While it is well established that vitamin D is necessary for optimal bone health recent evidence suggests that vitamin D status may also affect sports performance. Indeed, vitamin D deficiency may increase the risk of autoimmune diseases and can also have a negative effect on human immunity, inflammation, and muscle function (in the elderly). Thus, it is likely that compromised vitamin D status can affect an athlete's overall health and ability to train (i.e., by affecting bone health, innate immunity, and exercise-related immunity and inflammation).
Although, more studies are needed, it seems that athletes’ vitamin D status is dependent on various factors, such as: total time of training outdoors daily, skin color and geographic location. Regarding location, new data show that serum 25-hydroxyvitamin D levels (a marker of vitamin D status) is low in middle east athletes and this could be due to low sun exposure during the hot months of years. It seems also that players in North Europe are at a higher risk of low vitamin D levels in the winter that other players.
Sports scientists should regularly assess vitamin D levels in athletes. Some recommendations to maintain normal vitamin D levels are:
- Regular sun exposure (5-30min, 2 times/week depending on location, skin color and individual characteristics), or
- Dietary supplementation with 1,000-2,000 IU vitamin D per day