Body Fat Percentage and Blood Donation are the Strongest Determinants of Iron Stores in Premenopausal Women Joining the New Zealand Army.

INTRODUCTION: Suboptimal iron status is an issue for women joining the military because of its association with impaired aerobic performance, yet no studies have investigated dietary and non-dietary determinants of iron status simultaneously in this population. The purpose of this study was to explore associations between iron stores, dietary patterns (DPs), and potential non-dietary determinants of iron status in premenopausal women at the commencement of basic military training (BMT) in the New Zealand Army. METHODS: During week 1 of BMT, demographic, body composition, lifestyle, medical history, and dietary data were measured as potential determinants of serum ferritin (SF) in 101 participants. Following univariate analysis, age, body fat percentage, previous blood donation, at least 6 h of exercise per week that raised the heart rate, and a vegetarian DP were analyzed using a multiple linear regression model. RESULTS: An increase in body fat percentage was associated with increased SF (P < .009), although blood donation in the past year decreased SF (P < .011) compared to those participants who did not donate blood. There was no association between SF and a vegetarian DP or hours of exercise per week. The model explained 17.5% of the variance in SF at the commencement of BMT. CONCLUSION: Body fat percentage and blood donation in the past year were the strongest determinants of iron stores in healthy premenopausal women commencing BMT. It is recommended that women joining the New Zealand Army are provided information to maintain or improve their iron status based on these findings. This includes clinical screening of iron status, advice for women considering blood donation, and dietary advice regarding total energy requirements and iron bioavailability.

Iron status and associations with physical performance during basic combat training in female New Zealand Army recruits.

Decreases in Fe status have been reported in military women during initial training periods of 8-10 weeks. The present study aimed to characterise Fe status and associations with physical performance in female New Zealand Army recruits during a 16-week basic combat training (BCT) course. Fe status indicators - Hb, serum ferritin (sFer), soluble transferrin receptor (sTfR), transferrin saturation (TS) and erythrocyte distribution width (RDW) - were assessed at the beginning (baseline) and end of BCT in seventy-six volunteers without Fe-deficiency non-anaemia (sFer 10 mg/l at baseline or end. A timed 2·4 km run followed by maximum press-ups were performed at baseline and midpoint (week 8) to assess physical performance. Changes in Fe status were investigated using paired t tests and associations between Fe status and physical performance evaluated using Pearson correlation coefficients. sFer (56·6 (sd 33·7) v. 38·4 (sd 23·8) µg/l) and TS (38·8 (sd 13·9) v. 34·4 (sd 11·5) %) decreased (P<0·001 and P=0·014, respectively), while sTfR (1·21 (sd 0·27) v. 1·39 (sd 0·35) mg/l) and RDW (12·8 (sd 0·6) v. 13·2 (sd 0·7) %) increased (P<0·001) from baseline to end. Hb (140·6 (sd 7·5) v. 142·9 (sd 7·9) g/l) increased (P=0·009) during BCT. At end, sTfR was positively (r 0·29, P=0·012) and TS inversely associated (r -0·32, P=0·005) with midpoint run time. There were no significant correlations between Fe status and press-ups. Storage and functional Fe parameters indicated a decline in Fe status in female recruits during BCT. Correlations between tissue-Fe indicators and run times suggest impaired aerobic fitness. Optimal Fe status appears paramount for enabling success in female recruits during military training.