Racial Differences in Iron Status throughout the Season in Women Collegiate Soccer Athletes
Bridget A. McFaddena J Inter Soc Sports Nutr 2022 Volume 19, Issue sup1 p27
Background: Iron is an essential trace element involved in a multitude of metabolic processes including oxygen transport and utilization, and therefore may significantly affect exercise capacity. Declines in iron have been shown throughout a season in female collegiate soccer athletes. The purpose of this study was to compare hematological status across races in women collegiate soccer athletes.
Methods: National Collegiate Athletic Association Division I female athletes (N = 28; Mage = 19 ± 1y) were monitored over the course of a soccer season and retrospectively divided into two groups based on race (Black [n = 8] and White/non-Hispanic [n = 19]). Blood draws were performed prior to preseason (S1) as well as weeks 4, 8, & 12 of the season (S2-S4). Athletes were instructed to arrive between 0700-0900 h, 18-24 hours post-game in a fasted, euhydrated state. Serum iron (Fe), percent saturation (%SAT), iron-binding capacity (IBC), ferritin (Fer), transferrin (TfR), and hemoglobin (Hb) were analyzed as indicators of iron status. Mixed effects models were conducted to assess changes over time through the season and examine race-by-time interactions. For each biomarker, area under the curve (AUC) was calculated, and T-tests were conducted to compare differences by race. For all analyses, significance was set at p ≤ 0.05. Effect sizes were determined using Cohen’s d.
Results: Athletes experienced declines in Fe (p = 0.001), %SAT (p = 0.02), Fer (p = 0.05), and Hb (p < 0.001) from baseline (S1). No changes in IBC and TfR were seen from baseline (p > 0.05). No race-by-time interactions were observed across the season, however significant racial differences in hematological status were found. AUC analysis revealed Black players exhibited significantly lower Fe (p = 0.01, d = −1.25), %SAT (p = 0.01; d = −1.1), and Hb (p = 0.01, d = −2.39) compared to White players. No differences were seen with IBC (d = 0.28), TfR (d = 0.32), and Fer (d = −0.47) (p > 0.05) throughout the season.
Conclusions: Female athletes experience significant declines in iron status across a collegiate soccer season which may impact performance. Both Black and White players exhibited similar patterns of decline in markers of hematological status. However, despite similar decreases, Black athletes experienced lower iron levels compared to White athletes throughout the entire season. These values approached clinical criteria for iron deficiency by the end of the season (S4). Further studies are needed to elucidate the mechanisms behind the differences of iron status by race, such as iron metabolism, genetic predisposition, or nutritional disparities, to help inform recommendations and personalized nutrition interventions in order to optimize performance in female athletes.