There is an increasing concern regarding vitamin D deficiency in athletes such as dancers who train indoors. As outlined in an update to MedGen on Aug. 24, vitamin D forms naturally in the body after exposure to sunlight, so those who lack exposure limit their vitamin D production making them more susceptible to serious bone diseases such as osteoporosis, rickets, or scoliosis. In a new study to be published in September’s J Sci Med Sport, researchers from the National Institute of Dance Medicine and Science, UK, compared the vitamin D status of UK professional dancers during periods of varying sunlight exposure, and assessed how these changes impacted the dancers’ risk of injury.
Vitamin D helps the body absorb calcium, which is critical for proper bone growth. Within the kidney, serum levels of 25-hydroxyvitamin D change into the active form of the vitamin that regulates the body’s calcium and phosphate levels. According to a U.S. Institute of Medicine committee, a serum 25-hydroxyvitamin D level of 20 nanograms per milliliter (ng/mL) is desirable for bone and overall health, while other sources such as Medline Plus recommend an even higher range of 30.0 to 74.0 (ng/mL) as desireable.
The UK researchers monitored 19 elite classical ballet dancers over a 6 month period, assessing their serum levels of 25-hydroxyvitamin D along with injury occurrence. Significant changes in serum levels were seen between the winter and summer test dates, with higher summer levels of 23.9ng/ml, decreasing to 14.9ng/ml in the winter. While a corresponding inverse rate of injury risk existed, with dancer soft tissue injuries lower in summer (13) compared to that in winter (24), the researchers noted that even the higher serum summer levels were at the lowest end of the normal range. This suggests that dancers, who primarily train indoors year round can be at an overall greater risk for Vitamin D deficiency than the athlete who is primarily inside only during the winter season.
An earlier Journal of Science and Medicine in Sport April 13 study found that oral supplementation of vitamin D3 to be beneficial to muscular performance and to decreased injury risk for classical elite ballet dancers. When 24 elite ballet dancers participated in the controlled 4-month oral supplementation of vitamin D3 (2000 IU per day), significant increases were noted: those in the intervention group showed greater increases in both isometric strength and vertical jump performance, compared to those in the control group. The intervention group also had a decreased rate of injury occurrence.
How much vitamin D the body can produce from sunlight depends on the time of day, location, skin color and the amount of skin exposed. According to the Vitamin D Council the skin needs to be exposed for around half the time it takes for it to turn pink and begin to burn. The National Institutes of Health (NIH) Office of Dietary Supplements recommends approximately 5–30 minutes of sun exposure between 10 AM and 3 PM twice weekly to the face, arms, legs, or back without sunscreen as usually sufficient to produce vitamin D synthesis. When sun exposure is limited, supplementation is advised, but recommended amounts can vary: for adults the Food and Nutrition Board advises 600-4,000 IU/day, while other organizations recommend up to 10,000 IU as appropriate.
While anyone with limited sun exposure needs to include good sources of dietary vitamin D or take a supplement to achieve recommended intake levels, the nature of the dancer’s training and lifestyle make it an even more critical need for adherence. Since vitamin D deficiency can also result from an unbalanced diet and poor food absorption, dancers who are prone to disordered eating habits resulting in low caloric and calcium intake are at an even increased risk to experience the effects from deficiency such as early bone loss, high incidence of stress fractures, and scoliosis, as well as osteopenia or osteoporosis.
Vitamin D Modification: MedGen 24 Aug, 2013 MedGen UID: 22670•Concept ID: C0042866•Pharmacologic Substance
Vitamin D status in professional ballet dancers: Winter vs. summer: published online 04 Feb. 04, JSAM .org., J Sci Med Sport, Volume 16, Issue 5 , Pages 388-391, September 2013 Wolman R, Wyon MA, Koutedakis Y, Nevill AM, Eastell R, Allen N. National Institute of Dance Medicine and Science, UK.
The influence of winter vitamin D supplementation on muscle function and injury occurrence in elite ballet dancers: A controlled study, Journal of Science and Medicine in Sport, online 23 April 2013 In Press, Corrected Proof, Matthew A. Wyon Yiannis Koutedakis, Roger Wolman, Alan M. Nevill