Iron and Your Performance

Iron and Performance One in every 8 women of child-bearing age is anemic. It is more likely that you are, or someone you know is, iron-deficient. Women of reproductive age are among those most vulnerable to iron deficiency. One study found among 166 women, 31% of female athletes and 46% of female non-athletes were iron-deficient.¹

More Fit, Better Mood, Quicker and Smarter?

If you are iron-deficient, you may not notice. But your physical performance or cognitive capabilities can be adversely affected. As early as 1988, researchers found that iron-deficiency in adolescent runners impaired their endurance.² Consider more current research:

A 2002 study found that iron supplementation would improve aerobic fitness among marginally iron-depleted women.³
A 2007 study found that iron-sufficient women performed better on cognitive tasks, and completed them faster than did the women with iron-deficient women. Furthermore, researchers learned that the severity of anemia affects processing speed, and the severity of iron-deficiency affects accuracy of cognitive function.⁴
The US Army Research of Institute of Environmental Medicine recently found that iron status is affected by basic combat training, and that iron supplementation improved moods and resulted in faster running time.⁵

According to Israeli researchers, women athletes have additional reasons for iron or blood loss such as increased perspiration, plasma expansion, and occasionally malnutrition. They recommend iron supplements as it is nearly impossible to refill the iron stores through diet alone.⁶

Iron-Deficiency vs. Anemia

Inadequate iron intake and depleted iron stores cause iron-deficiency. Iron-deficiency is the first phase before iron-deficiency anemia.

Diagnosis is made by a complete blood count (CBC) test. A CBC measures hemoglobin (grams/deciliter) and hemocrit levels. Anemic ranges of hemoglobin and hemacrit values for adults are:

Age/Sex (yrs)	Hemoglobin (g/dL)	Hemacrit %
Adult Men	<13.0	<39
Non-Pregnant Women	<12.0	<36
Pregnant Women	<11.0	<33

An iron status test will measure ferritin which serves as an index of body iron stores. Normal ranges of ferritin (nanograms per milliliter or micograms per liter) are:

Adult Men: 18-270 ng/mL or 18-270 mcg/L
Adult Women: 18-160 mg/mL or 18-160 mcg/L

The lower the ferritin level, even within the "normal" range, the more likely it is that you do not have enough iron. If you think you may be iron-deficient, alter your diet, talk with your health professional, and consider iron supplements.

Sources:

1. W.L. Risser, E.J. Lee, H.B. Poindexter et al, "Iron Deficiency in female athletes: its prevalence and impact on performance," Medical Science Sports Exercise April 1988: 116-21.
T.W. Rowland, M.B. Deisroth, G.M. Green, et al, "The effect of iron therapy on the exercise capacity of nonanemic iron-deficient adolescent runners," American Journal of Diseases of Children February 1988: 165-9.
T. Brownlie IV, V. Utermohlen, P.S. Hinton, et al, "Marginal iron deficiency without anemia impairs aerobic adaptation among previously untrained women," American Journal of Clinical Nutrition April 2002: 734-742.
L.E. Murray-Kolb and J.L. Beard, "Iron treatment normalizes cognitive functioning in young women," American Journal of Clinical Nutrition March 2007: 778-87.
JP McClung, JP Karl, SJ Cable, et al, "Randomized, double-blind, placebo-controlled trial of iron supplementation in female soldiers during military training: effects on iron status, physical performance, and mood," American Journal of Clinical Nutrition July 2009: 124-131.
S. Portal, M. Epstein, G. Dubnov, "Iron deficiency and anemia in female athletes – causes and risks," Harefuah October 2003: 698-703.