Influence of Iron Supplementation on Injury Risk in Basic Combat Training

In a double-blinded study design, female Army basic trainees were randomized into either an iron supplement group (ISG, n=105) or a placebo group (PG, n=103). The ISG consumed 16 mg elemental iron daily. Prior to treatment, measures of physical activity, tobacco use, menstrual status, physical characteristics, body composition, physical fitness, and demographics were obtained. Blood was collected to identify subjects who were iron deficient (ID) or had iron deficiency anemia (IDA). Injury outcomes were obtained from outpatient medical surveillance data. Risk ratios (RR) and 95% confidence intervals (95%CI) were calculated. Cox regression indicated little difference in injury risk between the ISG and PG in multivariate analysis that included significant injury covariates (RR (ISG/PG)=1.14, 95%CI=0.79 1.64, p=0.48). For ID subjects (n=34), univariate Cox regression showed little difference in injury risk between the ISG and PG (RR (ISG/PG)=0.85, 95% CI=0.41-2.10, p=0.85). For IDA subjects (n=43), Cox regression also showed little difference in injury risk between the ISG and PG in multivariate analysis that included significant injury covariates (RR (ISG/PG)=0.87, 95%CI=0.36-2.07, p=0.75). Statistical power analysis indicated that sample sizes of 1,130 ID subjects and 1,680 IDA subjects (in each group) would be needed before these group differences (ISG vs. PG) were statistically significant at the p=0.05 level (power=80%). This study did not support the hypothesis that iron supplementation reduces injuries in BCT.