Benefits Of Vitamin D

From Charles Poliquin


Take vitamin D to prevent injuries and increase strength. Research shows that your risk of vitamin D deficiency increases exponentially during the winter months. In athletes, this leads to a much greater risk of injury and compromised performance.


A new study reminds us of the benefit of maintaining vitamin D status year-round. Researchers followed 19 British professional female ballet dancers and found that ALL of the dancers had low vitamin D levels during the winter, and 85 percent were clinically deficient. Injury rates were higher during the winter, which researchers guess is due to low vitamin D since it is a pro-hormone that is required for optimal muscular performance.


During winter, the dancers vitamin D status was on average 14.9 ng/ml compared to 23.9 ng/ml in the summer. Below 20 ng/ml is considered “deficient,” whereas above 30 ng/ml is “normal.” Therefore, a level below 30 ng/ml is considered low, and the researchers were alarmed that 100 percent of the dancers had low D during the summer. The obvious solution is to take a vitamin D supplement year-round and to get blood levels tested during the winter so as to make sure adequacy is maintained.


In addition, bone health markers in the dancers were found to decrease significantly over the winter months when vitamin D level was lowest, providing evidence that lack of vitamin D increases bone loss in women. An interesting outcome of this study was that the women who were on oral contraceptives had higher vitamin D levels in both winter and summer, although their levels were still suboptimal.


This may indicate that the extra estrogen provided in the pill improves vitamin D metabolism, but it could also mean that women on the pill actually need more vitamin D to achieve a healthy status since it’s thought that the pill alters the proportion of bound to free vitamin D.


It should be noted that other studies into how medications affect vitamin D status show that the vast majority significantly lower vitamin D, especially asthma, heart, diabetes, and pain medications. A study of older adults on prescription medications found vitamin D levels that were between 4 and 7 ng/ml lower than those who were not taking medications.


Previous studies of athletes show a deficient vitamin D status increases injury risk: Large surveys of the Israeli and Finnish military have shown that the incidence of stress fractures was correlated with low vitamin D. A study of NFL football players showed a similar trend for injury rates, with injuries increasing as vitamin D levels decreased.


Take away a commitment to getting your vitamin D level checked and supplement accordingly. Know that the following things significantly increase your risk of being deficient:

• Having dark skin. People with dark pigmentation do not make vitamin D to the same degree as those with light skin.

• Wearing sunscreen and sunglasses in the sun can impede the body’s ability to make vitamin D.

• Being older—over 55 years old.

• Taking one or more prescription medication. Taking an NSAID like Ibuprofen or Tylenol may also lead to lower vitamin D.

• If you are overweight, your are much more likely to be vitamin D deficient.


Wolman, R., et al. Vitamin D Status in Professional Ballet Dancers: Winter Versus Summer. Journal of Science and Medicine in Sport. 2012. Published Ahead of Print.



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