There’s another reason to make sure you’re getting enough of the sunshine vitamin: High levels of vitamin D in the blood are now linked with better fitness, according to research from the Virginia Commonwealth University School of Medicine. In the study, published in the European Journal of Preventive Cardiology, 20- to 49-year-olds with better vitamin D status also tended to have greater cardiorespiratory fitness, a measure of aerobic fitness often determined by measuring maximal oxygen consumption (VO2max) during exertion.
Muscle cells have receptors for vitamin D; that might explain why this nutrient can influence athletic performance. Admittedly, the study showed only an association between vitamin D and cardiorespiratory fitness and did not prove that high vitamin D levels increase people’s ability to run harder for longer. Even so, it seems like a good idea for fitness-minded folks to make sure they get enough vitamin D via safe amounts of sun exposure, dietary sources like fatty fish and fortified dairy, and supplementation if a physician or dietitian deems it necessary.