Iron is a critical nutrient needed to supply oxygen to the cells and tissues and to help produce brain chemicals, amino acids and hormones. Iron deficiency can result in anemia, a condition that causes fatigue, loss of appetite and shortness of breath.

The General Practice Unit at the University of Lausanne in Switzerland found that non-anemic women with unexplained fatigue benefited from iron supplementation. In a double-blind study, 136 women aged 18 to 55 (50% with low iron levels) were given either 80 mg of iron or a placebo daily for four weeks. The women in the treatment group experienced a 29% decrease in fatigue compared to only 13% in the control group. This benefit seemed to only apply to women who had low iron levels to start.

However, iron supplementation is often not well tolerated, especially during pregnancy. Researchers at the Child Nutrition Research Centre at the University of Adelaide in Australia found that supplementing with 20 mg of iron from week 20 of pregnancy until delivery was a well-tolerated prevention strategy. In this double-blind study, 386 pregnant women were given either 20 mg of iron or a placebo daily. Side effects were reviewed at week 24 and 36. At delivery, only 3% of women from the treatment group had iron-deficiency anemia compared to 11% in the control group, and 35% versus 58% were iron deficient. This benefit lasted until six months postpartum. The big surprise was that there was no significant difference in side effects noted by the two groups.

Sources: BMJ. 2003 May 24;326(7399):1124; Am J Clin Nutr. 2003 July;78(1):145-53