue

NEW YORK (Reuters Health) – Some women with unexplained fatigue may get a bit more pep from iron supplements – even if they do not have full-blown anemia, a new clinical trial suggests.

Swiss researchers randomly assigned 200 menstruating women with unexplained fatigue to take either 80 mg of iron a day or a placebo.

Over 12 weeks, both groups improved. But women on iron supplements fared better, the researchers reported online July 9th in the Canadian Medical Association Journal.

On average, scores on a standard measure of fatigue fell by nearly half – from about 25 to 13, on a scale of zero to 40 – among women getting the extra iron.

That compared with a 29% decline in fatigue reported by the placebo group, whose average score fell from about 25 to just over 16.

The findings suggest that when a woman’s persistent fatigue cannot be explained by any health condition, low iron should be suspected, according to lead researcher Paul Vaucher, a doctoral candidate at the University of Geneva in Switzerland.

Hemoglobin levels usually don’t fall until the later stages of iron deficiency, Vaucher and colleagues point out. Instead, the researchers suggest looking at blood levels of ferritin.

“This marker will then give a better idea of whether iron load is low or not, even if women are not anemic,” Vaucher said in an email.

All of the women in this study had ferritin levels below 50 mcg/L, which would be considered low to borderline-low.

Since women in the placebo group also improved, the effects of the iron supplement were not huge. They amounted to an extra 3.5 points shaved off a woman’s fatigue score.

“That might seem like a small difference,” said Dr. Christine Gerbstadt, a spokesperson for the Academy of Nutrition and Dietetics who was not involved in the study. But, she said in an interview, the advantage was still statistically significant.

Fatigue is complex and subjective, and women in the placebo group might have improved for a number of reasons, Dr. Gerbstadt noted. Some, for example, may have started getting more sleep and generally taking better care of themselves.

In this study, 35% of iron users reported at least one side effect – though 25% of placebo users did as well.


Can Med Assoc J 2012.