Open Access
CC BY-NC-ND 4.0 · Sports Med Int Open 2018; 02(05): E148-E156
DOI: 10.1055/a-0669-0791
Training & Testing
Eigentümer und Copyright ©Georg Thieme Verlag KG 2018

Predictive Factors for Vitamin D Concentrations in Swiss Athletes: A Cross-sectional Study

Simeon Joel Zürcher
1   Epidemiology, Biostatistics and Prevention Institute, University of Zürich, Zürich, Switzerland
,
Andrea Quadri
2   Spital Bulach, Internal Medicine, Bulach, Switzerland
,
Andreas Huber
3   Kantonsspital Aarau, Labaratory Medicine, Aarau, Switzerland
,
Lothar Thomas
4   Klinikum der Johann-Wolfgang-Goethe Universität, Central laboratory for Clinical Chemistry and Hematology, Frankfurt am Main, Germany
,
Graeme Leonard Close
5   LJMU, Sports Science, Liverpool, United Kingdom of Great Britain and Northern Ireland
,
Saskia Brunner
3   Kantonsspital Aarau, Labaratory Medicine, Aarau, Switzerland
,
Patrik Noack
6   Medbase Abtwil, Swiss Olympic Medical Center, Abtwil, Switzerland
,
Boris Gojanovic
7   Hopital de la Tour, Swiss Olympic Medical Center, Meyrin, Switzerland
,
Susi Kriemler
1   Epidemiology, Biostatistics and Prevention Institute, University of Zürich, Zürich, Switzerland
› Author Affiliations
Further Information

Publication History

received 20 March 2018
revised  13 July 2018

accepted 18 July 2018

Publication Date:
25 September 2018 (online)

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Abstract

Vitamin D concentrations corresponding to 75 nmol/L 25(OH)D have been associated with maintained muscle function, growth and regeneration, optimal bone health and immunology in athletes. The objective of this study was to investigate the prevalence and predictors of insufficient 25(OH)D concentrations in athletes. Six hundred three Swiss athletes were assessed. 25(OH)D was analysed by high-performance liquid chromatography (HPLC). A standardized questionnaire was used to gather information about potential predictors for 25(OH)D concentrations; 50.5% showed insufficient 25(OH)D concentrations. Differences in predicted probability of insufficient 25(OH)D were found for those vitamin D supplemented (42%) versus not supplemented (52%), in those performing indoor (58%) versus outdoor sports (43%), and during the sun-deprived seasons of fall (49%), winter (70%) and spring (57%) compared with summer (17%). Higher BMI z-scores and age were associated with higher 25(OH)D concentrations. In conclusion, insufficient 25(OH)D concentrations were common among athletes especially at a younger age, among those not supplemented, in athletes who trained indoors, and during the sun-deprived seasons. Because the prevalence of insufficient 25(OH)D concentrations in this study was high, regular supplementation in athletes may be indicated, except perhaps during the summer season. Further research is needed to determine which 25(OH)D concentrations lead to optimal health and performance in athletes.

Supporting Information