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Athletes who train indoors risk lacking vitamin D

 Athletes who train indoors risk lacking vitamin DA lot of sports and fitness disciplines are indoor activities. According to a new American study, this increases the risk of becoming vitamin D-deficient. Not only can a vitamin D deficiency hamper your performance, it can also increase your risk of acute infections, chronic inflammation, osteoporosis, cancer, and a number of other health problems. To make matters worse, people living at northern latitudes can only synthesize vitamin D in their skin during the summer period where the sun sits high in the sky, and the body’s vitamin D stores are limited during the winter period.

Vitamin D is primarily known for its role in bone health, muscle health and calcium uptake, but most cells in the body have vitamin D receptors that control the activation of different genes and a variety of biochemical processes in the body. Even if a vitamin D deficiency is not necessarily something that you register it may have sudden or long-term consequences because immune cells, bone cells, muscle cells, pancreas cells, and cells in other organs fail to function properly.

Vitamin D deficiency is common among athletes – especially those of color

The study is carried out by scientists from George Mason University in Virginia and Mayo Clinic Health System Sports Medicine Research in Wisconsin and includes 20 male and female elite basketball players from the George Mason Patriots. All study participants had their blood levels of vitamin D measured in the course of the 2018-2019 season. At baseline, the scientists looked at the players’ vitamin D status and assigned them to either high-dosed or low-dosed vitamin D supplementation, or no supplementation at all. The researchers did this in order to find out what dose was required to optimize vitamin D levels in the blood. Also, they looked at skin color, body structure, sun exposure levels, and eating habits.
The team coaches made sure that all the players took their supplements. In the course of the season, the scientists regularly measured the players’ blood levels of vitamin D.
At baseline, 13 (65%) of the 20 basketball players had low vitamin D levels in their blood. This supports a new, systematic meta-analysis showing that 56 percent of 2,000 athletes from nine different countries, including the United States, had insufficient vitamin D levels in their blood.
It was primarily dark-skinned athletes that lacked vitamin D at baseline. This has a natural cause, as dark skin does not synthesize vitamin D as easily as lighter skin does. On the other hand, dark skin is better protected against the UV-rays from the sun.
Nicole Sekel from George Mason University who headed the study is not only interested in bone health but also wants to study whether diet can contribute to improved athletic performance. Although this was only a small pilot study the results offer more proof that vitamin D deficiencies are common among top-notch basketball players. The researchers behind the new study say that more studies are needed from different parts of the US to reveal all the different risk factors that are seen in vitamin D-deficient athletes.

Vitamin D supplements have positive effects on sports performance and heart function

According to an earlier study that was presented at an endocrinology conference in Edinburgh, vitamin D supplements can improve athletic performance and lower the risk of cardiovascular disease. Vitamin D can block cortisol, a stress hormone that makes your blood pressure go up.
Doctor Emad Al-Dujaili, who headed this study, says that lack of vitamin D is an insidious problem that is linked to other health problems such as insulin resistance, diabetes, rheumatoid arthritis, and an increased risk of several cancer forms. The two studies described above therefore deliver new evidence of how important it is to have adequate vitamin D levels in your blood at all times.

It is possible to cover your need for vitamin D in the summer period by spending enough time in the sun. In the winter, however, a high-dosed vitamin D supplement is recommendable because studies show that many people are vitamin D-deficient during the winter period.


Nicole M. Sekel et al. The Effects of Cholecalciferol Supplementation on Vitamin D Status Among a Diverse Population of Collegiate Basketball Athletes: A Quasi-Experimental Trial. Nutrients 2020

George Mason University. Athletes who play indoor sports at risk of vitamin D deficiency. ScienceDaily. March 9, 2020

Science News. Vitamin D pill a day may improve exercise performance and lower risk of heart disease. ScienceDaily 2016

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