Br J Sports Med. 2013 Feb 14. [Epub ahead of print]
The effects of vitamin D3 supplementation on serum total 25[OH]D concentration and physical performance: a randomised dose-response study.
Close GL, Leckey J, Patterson M, Bradley W, Owens DJ, Fraser WD, Morton JP.
Source
Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK.
Abstract
BACKGROUND:
Vitamin D deficiency is common in the general public and athletic populations and may impair skeletal muscle function. We therefore assessed the effects of vitamin D(3) supplementation on serum 25[OH]D concentrations and physical performance.
METHODS:
30 club-level athletes were block randomised (using baseline 25[OH]D concentrations) into one of three groups receiving either a placebo (PLB), 20 000 or 40 000 IU/week oral vitamin D(3) for 12 weeks. Serum 25[OH]D and muscle function (1-RM bench press and leg press and vertical jump height) were measured presupplementation, 6 and 12 weeks postsupplementation. Vitamin D deficiency was defined in accordance with the US Institute of Medicine guideline (<50 nmol/l).
RESULTS:
57% of the subject population were vitamin D deficient at baseline (mean?SD value 51?24 nmol/l). Following 6 and 12 weeks supplementation with 20 000 IU (79?14 and 85?10 nmol/l, respectively) or 40 000 IU vitamin D(3) (98?14 and 91?24 nmol/l, respectively), serum vitamin D concentrations increased in all participants, with every individual achieving concentrations greater than 50 nmol/l. In contrast, vitamin D concentration in the PLB group decreased at 6 and 12 weeks (37?18 and 41?22 nmol/l, respectively). Increasing serum 25[OH]D had no significant effect on any physical performance parameter (p>0.05).
CONCLUSIONS:
Both 20 000 and 40 000 IU vitamin D(3) supplementation over a 6-week period elevates serum 25[OH]D concentrations above 50 nmol/l, but neither dose given for 12 weeks improved our chosen measures of physical performance.