Where is vitamin D in it: everything you need to know

Wo ist Vitamin D drin: Alles was du wissen musst

Do you sometimes feel listless, tired or powerless? Or have you always wondered what vitamin D actually is, what it can do and where it is found? Then this article could be just the thing for you.

Because here we deal in detail with the vitamin and show you where vitamin D is in it. Vitamin D is important in connection with physical health and is also responsible for many processes in the body. For example, it helps maintain bone health.

With this article we want to introduce you to vitamin D in more detail, take a closer look at the essential functions, explain what kind of vitamin this is, how it gets into our body, why it is called the sun vitamin and what can happen with a vitamin D deficiency.

As the article continues, you will learn where vitamin D is in so you can keep your levels up. After reading, you should be sufficiently informed about vitamin D and be prepared for the cold season. Have fun while reading.

the essentials in brief

  • Vitamin D cannot be produced by the body, but is produced in the skin by exposure to the sun. The body can store the vitamin so that you can maintain your vitamin D level even in the colder seasons.
  • In the case of an acute vitamin D deficiency, preparations can be used. These can be taken in various forms, such as tablets or capsules.
  • You can also get vitamin D in small amounts from food. There aren't many foods that contain vitamins. It is all the more important to find out which foods you can absorb vitamin D from.

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Definition: What is vitamin D?

The term vitamin D describes a unit of fat-soluble vitamins. Vitamin D mostly comes from plants and cannot be produced by the body on its own. The vitamin can only be produced in the skin with the help of UV-B rays from the sun. It is therefore often referred to as the sun vitamin. In the event of a deficiency, the vital substances should be taken through food or preparations.

A special feature of vitamin D is that, in contrast to vitamins A or B, it is not only responsible for a reaction in the metabolism, but also represents the precursor of a hormone. This allows it to control processes in the body.

Like other vitamins, vitamin D can appear in the body in different chemical forms. Two forms of it are: Vitamin D3 and D2:

  • Vitamin D3: This is the form of the vitamin that is formed in the skin by the sun's rays or can also be found in animal foods.
  • Vitamin D2: This form enters our body through plant foods, but does not appear naturally in the human metabolism.

Both forms can be actively converted into vitamin D in the human body. (1)

Background: What you should know about vitamin D

In this section we want to inform you as best we can about the vitamin.

solar radiation

Vitamin D is also known as the sunshine vitamin - and rightly so. We get about 80% of our Vitmins D requirement from sunlight. (Image source: Jeremy Bishop, unsplash)

We have prepared a few questions for you that might interest you. After this part of our article, you will have a sound basic knowledge of vitamin D.

What effect does vitamin D have on our body?

Vitamin D does not work in the body like other vitamins. The effect can be compared to that of a hormone. It can stimulate numerous processes in the body. Almost all areas of health are dependent on vitamin D.

Vitamin D can influence the following areas or aspects:

  • On the immune system
  • On the heart and the circulatory system
  • On the mineral balance or
  • On the nerves or the brain

In general, vitamin D helps us feel fit and vital. This depends, among other things, on a sufficient blood level. Vitamin D is given in micrograms. If the blood contains between 35 and 60 ng/ml, one can speak of a sufficient or normal value. But sufficient supply from the sun or cofactors also play an important role. (2)

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Which cofactors play an important role in vitamin D?

Vitamins are not medicines that can help against a disease. Rather, they are a component of various interconnected processes. The human state of health depends on this, because if one of these processes is disturbed, a disease can develop. Vitamin D is no exception:

Vitamin D can only fulfill its full effect if the body is also supplied with other nutrients that contribute to the effect of the vitamin.

Health therefore depends on the cooperation of nutrients. The vitamin can develop its full effect when the blood level is right and in combination with vitamin A or K2 and magnesium, for example. (3)

How does vitamin D get into our body?

Vitamin D can be absorbed by the body in a variety of ways. Sunlight is probably the most important source of this. Vitamin D is formed in the skin through exposure to the sun. This is ensured by the UV-B radiation, which is also responsible for the tan of the skin. (4)

The rays penetrate into the uppermost layers of the skin and are transformed there by photolysis into a previtamin D3, which is then subsequently converted into vitamin D3.

Vitamin D can find its way into our body in a variety of ways.

The vitamin is then converted in the liver into 25-OH vitamin D, the form of vitamin D that can be measured in a blood test. Finally, the actual hormone form is formed by the cell itself as required. (5)

In areas where the sun shines less often or where people don't get much sun on their skin due to unusual working hours, vitamin D supplements can be used.

Some prefer going to a tanning bed to maintain vitamin D levels. Everyone has to decide for themselves. On the one hand, technology has developed and solariums are now less aggressive, but doctors do not recommend visiting the solarium. The UV rays are far too intense and increase the risk of skin cancer. (6)

Vitamin D can also enter our bodies in the form of tablets or capsules, or through our daily food intake.

Where is vitamin D in?

If vitamin D cannot be obtained from food, it is possible to use vitamin D supplements. These preparations are available in a variety of forms. Vitamin supplements can be taken as oils, drops, tablets or capsules.

Vitamin D tablets

There are a variety of different supplements that you can take to prevent vitamin D deficiency. (Image source: Kayla Maurais, unsplash)

A simple form of administration are the drops. The vitamin can not only be easily applied to the tongue, but can also be quickly absorbed and processed by the body.

Drops or capsules have fewer additives and are therefore most suitable for ingestion.

How are vitamin D levels measured?

A blood test is necessary to find out how the vitamin D level is. It examines how much vitamin D is circulating in the blood. More specifically, the 25-OH vitamin (calcidiol) in the blood is measured in milliliters. Vitamin D can be specified in two units. The most common specifications are ng/ml and nmol/l. (7)

The table shows from when one can speak of a deficiency to an overdose.

interpretation value ng/ml value nmol/L
Shortage greater than 20 greater than 50
undersupply 20-30 50-75
normal range 30-60 75-150
High value 60-90 150-225
overdose greater than 150 greater than 375

How much vitamin D does a person need?

The question of the right dosage of vitamin D is more complex than you think. It depends on many different factors. Depending on how much vitamin D has already been produced by the skin or the weather conditions, the further requirement has to be met in different ways.

In addition, it also depends on individual factors how much vitamin D the body needs. However, attention can be paid to a few variables that can help refine the right dosage. These factors are: the state of deficiency, sun exposure, time of year, age and the extent of disease.

How does a vitamin D deficiency manifest itself?

In the short term, a vitamin D deficiency can hardly have any side effects. However, a long-term lack of vitamin D can significantly affect the overall health of the body.

The table lists some symptoms that can be caused by a lack of vitamin D.

Area symptom
cellular health Poor performance, tiredness, difficulty concentrating, dizziness, headache
Bone Increased risk of fractures, rickets, osteoporosis (bone loss), osteomalcia (bone softening)
immune system Immune deficiency, susceptibility to infections, respiratory diseases
cardiovascular system Cardiac arrhythmias, circulatory weakness
muscles Muscle weakness, cramps, muscle pain
nerves and brain Nerve pain, depression, dementia

However, these late effects are not always due to vitamin D.

How high should the vitamin D daily requirement be?

It is quite difficult to recommend the actual daily requirement for vitamin D as there is no actual value. One of the reasons for this is that, unlike other vitamins, vitamin D cannot be absorbed by the body from just one source.

In summer, the need for the vitamin can be absorbed through daylight.

Exercise in the fresh air helps in summer. Of course, those who cannot go outside due to work conditions or health reasons are excluded from this.

In winter, the sun's rays may not be sufficient. If the natural vitamin D store has been used up, preparations or the solarium can be used. (8th)

Vitamin D: Foods that contain a lot of vitamin D

You can use a wide variety of foods to maintain your vitamin D level.

Below you will find a list of a wide variety of foods that contain vitamin D. We also clarify which foods contain the most vitamins, how much vitamin D should you consume and which foods are the best sources to consume vitamin D? You can find the answers here. Here we go.

Vitamin D in foods

There are two different types of foods that contain vitamin D. These differ in chemical composition:

  • Animal foods contain vitamin D3 and
  • Plant foods contain vitamin D2

Both vitamin D variants can have health effects. On the one hand, vitamin D3 is the form of vitamin D that the body can make and on the other hand, the body can convert vitamin D2 into D3.

Most vitamin D is generated by exposure to the sun. Food is of secondary importance. Fish contains a particularly large amount of vitamin D.

In order to cover your vitamin D requirement solely through the increase in food, you would have to consume a lot of fish every day, for example. Especially for people whose living conditions do not allow them to spend a lot of time in the sun, the increase in vitamin D through food can cover or improve the need. This can prevent a vitamin D deficiency in the winter months.

Animal foods contain a particularly large amount of vitamin D:

  • Fatty fish such as salmon or herring
  • offal like liver
  • egg
  • cheese and butter

In plant-based foods, you can find vitamin D primarily in:

  • avocado
  • mushrooms
  • margarine

In the following table we want to give you an overview of where there is a particularly large amount of vitamin D in it. We have specified micrograms/100g as the unit. Since vitamin D3 is more effective than vitamin D2, the values ​​can only be compared to a limited extent. Nevertheless, you get a good overview and can compare the foods with each other to choose your favourites:

Groceries Vitamin D content in ug/100g
Chlorella (freshwater algae) D2 316
Cod liver oil D3 300
IAal (smoked) D3 90
Salmon D3 16
Sardines D3 10
Avocado D2 5
Tuna D3 4.5
Porcini mushrooms D2 3

However, most vitamin D is absorbed into the skin through exposure to the sun. The subsequent synthesis adequately covers around 80 to 90 percent, and thus most of the requirement. Especially in the summer months, it is possible that the absorption of vitamin D from the sun is up to ten times greater than that from vitamin D through food.


Vitamin D is a very special vitamin, as it cannot be produced by the body on its own, but can only be formed with the help of the sun's rays and ultimately bound to our cells. It is not for nothing that it is also called the sun vitamin and has been known to most people since their early childhood. A lack of vitamin D can lead to health problems in the long term. That's why it's important to keep an eye on your vitamin D levels.

In this article you learned where vitamin D is found, for example in preparations or in food. However, it is important to note that most vitamin D is generated by exposure to the sun's rays on our skin and then absorbed into our bloodstream.

Ingesting vitamin D only through food requires a strict and complex diet and is almost theoretically feasible. Nevertheless, you can maintain your vitamin D level by making a well-informed selection of foods.


  1. Meehan, M., & Penckofer, S. (2014). The Role of Vitamin D in the Aging Adult. Journal of aging and gerontology, 2(2), 60-71. https://doi.org/10.12974/2309-6128.2014.02.02.1
  2. Zittermann, Armin; Gummert, Jan F. 2010. "Nonclassical Vitamin D Actions." Nutrients 2, no. 4: 408-425.
  3. Masterjohn C. Vitamin D toxicity redefined: vitamin K and the molecular mechanism. Med Hypotheses. 2007;68(5):1026-1034. doi:10.1016/j.mehy.2006.09.051
  4. Chapuy MC, Preziosi P, Maamer M, et al. Prevalence of vitamin D insufficiency in an adult normal population. Osteoporos Int. 1997;7(5):439-443. doi:10.1007/s001980050030
  5. Norman, Anthony. (1998). Sunlight, season, skin pigmentation, vitamin D, and 25-hydroxyvitamin D: Integral components of the vitamin D endocrine system. The American journal of clinical nutrition. 67. 1108-10. 10.1093/ajcn/67.6.1108.
  6. iobid resource; Kipshoven, Christoph: Cross-sectional study to assess the vitamin D status in the population in Germany (DEVID study); presented by Christoph Kipshoven; 2010; urn:nbn:de:hbz:38m-0000002566; HT016404127; Cologne, Univ., Diss., 2010
  7. Stamp TC, Haddad JG, Twigg CA. Comparison of oral 25-hydroxycholecalciferol, vitamin D, and ultraviolet light as determinants of circulating 25-hydroxyvitamin D. Lancet. 1977;1(8026):1341-1343. doi:10.1016/s0140-6736(77)92553-3
  8. Holick MF, Binkley NC, Bischoff-Ferrari HA, et al. Evaluation, treatment, and prevention of vitamin D deficiency: an Endocrine Society clinical practice guideline [published correction appears in J Clin Endocrinol Metab. 2011 Dec;96(12):3908]. J Clin Endocrinol Metab. 2011;96(7):1911-1930.
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