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What is vitamin D?

April 15, 2025

Vitamin D plays an important role in your body and well-being. But many people don't know exactly what it does or how to get enough of it.

Vitamin D from the sun

Why is vitamin D important?

Vitamin D is a fat-soluble vitamin that the body uses to absorb calcium and phosphate - both necessary for healthy bones and teeth.

Too little vitamin D can lead to fatigue, weakened bones and, in the worst case scenario, diseases such as rickets in children or osteoporosis in adults. That's why it's important to pay attention to your levels - especially during the winter months when the sun is scarce.

How do you get vitamin D?

The primary source of vitamin D is sunlight. When your skin is exposed to the sun's UVB rays, your body produces vitamin D itself.

You can also get vitamin D through diet, especially from fatty fish like salmon and mackerel, egg yolks and fortified foods like milk and plant milk. In Denmark, it is recommended that certain groups take supplements - especially during the winter months.

Who is at risk of vitamin D deficiency?

Vitamin D deficiency is particularly prevalent among the elderly, people with dark skin, pregnant women, and those who spend a lot of time indoors or cover their bodies with clothing.

Be aware if:

  • You feel abnormally tired.
  • You have muscle weakness or sore joints.
  • You are often sick with infections.

These symptoms can be signs of deficiency and should be investigated further.

Symptoms of vitamin D deficiency

Vitamin D deficiency often develops slowly and can be difficult to detect. Fatigue, depression and body aches are some of the typical signs.

In children, it can cause growth problems and bone deformities, while in adults it can lead to osteoporosis or muscle weakness. It is therefore important to take the symptoms seriously.

Can you get too much vitamin D?

Yes, but it's rare. Overdosing typically only occurs with very high supplement intake and can lead to high blood calcium levels, kidney problems and nausea.

Therefore, it is always recommended to take supplements in consultation with a doctor if you are in doubt about your needs.

When should you get your vitamin D tested?

If you have symptoms of deficiency, belong to a risk group or have a chronic disease that may affect absorption, you should consider having your vitamin D levels measured.

At Doctors Denmark, we can take a blood test and give you answers quickly so you know if you need supplements.

Vitamin D and the immune system

Several studies show that vitamin D plays a role in the immune system and can help prevent infections and viral diseases - including flu and respiratory infections.

While not a guarantee against disease, it is an important part of the body's defense mechanisms.

Get guidance from your private doctor

At Doctors Denmark, you can get individual advice and help to find out if you need vitamin D supplementation.

We offer fast appointments and easy access to blood tests so you can know for sure - on your terms. And we guide you confidently if you need treatment or dietary advice.