Original Article

European Journal of Clinical Nutrition (2016) 70, 1009–1014; doi:10.1038/ejcn.2016.133; published online 27 July 2016

Minerals, trace elements, Vit. D and bone health

The impact of 1-year vitamin D supplementation on vitamin D status in athletes: a dose–response study

E M P Backx1, M Tieland1, K Maase2, A K Kies3, M Mensink1, L J C van Loon4 and L C P G M de Groot1

  1. 1Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands
  2. 2Netherlands Olympic Committee*Netherlands Sports Confederation (NOC*NSF), Arnhem, The Netherlands
  3. 3DSM Biotechnology Center, Delft, The Netherlands
  4. 4NUTRIM School of Nutrition and Translational Research in Metabolism, Maastricht University, Maastricht, The Netherlands

Correspondence: Professor LCPGM de Groot, Division of Human Nutrition, Wageningen University, Bomenweg 4, P.O. Box 8129, NL-6700EV Wageningen, The Netherlands. E-mail: Lisette.deGroot@wur.nl

Received 6 October 2015; Revised 23 May 2016; Accepted 24 June 2016
Advance online publication 27 July 2016





To assess the prevalence of vitamin D deficiency in Dutch athletes and to define the required dosage of vitamin D3 supplementation to prevent vitamin D deficiency over the course of a year.



Blood samples were collected from 128 highly trained athletes to assess total 25(OH)D concentration. Of these 128 athletes, 54 male and 48 female athletes (18–32 years) were included in a randomized, double blind, dose–response study. Athletes with either a deficient (<50nmol/l) or an insufficient (50–75nmol/l) 25(OH)D concentration were randomly assigned to take 400, 1100 or 2200 IU vitamin D3 per day orally for 1 year. Athletes who had a total 25(OH)D concentration above 75nmol/l at baseline continued with the study protocol without receiving vitamin D supplements. Serum total 25(OH)D concentration was assessed every 3 months, as well as dietary vitamin D intake and sunlight exposure.



Nearly 70% of all athletes showed an insufficient (50–75nmol/l) or a deficient (<50nmol/l) 25(OH)D concentration at baseline. After 12 months, serum 25(OH)D concentration had increased more in the 2200 IU/day group (+50±27nmol/l) than the sufficient group receiving no supplements (+4±17nmol/l; P<0.01) and the 1100 IU/day group (+25±23nmol/l; P<0.05). Supplementation with 2200 IU/day vitamin D resulted in a sufficient 25(OH)D concentration in 80% of the athletes after 12 months.



Vitamin D deficiency is highly prevalent in athletes. Athletes with a deficient or an insufficient 25(OH)D concentration can achieve a sufficient 25(OH)D concentration within 3 months by taking 2200 IU/day.

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