Vitamin D values: the most important questions and answers

Vitamin D Werte: Die wichtigsten Fragen und Antworten

Vitamin D is often mentioned in connection with mental wellbeing and strong bones. But the sun vitamin fulfills many other functions in the body, which are generally unknown and recede into the background. Vitamin D is essential for our immune system, the cardiovascular system and our psyche. For this reason, it is always important to have your vitamin D levels checked regularly and to spend a lot of time outdoors to be able to absorb the vitamin.

In this article we would like to explain the essential functions of the vitamin and also the signs and causes of a vitamin D deficiency. We also want to bring you closer to the long-term consequences of a vitamin D deficiency and give you some valuable tips to help you prevent and treat a vitamin D deficiency.

the essentials in brief

  • Preparations and dietary supplements should only be taken in consultation with a doctor or pharmacist and the dosage should be based on health needs. Overdose occurs only through oral intake of preparations or dietary supplements and can lead to long-term health consequences.
  • Vitamin D is absorbed to a large extent through sunlight. The proportion of vitamin D that is ingested through food is only 10 to 20%. For this reason, it is essential to spend a lot of time in the sunlight so that the daily requirement can be met.
  • Vitamin D supplements are available as tablets, drops and capsules. These can be taken when there is an extreme vitamin D deficiency and it is not possible to meet the vitamin D requirement from sunlight.

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Background: What you should know about vitamin D levels

Before we pass on tips for solving vitamin D deficiency, you should learn some background information about this vitamin.

We want to answer these frequently asked questions for you in the following paragraphs.

What is vitamin D and what does my body need it for?

According to the Robert Koch Institute, vitamin D is a generic term for fat-soluble vitamins such as vitamin D2 and vitamin D3. (5)

In addition, vitamin D is not strictly a vitamin. By definition, vitamins are organic compounds that must be obtained from food because the body cannot produce them on its own?

Vitamin D3 is absorbed through the sun.

This is not the case with vitamin D, because the body produces a large part of the vitamin itself when there is enough solar radiation. The proportion of the vitamin that is absorbed through food is only 10 to 20 percent.

Vitamin D plays an important role in the body, especially in the bones, because it promotes both the formation and the maturation of bone stem cells. Furthermore, in addition to the absorption of calcium in the intestines, it also controls the absorption of calcium and phosphate in the bones and teeth, making them strong and hard.

There are other effects of vitamin D on the body that need further research. These are the following (3,4):

  • Strengthening of the immune system
  • positive effect on the cardiovascular system and the psyche
  • Protective effects against rickets, nerve cells, against cancer
  • Preventive in vascular diseases

Finally, the involvement of the vitamin in metabolic processes and in the control of genes should also be emphasized. These functions in particular have suggested a link between chronic diseases and vitamin D in recent years. These must be researched in more detail in the future, as there is no reliable evidence to date.

How does a vitamin D deficiency manifest itself?

If there is a suspicion of a vitamin D deficiency, there are various symptoms that can occur. The symptoms manifest themselves in the fact that there is too little of the sun vitamin in the blood. There is a wide range of possible symptoms that could indicate a deficiency

Possible symptoms are (3,4):

  • hair loss
  • weakened immune system
  • Muscle and joint pain and muscle weakness
  • Bone pain and deformities
  • Neuromuscular hyperexcitability, which occurs due to calcium deficiency and in combination with migraines, paraesthesia and muscle cramps

Consequently, vitamin D deficiency results in decreased absorption of phosphorus and calcium, which compromises muscle and bone health. Since the symptoms are rather non-specific and can also indicate other clinical pictures, the family doctor should be consulted if there is a suspicion, who should consult a blood count for the diagnosis.

In the following video you will find a summary of vitamin D intake and vitamin D deficiency.

How high should the vitamin D levels in my body be?

Whether the vitamin D value is in the normal range or not should not be determined on your own, but with your family doctor. Vitamin D supply can be classified as follows: (7)

25-OH vitamin D in µg/l Meaning
less than 5 extremely severe vitamin D deficiency
5 - 10 severe vitamin D deficiency
10 - 20 Vitamin D deficiency
20 - 30 lower normal range
30 - 50 optimal vitamin D range
50 - 70 Upper normal range, only achievable with preparations
70 - 150 Vitamin D overdose
more than 150 Vitamin D intoxication

With the clarity of a blood test, the next steps can be taken, which are designed for your own health condition and thus an efficient plan to improve the vitamin D level can be worked out.

When should you see a doctor about vitamin D levels?

A doctor should usually be consulted if there is a concrete suspicion of a vitamin D deficiency or a vitamin D deficiency is revealed by a self-test. In both cases, the family doctor should be consulted afterwards.

A doctor can order treatment that suits the individual needs of the patient.

If there is any suspicion, it is advisable to see your family doctor, as they can carry out a blood test and provide clarity.

In both cases, the general practitioner will draw up a treatment plan. This can be tailored to the individual needs and health conditions of the patient. By consulting the family doctor, a harmless therapy can be carried out and overdosing through self-therapy can be ruled out.

Which diseases lead to bad vitamin D levels?

In addition to the regular deficiency symptoms that occur with a vitamin D deficiency, a deficiency can also lead to serious illnesses in the long term.

Diseases associated with vitamin D deficiency include cancer, cardiovascular, respiratory, metabolic, and autoimmune diseases(7).

People who suffer from depression have lower vitamin D levels.

In addition, vitamin D is said to have a preventive effect on diseases such as cancer. (10) It must be emphasized that it is currently unclear whether vitamin D intake or vitamin D levels are the cause of one of the diseases listed. For this reason, intensive research is required.

In this context, it was found that vitamin D plays a central role in the production of dopamine and serotonin. If patients have too few of these two in their blood, they are suspected of triggering depression. (1,2)

In this context, it is assumed that vitamin D in combination with an antidepressant can have a positive effect in the treatment of clinical depression. (9)

How does a vitamin D overdose manifest itself?

A vitamin D overdose can occur if you take vitamin D supplements that are in very high doses. A vitamin D overdose is impossible via the regular route of vitamin D intake through sunlight or diet. (8th)

Anyone who takes a daily dose of more than 100 micrograms of vitamin D must expect side effects such as kidney stones. This can be attributed to the fact that an excess of vitamin D cannot be excreted from the body, but is stored in muscle and fat tissue.

An overdose is only possible by taking preparations.

Possible symptoms of an overdose may include:

  • Extreme thirst
  • feeling weak
  • Kidney stones and damage
  • loss of appetite
  • nausea and vomiting
  • Headache
  • nervousness
  • increased urination

These symptoms can be traced back to an increased calcium level in the blood, which means that the excess vitamin D leads to increased absorption of calcium from food. As a result, calcium is increasingly released from the bones and leads to the effects mentioned above.

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  • for a healthy and balanced everyday life ✨/li>
  • automatically get 21% discount when you buy it now💰*

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*The discount is automatically applied to the product

What role do supplements play in improving vitamin D levels?

Since a vitamin D deficiency cannot be improved by changing your diet alone, your family doctor can also advise you to take vitamin D preparations and dietary supplements Vitamin D supplement

Vitamin D capsules are one type of vitamin D supplements that can be used to improve vitamin D levels. (Image Source: Michele Blackwell / Unsplash)

These are the right choice if, for example, a daily walk in the sunshine is not possible for health or professional reasons.

We have collected the most important questions about vitamin D preparations for you and answered them in the following paragraphs so that you have the most important facts at a glance.

What types of vitamin D supplements are there?

When choosing the right vitamin D supplement, there are many things to consider. Vitamin D preparations are available in different versions, which have different properties.

We have summarized the most important properties of the different preparations for you and listed them in the following sections:

Vitamin D tablets

Vitamin D tablets are comparatively cheaper and last longer than other vitamin D preparations. They also usually show rapid effectiveness, which makes them particularly attractive.

  • Inexpensive
  • Durable
  • Fast effectiveness
  • additives
  • Dubious purity
  • Lower effectiveness
  • Nevertheless, they contain production-related additives that can be difficult to swallow and also affect the purity of the product. In addition, a range of tablets show a comparatively smaller increase in vitamin D levels.

    Vitamin D drops

    Vitamin D drops are known for being particularly pure with no additives. It is also particularly easy to take due to the liquefied form and the dosage is more effective.

    • Easy ingestion
    • Individual dosing
    • Especially pure
  • Short shelf life
  • price intensive
  • Disadvantages are that they do not last as long as the other types of preparations and are also more expensive.

    Vitamin D Capsules

    The advantages of vitamin D capsules are comparatively fewer additives, which make the vitamin D purer and thereby promote improved absorption of the vitamin.

    • Fewer additives
    • Better recording
  • Possibly not vegan
  • difficulties swallowing
  • Contain no oils
  • Since the shell can be made of gelatine, they are often not vegan and vegetarian. Also, their form can lead to swallowing difficulties and if the vitamin D is not dissolved in oils, the maximum available bioavailability cannot be reached.

    When and for whom is taking vitamin D useful?

    As a rule, the vitamin D requirement can be covered by sufficient sunlight and food. Nevertheless, taking vitamin D supplements can be useful if there is an acute vitamin D deficiency.

    Sunset walk

    Vitamin D is primarily absorbed through sunlight. This is a natural way to boost vitamin D levels. (Image source: Jan Kaluza / Unsplash)

    Due to the risk of a vitamin D overdose, it is still absolutely necessary to clarify the intake of any preparations with a doctor and to have preparations prescribed or recommended by the family doctor.

    Vitamin D supplements are recommended if you rarely go outside in the sun.

    This could be, for example, people who are unable to leave the house on their own due to age or health reasons, or who work all day long which hardly leaves them the opportunity to go out into the fresh air.

    Here it is important that the opinion of a doctor is obtained, who can also suggest alternative options for treatment and can carry out the treatment of a vitamin D deficiency in accordance with the individual needs.

    What should I consider if I want to improve my vitamin D levels?

    There are different approaches to treating poor vitamin D levels, the most common being treatment with dietary supplements and preparations. These can be purchased at the drugstore or pharmacy.

    An overdose is only possible by taking vitamin D orally.

    So if you want to improve your vitamin D levels, you should consult a doctor. This can give you information about the dosage that suits your health needs and will be adjusted to you, taking into account any health conditions.

    According to the Federal Institute for Risk Assessment, the recommended maximum daily amount is 20 µg of vitamin D (= 800 iU) in food supplements and it is not advisable to take more than 100 µg (=4000 iU). (6)

    When taking products from the Internet, serious and long-term damage to health can occur again and again, since these products are usually in particularly high doses.

    In addition, there is a risk of possible interactions that could occur with the use of medication. These can be caused by the fact that vitamin D increases the calcium level and can possibly increase the effect of medication. This could lead to cardiac arrhythmias, for example.

    How effective are supplements for improving vitamin D levels?

    Preparations to improve vitamin D levels can be successful if they are taken in the correct dose. It depends on the exact adaptation to your needs, which can be discussed with a doctor or pharmacist.

    Depending on the age, health needs and the vitamin D level, the therapy with dietary supplements and preparations must be adapted and designed accordingly. Precise compliance with these specifications allows preparations to develop their effectiveness.

    If you dose the preparations yourself, it can quickly lead to an overdose. In order to achieve maximum success in improving vitamin D levels, individual needs should therefore be taken into account.

    Is it harmful to take supplements designed to improve vitamin D levels?

    Under no circumstances should vitamin D supplements be taken without consulting your family doctor. The risk of overdose and the wrong attitude towards health needs in this context would be fatal and could have long-term consequences.

    In addition, vitamin D preparations and dietary supplements are often offered, especially on the Internet, in which the ingredients have far exceeded the recommended amount of vitamin D and can therefore be harmful to the consumer.

    Excessive intake or intake of vitamin D can also quickly lead to an overdose, which can result in long-term damage to health. This damage can manifest itself, for example, in the form of a cardiac arrhythmia. For this reason, taking the preparations responsibly in consultation with experts is recommended.

    What alternatives are there to vitamin D supplements?

    In order to successfully cure a vitamin D deficiency, there are different approaches that are designed for different needs.

    We would like to explain these different options to you in more detail in the following paragraphs.


    To treat vitamin D deficiency, not only preparations and dietary supplements have to be taken. If the opportunity to come into the light of day every day, vitamin D can also be absorbed naturally and a vitamin D overdose can also be ruled out. (8th)

    In summer, three to four days a week and 15 to 30 minutes each time are usually sufficient to absorb sunlight through the skin. For this it is sufficient if the face, hands and arms are exposed to the sunlight so that an effect can be achieved.

    Nevertheless, it is essential that effective sun protection is applied so that the UVB radiation can be absorbed and converted by the body.


    An alternative way of improving vitamin D levels is to change your diet and eat foods with a high vitamin D content.

    In the following table, we want to show some foods that are particularly rich in vitamin D:

    Groceries Vitamin D in µg per 100 g
    herring 26.35 mcg
    Trout 22.00mcg
    Salmon 16.30mcg
    sardine 10.78mcg
    oysters 8.00mcg
    tuna 4.54 mcg
    processed cheese 3.13 µg
    porcini mushrooms 3.10mcg
    egg 2.93 mcg
    mushrooms 1.94 mcg

    In particular, high-fat fish and vegetables, such as mushrooms, have proven to be particularly nutritious and contain a lot of vitamin D. (8) Nevertheless, it should be emphasized that a change in diet alone is not a therapy for a vitamin D deficiency, since taking vitamin D through diet accounts for only a small percentage of vitamin D intake.


    Finally, it can be recommended that you should spend a lot of time in the sun if possible and should not arrange to take vitamin D yourself if you suspect a vitamin D deficiency. Since the symptoms are very non-specific and general, you should definitely seek advice to improve your values.

    Due to the diverse and important functions of vitamin D, you should strive for an optimal vitamin D level and have it checked by a doctor as a preventive measure. There is the possibility of a self-test or a blood test at the doctor's.


    1. Stewart & Hirani (2010). Relationship Between Vitamin D Levels and Depressive Symptoms in Older Residents Source
    2. Parker et al. (2017). Vitamin D and Depression Source
    3. (2020). Vitamin D source
    4. Nair & Maise (2012). Vitamin D: The “sunshine” vitamin source
    5. (2019). Answers from the Robert Koch Institute Source
    6. Sahota (2014). Understanding vitamin D deficiency source
    7. Holick (2007). Vitamin D deficiency source
    8. Holick (2017). The vitamin D deficiency pandemic source
    9. Khoraminya et al. (2013). Therapeutic effects of vitamin D as adjunctive therapy to fluoxetine in patients with major depressive disorder Source
    10. Lappe et al. (2007). Vitamin D and calcium supplementation reduces cancer risk Source
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