25(OH)D levels in trained versus sedentary university students at 64° north

ABSTRACT

Purpose: 25-hydroxyvitamin D (25[OH]D) deficiency is associated with compromised bone mineralisation, fatigue, suppressed immune function and unsatisfactory skeletal muscle recovery. We investigated the risk of 25(OH)D insufficiency or deficiency in endurance athletes compared to sedentary non-athletes living at 64° north.

Methods: University student-athletes (TS) and sedentary students (SS) volunteered to participate in this study. TS engaged in regular exercise while SS exercised no more than 20 minutes/week. Metabolic Equivalent of Task (MET) scores for participants were determined. Vitamin D intake was assessed using the National Cancer Institute’s 24-hour food recall (ASA24). Fasting plasma 25(OH)D levels were quantified via enzyme-linked immunosorbent assay.

Results: TS reported higher activity levels than SS as assessed with MET-minutes/week and ranking of physical activity levels (p < 0.05). The reported mean daily intake of vitamin D was higher in TS compared to SS (p < 0.05) while 25(OH)D plasma levels were lower in TS than in SS (p < 0.05). In total, 43.8% of the TS were either insufficient (31.3%) or deficient (12.5%) in 25(OH)D, while none of the SS were insufficient and 13.3% were deficient.

Conclusion: TS are at increased risk of 25(OH)D insufficiency or deficiency compared to their sedentary counterparts residing at the same latitude, despite higher vitamin D intake.

KEYWORDS:

• Cholecalciferol
• exercise
• endurance athletes
• high latitude
• vitamin D

Acknowledgements

We would like to thank Scarlett Hopkins of the University of Alaska Fairbanks for conducting blood draws and the Center for Alaska Native Health Research for the use of clinic space. We extend our thanks to student Evelyn Evans of the Rural Alaska Honors Institute for laboratory assistance. The work reported in this publication was supported by the National Institute of General Medical Sciences of the National Institutes of Health (NIH) under three linked award numbers: RL5GM118990, TL4GM118992 and 1UL1GM118991. Additionally, sample collection was supported by an Institutional Development Award (IDeA) from the National Institute of General Medical Sciences of the NIH under grant number P20GM103395. All results of the study are presented clearly, honestly and without fabrication, falsification or inappropriate data manipulation.

Disclosure statement

The authors declare no conflict of interest. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.

Additional information

Funding

This work was supported by the National Institute of General Medical Sciences (grant numbers RL5GM118990, P20GM103395, 1UL1GM118991 and TL4GM118992).