|(c) Koji Aoki|
Significant differences were found in levels of serum 25-hydroxyvitamin D, PTH and blood serum bone turnover markers between summer and winter months. Although levels of 25-hyrdoxyvitaminD were higher in summer months, only 3 of the 19 dancers achieved "sufficient" levels during the summer period, with the rest being considered either insufficient or deficient in vitamin D. All dancers' vitamin D levels were found to be insufficient or deficient in winter months.
A significant decrease in injury instances in summer months (p<0.05) was observed, suggesting low vitamin D status increases likelihood of injury occurence. Further to this, the study found that use of oral contraceptives appeared to increase serum 25-hydroxyvitamin D levels and had a positive effect on bone metabolism.
The study reaffirms the position that athletes who train indoors - dancers, swimmers, gymnasts, martial artists - are at risk of vitamin D deficiency. The study provides further evidence that vitamin D insufficiency and deficiency are considerable concerns for professional dancers and athletes who train indoors, increasing likelihood of injury occurence and having a detrimental effect on bone metabolism.
Source: Wolman R, Wyon MA, Koutedakis Y, Nevill AM, Eastell R, Allen N. (2013) Vitamin D status in professional ballet dancers: Winter vs. summer. Journal of Science and Medicine in Sport.