Randomized, double-blind, placebo-controlled trial of iron supplementation in female soldiers during military training: effects on iron status, physical performance, and mood

Background: Decrements in iron status have been reported in female soldiers during military training. Diminished iron status adversely affects physical and cognitive performance. Objective: We wanted to determine whether iron supplementation could prevent decrements in iron status and improve measures of physical performance and cognitive status in female soldiers during basic combat training (BCT). Design: In this 8-wk randomized, double-blind, placebo-controlled trial, soldier volunteers (n = 219) were provided with capsules containing either 100 mg ferrous sulfate or a placebo. Iron status indicator assays were performed pre- and post-BCT. Two-mile running time was assessed post-BCT; mood was assessed by using the Profile of Mood States questionnaire pre- and post-BCT. Results: The BCT course affected iron status: red blood cell distribution width and soluble transferrin receptor were elevated (P < 0.05), and serum ferritin was lowered (P < 0.05) post-BCT. Iron supplementation attenuated the decrement in iron status; group-by-time interactions (P < 0.01) were observed for serum ferritin and soluble transferrin receptor. Iron supplementation resulted in improved (P < 0.05) vigor scores on the Profile of Mood States post-BCT and in faster running time (P < 0.05) in volunteers reporting to BCT with iron deficiency anemia. Conclusions: Iron status is affected by BCT, and iron supplementation attenuates the decrement in indicators of iron status in female soldiers. Furthermore, iron supplementation may prove to be beneficial for mood and physical performance during the training period. Future efforts should identify and treat female soldiers or athletes who begin training regimens with iron deficiency or iron deficiency anemia. Am J Clin Nutr 2009;90:124-31.