In a study exploring the link between vitamin D and levels of physical fitness, researchers discovered that people who had a higher capacity for exercise also had higher levels of the nutrient in their blood. This suggests that having an ample amount of vitamin D in your diet can help boost your exercise stamina.
For the study, researchers looked at survey responses from nearly 2,000 adults ages 20-64, both men and women. All of them suffered from a range of different health issues including diabetes and high blood pressure. Regardless of these factors, those who performed the best physically also had higher levels of vitamin D, across the board.
Dr. Amr Marawan, lead study author and an assistant professor of internal medicine at Virginia Commonwealth University, said:
“The relationship between higher vitamin D levels and better exercise capacity holds in men and women, across the young and middle-age groups, across ethnicities, regardless of body mass index or smoking status, and whether or not participants have hypertension or diabetes.”
However, the researchers warn that consuming too much vitamin D can have negative ramifications for your health. But it’s quite difficult to overdo it with vitamin D, as it would require taking in approximately 60,000 international units (IU) of vitamin D daily to induce toxicity, while normal supplements usually provide 1,000-5,000 IUs.
Going overboard on the vitamin can also lead to hypercalcemia – abnormally high levels of calcium in the blood. The condition can lead to cardiovascular problems or softened tissue as well as nausea, vomiting, and weakness.
“It is not the case that the more vitamin D the better. Toxicity is caused by megadoses of supplements rather than diet or sun exposure, so caution is needed when taking tablets.”
But aside from potentially overdoing it, it’s important to maintain a healthy level of the vitamin. Also, it is best to get your vitamin D from diet and sunshine, rather than from supplements.
Of course, vitamin D deficiency comes with its own problems. Research suggests that women who don’t get enough vitamin D during pregnancy are more likely to have a child with attention-deficit hyperactivity disorder (ADHD). A lack of the vitamin during pregnancy can also affect an unborn child’s future social development and social skills. For pregnant women, taking vitamin D supplements is usually recommended and believed to prevent these problems.
The study also found that people with higher vitamin D levels also tended to have better cardiorespiratory fitness. 
Cardiorespiratory fitness (CRF) is a measure of a person’s aerobic fitness level. In the study, the higher a participant’s vitamin D level was, the greater their cardiorespiratory fitness was, the researchers found.
However, the study only found an association rather than a cause-and-effect relationship between vitamin D and cardiorespiratory fitness.
“We don’t know if higher vitamin D levels improved CRF or [if] CRF improved vitamin D levels.”
The study is published in the European Journal of Preventative Cardiology.
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