Vitamin D is an essential nutrient that regulates some 1,000 processes in the body, and doctors have long known its importance to bone density and preventing the related illnesses like rickets and osteoporosis. Now researchers are beginning to study its role in athletic performance. While an extra dose of vitamin D might increase muscle strength and endurance, the science is far from settled. Still, many athletes are eyeing the vitamin for possible performance gains.
Given that the science is still young, is it worth hitting the drugstore? To find out, we reached out to some experts to understand what we know about the nutrient and what that means for athletes.
The Basics of Vitamin D
The main sources of vitamin D are sunshine and certain foods, including salmon, cod liver oil, and fortified cereal and dairy products. The USDA suggests an intake of 600 International Units per day, or 800 IU for adults over 70. You can easily meet that recommendation by spending 15 minutes outside on a sunny day.
In athletes, a vitamin D deficiency increases your risk of stress fractures, anemia, and a weakened immune system—all of which can hurt performance. In a study of 214 NFL players, scientists observed more muscle injuries in athletes with lower vitamin D levels. There’s no clear consensus about how widespread the deficiency is. In 2015 review, scientists found that about 56 percent of athletes had inadequate levels of the vitamin. Still, in a large-scale review, researchers at the National Academy of Medicine (then the U.S. Institute of Medicine) observed that, on average, Americans’ vitamin D levels appeared fine.
One cause of this discrepancy is that scientists don’t agree on the definition of “adequate” when it comes to vitamin D levels. The most common test for the nutrient measures a precursor version of its hormone form—the form of the vitamin that is actually used by the body. Sometimes this precursor doesn’t predict how much vitamin D exists in hormone form. Certain researchers, like those with the Endocrine Society, argue for higher concentration thresholds than than those of the National Academy of Medicine.
That said, some factors might increase your likelihood of a deficiency, such as living far away from the equator. During the Canadian winter, for example, it’s nearly impossible for your body to naturally produce vitamin D, says Dylan Dahlquist, a researcher and editor at Science Driven Nutrition. To prevent skin cancer, many people avoid unfiltered sun exposure entirely, says Graeme Close, a professor of sport and exercise sciences at Liverpool John Moores University. Though Close advises precautionary measures to avoid sunburns, ten to 15 minutes of UV exposure will help meet your daily vitamin D needs. Fair-skinned people can sustain sun-related skin damage in as little as five minutes, so vitamin D is no excuse to skimp on protection.
Skin tone is also a factor in how our bodies produce and use vitamin D. Higher-melanin skin blocks more UV rays, limiting vitamin D production. Some experts think this puts darker-skinned athletes at higher risk of a deficiency, but it’s still unclear what this means for bone health. “Some of the athletes with the strongest bones I have ever tested are darker skinned [and have] low vitamin D,” Close says. “It may be incorrect to have a blanket target concentration for all people.” So, while there’s a correlation between vitamin D and bone health and between dark skin and vitamin D absorption, the connection between dark skin and poor bone health is a leap that still isn’t backed by robust research.
Read more at: https://www.outsideonline.com/2339421/can-vitamin-d-boost-your-performance