The Association between Iron and Vitamin D Status in Female Elite Athletes.

Jadwiga Malczewska-Lenczowska,Olga Surała,Dariusz Sitkowski,Konrad Witek,Beata Szczepańska,Joanna Orysiak

doi:10.3390/nu10020167

Abstract

Vitamin D may influence iron metabolism and erythropoiesis, whereas iron is essential for vitamin D synthesis. We examined whether vitamin D deficiencies (VDD) are associated with reduced iron status and whether progressive iron deficiency (ID) is accompanied by inferior vitamin D status. The study included 219 healthy female (14–34 years old) athletes. VDD was defined as a 25(OH)D concentration < 75 nmol/L. ID was classified based on ferritin, soluble transferrin receptor (sTfR), total iron binding capacity (TIBC) and blood morphology indices. The percentage of ID subjects was higher (32%) in the VDD group than in the 25(OH)D sufficient group (11%) (χ2 = 10.6; p = 0.001). The percentage of VDD subjects was higher (75%) in the ID than in the normal iron status group (48%) (χ2 = 15.6; p = 0.001). The odds ratios (ORs) for VDD increased from 1.75 (95% CI 1.02–2.99; p = 0.040) to 4.6 (95% CI 1.81–11.65; p = 0.001) with progressing iron deficiency. ID was dependent on VDD in both VDD groups (25(OH)D < 75 and < 50 nmol/L). The ID group had a lower 25(OH)D concentration (p = 0.000). The VDD group had lower ferritin (p = 0.043) and iron (p = 0.004) concentrations and higher values of TIBC (p = 0.016) and sTfR (p = 0.001). The current results confirm the association between vitamin D and iron status in female athletes, although it is difficult to assess exactly which of these nutrients exerts a stronger influence over the other.

Highlights

Iron and vitamin D are two essential nutrients which constitute an important worldwide health issue due to their significant roles in biochemistry and simultaneously, the very high risk of deficiency in both of them [1,2].Vitamin D plays a dual role in the human body as a prohormone nutrient and fat soluble vitamin
Logistic regression analysis (Table 3), expressed as the odds ratio (OR), with a 95% confidence interval (95%CI), indicated that in female athletes, vitamin D deficiency was significantly (p = 0.01)
The odds ratios for vitamin D deficiency were significantly higher for those with iron deficiency, and the values of ORs increased along with a decreasing level of ferritin as a criterion for iron deficiency, from 1.75 at a ferritin level of 30 μg/L to 3.56

Summary

Introduction

Iron and vitamin D are two essential nutrients which constitute an important worldwide health issue due to their significant roles in biochemistry and simultaneously, the very high risk of deficiency in both of them [1,2].Vitamin D plays a dual role in the human body as a prohormone nutrient and fat soluble vitamin. Iron and vitamin D are two essential nutrients which constitute an important worldwide health issue due to their significant roles in biochemistry and simultaneously, the very high risk of deficiency in both of them [1,2]. Due to its pleiotropic nature, beyond its influence on bone health, vitamin D demonstrates significant involvement in various gene expression processes and plays key roles in calcium and phosphate metabolism, which are involved in a multitude of physiological and pathophysiological mechanisms [3]. Deficiency in vitamin D is linked to numerous illnesses and pathological conditions, including musculoskeletal health, immunity, cardiovascular disease, cancer and mental health [4], as well as deterioration of athletic performance [5,6,7]. Athletes appear to have a similar risk of vitamin D deficiency as nonathletic subjects from the Nutrients 2018, 10, 167; doi:10.3390/nu10020167 www.mdpi.com/journal/nutrients

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