Vitamin D levels: the most important questions and answers

Vitamin D-Spiegel: Die wichtigsten Fragen und Antworten

Our body is a highly complex machine. In order for this to function properly, it needs many different minerals, nutrients and vitamins. Vitamins A, C and E are usually emphasized. But the vitamin D level is often overlooked or not taken seriously.

Hardly anyone knows why vitamin D is so important. Nor how this value is measured and how we can compensate for a deficiency. This article answers all your questions about vitamin D levels and shows you why you should also enjoy sunbathing in winter.

the essentials in brief

  • Vitamin D is important for calcium regulation in the body. It therefore has a major influence on bone metabolism and our muscles.
  • Vitamin D is mainly obtained from the sun and diet. That's why you should enjoy sunbathing for about 30 minutes every day and eat a lot of fish.
  • In our latitudes, the majority of people suffer from vitamin D deficiency. It is therefore all the more important to test the vitamin D level so that a possible treatment can be made.

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Vitamin D levels: What you should know

Many already know that vitamin D can be obtained from exposure to the sun on the skin. But hardly anyone knows why vitamin D is so important, how it can be tested and what needs to be considered.

What is vitamin D?

Vitamin D is a group of fat-soluble vitamins (secosteroids). Together with calcium, it plays an important role in bone metabolism and therefore bone health. (10) Vitamin D has the following influences on the body:

  • ensures that the calcium level remains in the normal range
  • increases the absorption of calcium in the bones
  • increases calcium absorption in the blood
  • reduces calcium excretion via the kidneys
  • increases the formation and development of bone cells

As you can see, vitamin D is very important for calcium regulation in the body and therefore also for the bones.

In addition, vitamin D has a positive effect on the muscles. A balanced vitamin D level promotes the increase in muscle mass and gives you security in movement. You just feel more stable on your feet. (9)

What does the vitamin D level say?

The vitamin D level is determined using a blood test. This level provides information about the state of equilibrium between intake and consumption of vitamin D.

Vitamin D is stored in adipose tissue and muscles. As soon as the stores there are full, vitamin D is released into the bloodstream.

This means that the higher the vitamin D level, the better the body stores in the muscles and fat tissue. The level thus allows an assessment of the vitamin D supply in the body. (9)

What can I derive from the vitamin D level?

A blood test is usually carried out to measure the vitamin D level. For this purpose, the 25-OH-D serum in the blood is analyzed. (9)

Nowadays, the vitamin D level in the blood is given in different units. These often cause confusion, which is why you have to look carefully here.

The level is given in nanograms per milliliter (ng/ml), micrograms per liter (µg/l) or in nanomoles per liter nmol/l. 1 ng/ml corresponds to 2.5 nmol/l. As you can see, the different units also have different significance.

The laboratory findings of the blood test indicate whether the vitamin D supply status must be described as sufficient (adequate), insufficient (suboptimal) or deficient.

Which vitamin D level is normal or optimal?

Most laboratories classify levels below 20 ng/mL as mild vitamin D deficiency and levels below 12 ng/mL as severe deficiency. But actually the value should be much higher. (2)

Your vitamin D level should normally be at least 30 ng/ml. If not even 40 ng/ml. The upper limit is around 80 ng/ml. (1,2)

However, please note that people older than 60 years should have a higher mirror. Because their bones are already more brittle, which is why they need more vitamin D. (3.11)

Value mg/ml value nmol/L interpretation
under 20 under 50 Vitamin D deficiency
20 – 35 50-80 undersupply
35 – 60 80-150 normal value
60 – 90 150-225 Increased value
90-150 225-374 oversupply
over 150 over 374 Vitamin D poisoning

When should I measure vitamin D levels?

Basically, you don't need to test your vitamin D levels as long as you feel healthy. However, we get very little sun in our latitudes. We therefore suffer from vitamin D deficiency, especially in the winter months. Therefore, you should take suitable drops or other dietary supplements. (7)

Vitamin D oil bottle and mask

The optimal vitamin D level is above 40 ng/ml. In addition to sunbathing and nutrition, dietary supplements and preparations can also increase vitamin D levels. (Image source: / Dimitri Karastelev)

The measurement of the vitamin D level is mainly done by the doctor. This can determine the value via a blood test.

But the doctor rarely offers such a test himself. Most of the time you have to ask for it yourself.

In addition, the health insurance company rarely pays for the test. So keep in mind that you have to pay about 40 euros for the test at the doctor.

There are also home test kits. You can either order these online or buy them in any pharmacy. However, the costs here are also around 30 euros.

For the self-test, put a drop of blood on a card. You then send this to a laboratory, which evaluates the test. You will receive your results by post or email within a few days.

How does vitamin D deficiency become noticeable?

Since vitamin D is very important for calcium regulation and thus for the bones, a deficiency should be taken seriously. If you have a vitamin D deficiency, your bones are weaker and break more easily. (9.10)

Less calcium is built into the bones, which has a negative impact on their mass. As a result, the bones age and are less resilient. Thus, vitamin D deficiency not only reduces bone density, but also its quality. (9.10)

If your bones feel like they hurt or fractures heal very slowly, it may be due to a vitamin D deficiency. Other symptoms of vitamin D deficiency are depression and mood swings. (3)

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  • Get an automatic 21% discount when you buy now 💸*

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*The discount is automatically applied to the product

What diseases are there with regard to vitamin D levels?

The vitamin D level has an influence on the calcium metabolism. Thus, it also has a great influence on the bones. Vitamin D deficiency can lead to sprains and fractures more easily. Because a long-lasting vitamin D deficiency means that the bones are less supplied with the calcium they need. This makes them porous. (10)

Since children still have a different bone structure, vitamin D deficiency is rarely as harmful to health as it is in adults.

Diseases associated with persistent or severe vitamin D deficiency are often osteomalacia. This means bone softening with skeletal deformation. It can also lead to osteoporosis (bone loss) in people over the age of 60. (3,8,9)

Vitamin D deficiency or excess can also be symptoms of other diseases. Therefore, a test at the doctor's is never wrong.

Who are risk groups of vitamin D deficiency?

The majority of Germans, Austrians and Swiss suffer from vitamin D deficiency. But some are more at risk from low vitamin D levels than others.

  • Dark-skinned people need to spend more time in the sun to store the vitamin D they need. The reason for this is the higher melanin content of their skin, which shields UV-B radiation more effectively.
  • The chronically ill or those in need of care rarely spend time outdoors. Therefore, they also have fewer opportunities to obtain vitamin D from the sun. In addition, their immune system is already weakened from the ground up.
  • People over the age of 60 are considered at risk. This is because over time, the skin's ability to produce vitamin D decreases.
  • smoker

3 ways you can increase your vitamin D levels?

Since we mainly absorb vitamin D from food and the sun, a large proportion of the population suffers from vitamin D deficiency. Because especially in the autumn and winter months we can only soak up very little sun. (7)

Older people in particular should actively work on a vitamin D supply. Because with increasing age, the skin not only becomes slacker. It can also only process less vitamin. Since people over the age of 60 are more prone to falls and fractures, testing of vitamin D levels is advisable. (11)

Vitamin D tablets

You can get light dietary supplements without a prescription in any pharmacy. Stronger remedies require a prescription. (Image source: / Kayla Maurais)


One of the most important suppliers of vitamin D is the sun or the skin. The body obtains between 80 and 90 percent of the required vitamin D under the influence of sunlight.

When exposed to sunlight, the skin produces cholecalciferol, which is converted in the liver to 25-OH vitamin D3 (calcidiol).

Doctors recommend exposing the limbs to sunlight for at least 30 minutes a day. However, this always depends on the skin type and place of residence (e.g. Africa or Germany). (5.6)


Vitamin D can also be ingested through food. However, only small amounts of around 10 to 20 percent are possible here.

In addition to oily fish (herring and tuna), eggs and avocados, champions in particular are good sources of vitamin D. (3)

dietary supplements

After clarifying your vitamin D level with your family doctor, you can also take suitable dietary supplements or preparations.

It is recommended to consume 1,000 IU (International Unit) of vitamin D per day. This corresponds to 25 micrograms.

In addition to tablets, this can also be taken in the form of drops. These preparations are particularly suitable for a slight vitamin D deficiency. However, if you suffer from a serious deficiency, we recommend that you consult a doctor. They can then prescribe you a higher dose. (4)

Vitamin D Source Percentage of vitamin D in the body
Sun 80 - 90 percent
food 10 - 20 percent


As you can see, your vitamin D level has many important functions, which is why you have to actively work to keep it as high as possible. Especially since we just don't get enough sun in our latitudes to naturally keep vitamin D levels within the recommended norm. So definitely think about whether you want to take dietary supplements or vitamin D drops. (4.7)

As you know, vitamin D is important for calcium regulation in our body. Thus, it is essential for the bones. To avoid breaks, strengthen your muscles and simply stand more securely on your feet, you need good vitamin D levels. (10)

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