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fatigue, frequent respiratory infections, muscle and bone pain, and delayed regeneration can be caused by a lack of vitamin D? 

This can have serious consequences, especially for endurance athletes, as low vitamin D levels not only affect performance, but also increase the risk of injury.

According to a 2023 study, 47.9% of the world's population suffers from vitamin D deficiency, with men more often affected than women. Older people and athletes, who often spend time indoors or train early in the morning or late in the evening, are also particularly at risk.

Vitamin D is mainly absorbed by sunlight and, to a lesser extent, by food. Those living in northern latitudes (i.e. in central or northern Europe) have an increased risk of a deficiency, especially in winter, when solar radiation is limited or the sun's height is simply not enough to provide enough UVB rays for vitamin D production. In addition, intensive training can strain the immune system, which increases the susceptibility to infections. This is where vitamin D plays an important role: it not only supports bone health, but also muscle function and the immune system – essential for good performance and rapid recovery.

Exposure to sunlight is crucial

It is best to spend as much time as possible outdoors – ideally during the midday hours, when the sun's radiation is strongest. Especially for endurance athletes, training outdoors is ideal for supporting vitamin D production at the same time. The good news The body is able to regulate excess vitamin D itself, so overdose due to sun exposure is not possible.

If your daily routine does not allow you to absorb enough sun, you should pay attention to a vitamin D-rich diet. Particularly fatty marine fish such as salmon, mackerel and herring are excellent natural sources. Fish oil capsules offer a practical alternative for a targeted supply. Enriched foods such as dairy products or eggs can also help to improve vitamin D levels.

Given the negative health effects of inadequate vitamin D levels, it is useful to prevent this problem. If you suspect a deficiency, have a blood test done that gives you a clear answer.

What can we learn from this?

• Vitamin D is essential for endurance athletes. However, sufficient absorption via sunlight is a problem in winter, because the sun's height is often too low to provide enough UVB rays for vitamin D production.
• If you want to absorb vitamin D via the skin, you must make sure that you do this between 10 am and 3 pm, and that you do not overly cover your skin with clothing or are protected by sunscreen. Time spent outdoors without sun protection should be in moderation, however, to avoid skin damage.
• At higher altitudes, UV radiation is more intense – one more reason to head to the mountains in winter. In addition, reflective surfaces such as snow enhance sunlight and can support vitamin D production.
• In the absence of sun exposure, it is worth travelling south to sunnier climes.
• In addition to the sun, a targeted diet with fatty fish, eggs, mushrooms or enriched foods can help.
• Fish oil capsules are an effective alternative if sufficient intake via food is not possible.

An optimal vitamin D supply can make all the difference – for better performance, faster recovery and fewer infections. So get out into the sun and stay healthy!