"Vitamin D is an often overlooked element 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. Vitamin D once was thought to be primarily involved in bone development. But a growing body of research suggests that it’s vital in multiple different bodily functions, including allowing body cells to utilize calcium (which is essential for cell metabolism), muscle fibers to develop and grow normally, and the immune system to function properly. “Almost every cell in the body has receptors” for Vitamin D, Anderson says. “It can up-regulate and down-regulate hundreds, maybe even thousands of genes,” Larson-Meyer says. “We’re only at the start of understanding how important it is.”"
You can get Vitamin D from the sunshine, but many people these days avoid the sun or apply sunscreen. Getting enough Vitamin D from our diet and in the proper amounts is not that easy.
Meanwhile, dietary sources of Vitamin D are meager. Cod-liver oil provides a whopping dose. But a glass of fortified milk provides a fraction of what scientists now think we need per day. (A major study published online in the journal Pediatrics last month concluded that more than 60 percent of American children, or almost 51 million kids, have “insufficient” levels of Vitamin D and another 9 percent, or 7.6 million children, are clinically “deficient,” a serious condition.Although the article stresses that few studies have looked closely at the issue of Vitamin D and athletic performance, some of what researches have found is interesting. There are even hints that it may help you jump higher (one study found that adolescent athletes who had lower levels of Vitamin D tended not to jump as high as those with higher levels) and run faster (Russian and German sprinters improved their sprint times by dosing with Vitamin D and using sun lamps). Running faster and jumping higher was something that I thought only Keds shoes could do.
The author writes:
A number of recent studies also have shown that, among athletes who train outside year-round, maximal oxygen intake tends to be highest in late summer, Johnson says. The athletes, in other words, are fittest in August, when ultraviolet radiation from the sun is near its zenith. They often then experience an abrupt drop in maximal oxygen intake, beginning as early as September, even thought they continue to train just as hard. This decline coincides with the autumnal lengthening of the angle of sunlight. Less ultraviolet radiation reaches the earth and, apparently, sports performance suffers.I am one of those runners that feel fittest during the summer and have a decline in the winter months. Whether that is true because of a lack of Vitamin D or the fact that I don't like the cold., I am not sure. The author claims the blood test is simple to do if you want to look for deficiences and taking a supplement is easy. I really don't take any vitamins or supplements, but I would like to know more about this Vitamin D research. It is cheap if you can't get out in the sun. A year's supply
costs less than $15.00.
I do recall reading a article last spring where Deena Kastor blamed her broken foot at mile 3 of the Beijing Olympic Marathon on a lack of Vitamin D. Due to her skin cancer, she lathers up with sunscreen and wears hats when outdoors. With a Vitamin D deficiency, her bones were weakened, because they could not absorb calcium properly. Her foot broke at the most inopportune time. Here is an interview where Deena explains what happened and what she learned.
Peak Athletic Performance and Vitamin D
Vitamin D Increases Athletic Performance
Mike T. Nelsons's blog Vitamin D and Athletic Performance
The Vitamin D Cure