Vitamin D Role in Athletes Body

Vitamin D Role In Athletes Body
Can Vitamin D Improve Your Athletic Performance? Are Athletes typically deficient in Vitamin D?

Till not long ago, it was thought that the prime function of the "sunshine vitamin" or Vitamin D was to maintain good bone health. Now its importance in preventing a large range of age related diseases including many types of cancer, hypertension, diabetes and heart disease has also been recognized. It is a well known fact that Vitamin D is synthesized by the body when the skin is exposed to the ultraviolet B rays of the sun. Almost 90% of the daily needs can be met this way.

Recent research has been focusing on the crucial link between Vitamin D status and level of athletic performance. Vitamin D is a nutrient that is often overlooked in athletic achievement, a "sleeper nutrient," says John Anderson, a professor emeritus of nutrition at the University of North Carolina and one of the authors of a review article published online in May about Vitamin D and athletic performance.

• Scientists at The Australian Institute of Sport checked the Vitamin D status of 18 female gymnasts. While 15 had levels that were below the recommended guidelines for optimal bone health, 6 were categorized as deficient. Poor diet and inadequate sun exposure were probably responsible.
• In yet another study it was found that many members of a group of distance runners suffered from poor Vitamin D status. Even amongst runners who trained outdoors in the sunny area of Baton Rouge, forty percent had insufficient Vitamin D. They most likely ran early in the morning or late in the day, to reduce their risk of getting sun burnt, but they also reduced their exposure to sunlight.
• Studies conducted decades ago in Russia and Germany, hinted that the Eastern Bloc nations may have depended in part on sunlamps and Vitamin D to produce muscular and world number one athletes. Comparisons were made between performance of athletes who received radiation and those who did not. Results were favorable for the first group. Although the number of studies was few, they have been suggestive of the link between Vitamin D and performance.
• More recently, a comparison of the vertical jumping ability of a small group of adolescent athletes revealed that those with a lower status of Vitamin D tended not to jump very high. This again suggests that a low level of vitamin D may impair muscle power. Low levels might also contribute to sports injuries.
• Studies conducted on performance of outdoor performing athletes at different times of the year, showed that the maximal oxygen intake is highest in late summer. Athletes are fittest in August, when the sun's ultraviolet radiation rays are at its maximum. With no other factor changing, their maximal oxygen intake begins to drop from September. This is the time when the autumnal lengthening of the angle of sunlight leads to a decrease in UV rays which reach the earth. This also causes a drop in sports performance.

What is the role of Vitamin D in athletic performance?
Research has suggested that the vitamin allows cells to use calcium and muscle fibers to develop and grow normally. It also helps the immune system to function efficiently. "Almost every cell in the body has receptors" for Vitamin D, says Anderson. "It can up-regulate and down-regulate hundreds, maybe even thousands of genes".

Causes of Low Vitamin D levels in Athletes / Low vitamin D levels in Children / Low vitamin D levels in active adults
Results of a study published online in the journal Pediatrics last month revealed that more than 60 percent American children, have "insufficient" levels of Vitamin D and another 9 percent are clinically "deficient." Cases of rickets have been rising recently. Similar studies across the world have revealed similar results.

Vitamin D deficiency is now recognized as a pandemic global problem. The primary cause is inadequate exposure to sun. This could be because:

• People, especially children now spend more time in indoor activities
• Fear of overexposure that could result in skin damage or skin cancer.
• Melanin (skin pigment) acts as a light filter in the skin and reduces the amount of Vitamin D synthesized. Darker skinned people need longer exposure periods.
• Use of sun screens decreases the body's ability to synthesize Vitamin D. In combination with high melanin sunscreeners can reduce the synthesis by 99%.
• The practice of "purdah" increases the risk of deficiency in the sunniest areas of the world.
• Inadequate UV rays available to people living in "northern climates"
• Very few foods contain adequate amounts of natural vitamin D e.g. fish oils are extremely rich sources but they cannot be consumed in large quantities. Fatty fish are also rich sources though not an option for vegetarians.
• Fortification of foods is either not a common practice in some countries or is inadequate to take care of the daily needs.

How much Vitamin D do we need? What are the recommended daily allowances for Vitamin D?
The current United States RDAs for Vitamin D are

1. 400 IU for adults aged 51 to 70
2. 600 IU for people over 70.
3. 200 IU for all persons younger than 51

How to naturally boost Vitamin D levels in the body.
Simple tips will help increase vitamin D levels -

1. A combination of moderate exposure to sun
2. Consumption of fortified foods
3. Only if needed supplementation (only after consulting a physician) can help maintain optimal levels.
4. Non vegetarians should include more fatty fish in their diets.

Researchers are of the opinion that we are only beginning to understand the importance of this vitamin and the RDA may need to be raised in the near future as these quantities may prove to be inadequate.

Till then, we could keep track of our current vitamin D status. A simple test of 25(OH) D in the blood should show a reading of at least 50 nanograms per millilitre.

By Poonam Vaswani,
Sr. Dietitian,
NutritionVista.com

References

• American Journal of Clinical Nutrition, Vol. 87, No. 4, 1080S-1086S, April 2008).
• American Journal of Clinical Nutrition, Vol. 83, No. 6, 1411-1419, June 2006

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