Previous Page
SPORTS MEDICINE VITAMIN D DEFICIENCY
supplementation strategies available, both in the literature and in practice. We have found that intramuscular vitamin D2
in doses of 300,000 IU
brings about an adequate elevation in 25(OH)D levels.
Access to intramuscular injections
of vitamin D, however, varies from country to country. Advice regarding sunlight exposure
is also variable. It needs to be regionally specific and tailored to the individual because of differences in skin darkness, latitude, times of day and seasons, so different periods of exposure may be required for the same net benefit. While aiming to promote exposure
Figure 7: Internal and external influences on vitamin D production
to sunlight, the benefits of ultraviolet B exposure on vitamin D levels must always be balanced against the risk of skin cancer, which is a major issue in some parts of the world. Our centre applies the following broad recommendations (Table 1). Some foods provide small amounts
of vitamin D. These include oily fish, egg yolk, fortified cereals and some yeast products. In some countries, milk,
EXTRINSIC FACTORS n Skin coverings (eg. clothes) n Sunscreen application n Lack/avoidance of sunlight n Low sunlight hours n High latitude
Adults* Children*
TABLE 1: RECOMMENDED TIMES FOR EXPOSING FACE, HANDS, ARMS AND LEGS TO SUNLIGHT 2–3 TIMES PER WEEK
Pigmented skin 20–30 minutes 10–15 minutes
*Avoid mid-day exposure.
butter, margarine and other foods are fortified to provide additional sources. It is unlikely that dietary sources will ever be adequate to maintain levels of 30 ng/ml.
SUMMARY
Vitamin D is a poorly named endogenous steroid hormone whose role is only now beginning to be fully understood. It doesn’t just have a role in calcium metabolism and bone health – it is now implicated in long-term health as well as physical performance. Deficiency of the vitamin is common nowadays, even in groups previously not considered at risk. As a result, it should now form part of any routine assessment in elite athletes, in people at risk of low ultraviolet light exposure, or any patients presenting with atypical aches and pains. Identification and correction of levels should be expedited and form part of the overall management of the athlete.
References INTRINSIC FACTORS
n Dark skin (lowered absorbtion of ultraviolet rays
n Renal/liver disease (reduced ability to convert vitamin D)
n Reduced intestinal absorbtion
n Vitamin D resistance
1. Holick M. Vitamin D deficiency. New England Journal of Medicine 2007;357(3):266–281 2. Holick M. High prevalence of vitamin D inadequacy and implications for health. Mayo Clinical Proceedings 2006;81(3):353–373 3. Hoberman J. Mortal engines: the science of performance and the dehumanization of sport, 1st edn. 1992. The Free Press. ISBN 9781930665378 4. Cannell J, Hollis B, Sorenson M, et al. Athletic performance and vitamin D. Medicine and Science in Sports and Exercise 2009;41(5):1102–1110 5. Sato Y, Iwamoto J, Kanoko R, et al. Low-dose vitamin D prevents muscular atrophy and reduces falls and hip fractures in women after stroke: A randomized controlled trial. Cerebrovascular Diseases
2005;20:187–192 6. Iannuzzi-Sucich M, Prestwook K, Kenny A. Prevalence of sarcopenia and predictors of skeletal muscle mass in healthy, older men and women. Journal of Gerontology 2002;57A(12):M772–M777 7. Bischoff-Ferrari H, Dietrich T, Orav E, et al. Higher 25-hydroxyvitamin D concentrations are associated with better lower-extremity function in both active and inactive persons aged 60 years. American Journal of Clinical Nutrition 2004;80:752–758 8. Bischoff H, Stahelin H, Urscheler N, et al. Muscle strength in the elderly: Its relation to vitamin D metabolites. Archives of Physical Medicine and Rehabilitation 1999;80:54–58
9. Latham N, Anderson C, Reid I. Effects of vitamin D supplementation on strength, physical performance, and falls in older persons: A systematic review. Journal of the American Geriatric Society 2003;51:1219–1226 10. Latham N, Anderson C, Lee A, et al. A randomized, controlled trial of quadriceps resistance exercise and vitamin D in frail older people: The Frailty Interventions Trial in Elderly Subjects (FITNESS). Journal of the American Geriatric Society 2003;51:291– 299 11. Bischoff-Ferrari H, Borchers M, Durmuller U, et al. Vitamin D receptor expression in human muscle tissue decreases with age. Journal of Bone and Mineral Research 2004;19(2):265–269 12. El-Hajj G, Nabulsi M, Tamim H, et al. Effect of vitamin D replacement on musculoskeletal parameters in school children: A randomized controlled trial. The Journal of Clinical Endocrinology and Metabolism 2006;91(2):405–412 13. Ward K, Das G, Berry J, et al. Vitamin D status and muscle function in post- menarchal adolescent girls. Journal of Clinical Endocrinology and Metabolism 2009;94:559–563 14. Bischoff H, Borchers M, Gudat F, et al. In situ detection of 1,25-dihydroxyvitamin D3 receptor in human skeletal muscle tissue. The Histochemical Journal 2001;33(1):19– 24
AND INCREASING ATTENTION IS BEING PAID TO THEIR VITAMIN D STATUS
ATHLETES ARE NOT IMMUNE TO DEFICIENCY OF VITAMIN D
Non-pigmented skin 10–15 minutes 5–10 minutes
15