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Elite Athletes do well with weekly 35,000 IU of Vitamin D – RCT Feb 2017

Efficacy of High-Dose Vitamin D Supplements for Elite Athletes.

Med Sci Sports Exerc. 2017 Feb;49(2):349-356. doi: 10.1249/MSS.0000000000001105.
Owens DJ1, Tang JC, Bradley WJ, Sparks AS, Fraser WD, Morton JP, Close GL.
Research Institute for Sport and Exercise Science, Liverpool John Moores University, Liverpool, UNITED KINGDOM; 2Faculty of Medicine and Health Science, Norwich Medical School, University of East Anglia. Norwich, UNITED KINGDOM; and 3Department of Sport and Physical Activity, Edge Hill University, Ormskirk, UNITED KINGDOM.

  • 12 weekly doses for extremely healthy individuals
  • 35,000 IU was good, 70,000 was slightly, but not statistically better

See also VitaminDWiki


Response to weekly 35K and 70K for 12 weeks


Supplementation with dietary forms of vitamin D is commonplace in clinical medicine, elite athletic cohorts, and the general population, yet the response of all major vitamin D metabolites to high doses of vitamin D is poorly characterized. We aimed to identify the responses of all major vitamin D metabolites to moderate- and high-dose supplemental vitamin D3.

A repeated-measures design was implemented in which 46 elite professional European athletes were block randomized based on their basal 25[OH]D concentration into two treatment groups. Athletes received either 35,000 or 70,000 IU·wk vitamin D3 for 12 wk, and 42 athletes completed the trial. Blood samples were collected for 18 wk to monitor the response to supplementation and withdrawal from supplementation.

Both doses led to significant increases in serum 25[OH]D, and 1,25[OH]2D3. 70,000 IU·wk also resulted in a significant increase of the metabolite 24,25[OH]2D at weeks 6 and 12 that persisted after supplementation withdrawal at week 18, despite a marked decrease in 1,25[OH]2D3. Intact parathyroid hormone was decreased in both groups by week 6 and remained suppressed throughout the trial.

High-dose vitamin D3 supplementation (70,000 IU·wk) may be detrimental for its intended purposes because of increased 24,25[OH]2D production. Rapid withdrawal from high-dose supplementation may inhibit the bioactivity of 1,25[OH]2D3 as a consequence of sustained increases in 24,25[OH]2D that persist as 25[OH]D and 1,25[OH]2D concentrations decrease. These data imply that lower doses of vitamin D3 ingested frequently may be most appropriate and gradual withdrawal from supplementation as opposed to rapid withdrawal may be favorable.

PMID: 27741217 DOI: 10.1249/MSS.0000000000001105

 Download the PDF from Sci-Hub via VitaminDWiki

Vitamin D Council review of the study includes some details from the PDF

  • None of the participants experienced adverse side effects from supplementation.
  • Average baseline 25(OH)D levels of the participants was 34 ng/ml.
  • Both supplement doses provided a significant increase in serum 25(OH)D and 1,25(OH)2D3 (p = 0.008).
  • Four weeks after withdrawal from supplementation, the 25(OH)D levels in group 1 returned to levels similar to baseline, whereas group 2 did not (p = 0.007).
  • Group 2 experienced a significant increase in 24,25-hydroxylase at weeks 6 and 12. This remained elevated at week 18, despite the subsequent decrease in 1,25(OH)2D3 at week 12 (p < 0.0001).
  • As suspected, intact parathyroid hormone was decreased in both groups by week 6, which remained throughout the duration of the study.

Attached files

ID Name Comment Uploaded Size Downloads
9355 70K 35K.jpg admin 16 Feb, 2018 21.91 Kb 853
9354 High dose Elite Athletes.pdf admin 16 Feb, 2018 352.85 Kb 897