Vitamin D is the name for several fat-soluble vitamins. The most important form is vitamin D3 or cholecalciferol. Vitamin D contributes to bone mineralization and the normal function of the immune system, among other things. The body can produce it itself if sunlight is available to it. If the body’s own synthesis is not sufficient, it may be necessary to take an appropriately dosed vitamin D supplement to avoid a deficiency.
Vitamin D3 at a glance
- Vitamin D is the name given to a group of fat-soluble compounds, of which vitamin D3 is the most important.
- Vitamin D, for example, makes a decisive contribution to the mineralization of bones and teeth as well as to normal calcium levels in the blood.
- The body can produce vitamin D3 itself if it has enough UV-B radiation from the sun.
- If the body’s own synthesis is missing, all people aged one year and over have a daily requirement of 20 micrograms, according to the DGE.
- Both a deficiency and an excess of vitamin D can have serious consequences for health.
What is vitamin D?
Vitamin D is a collective term for a group of fat-soluble compounds. Although they are classified as Vitamins, they are actually prohormones. This is because the body uses them to form the hormone calcifediol from them.
What is the difference between vitamin D and D3?
There are different forms of vitamin D. A distinction is made between vitamin D2 and vitamin D3. D2, also known as ergocalciferol, is produced by plants. Vitamin D2 (ergocalciferol) must be converted into 25-hydroxyvitamin D in the liver and then into the active form 1,25-dihydroxyvitamin D in the kidneys.
Vitamin D3 is also known as cholecalciferol . It is the form of the vitamin that is produced by humans and animals. Cholecalciferol is more effective than ergocalciferol and is therefore commonly found in vitamin D supplements.
What is vitamin D3 good for?
Vitamin D or vitamin D3 has various important functions in the body. The fat-soluble vitamin is important, among other things, for the absorption and utilization of calcium and phosphorus as well as for the maintenance of normal bones and teeth.
In addition, vitamin D also contributes to, for example:
- a normal calcium level in the blood,
- normal function of the immune system and
- normal muscle function.
Does vitamin D protect against diseases?
Vitamin D is sometimes said to protect against numerous diseases. In addition to Diabetes, this also includes e.g. Multiple Sclerosis and cancer. However, caution should be exercised with such statements, as they have not yet been scientifically proven.
How does the vitamin D supply work?
Unlike most other nutrients, the body can produce vitamin D3 very well itself. To do this, it converts cholesterol into provitamin D3. From the provitamin D3, previtamin D3 and last but not least vitamin D3 are formed in the skin with UV-B rays.
In addition to the body’s own synthesis, you also take in some vitamin D with your diet. However, this only plays a subordinate role in terms of needs-based care. Overall, foods containing vitamin D only contribute about 10 to 20 percent to meeting the requirement.
Was ist der Unterschied zwischen Vitamin D und D3?
gibt verschiedene Formen von Vitamin D. Man unterscheidet zwischen Vitamin D2 und Vitamin D3. Das auch als Ergocalciferol bekannte D2 wird von Pflanzen gebildet. Vitamin D2 (Ergocalciferol) muss in der Leber in 25-Hydroxyvitamin D und anschließend in der Niere in die aktive Form 1,25-Dihydroxyvitamin D umgewandelt werden.
Vitamin D3 wird auch als Cholecalciferol bezeichnet. Es handelt sich dabei um die Form des Vitamins, die von Menschen und Tieren gebildet wird. Cholecalciferol ist wirksamer als Ergocalciferol und daher üblicherweise auch in Vitamin-D-Präparaten enthalten.
Wofür ist Vitamin D3 gut?
Vitamin D bzw. Vitamin D3 hat im Körper verschiedene wichtige Funktionen. Das fettlösliche Vitamin ist unter anderem wichtig für die Aufnahme und Verwertung von Calcium und Phosphor sowie für die Erhaltung normaler Knochen und Zähne.
Außerdem trägt Vitamin D beispielsweise auch bei zu:
- einem normalen Calciumspiegel im Blut,
- einer normalen Funktion des Immunsystems und
- einer normalen Muskelfunktion.
Schützt Vitamin D vor Krankheiten?
Vitamin D wird bisweilen nachgesagt, dass es vor zahlreichen Erkrankungen schützen soll. Neben Diabetes gehören dazu z.B. auch Multiple Sklerose und Krebs. Bei solchen Aussagen ist jedoch Vorsicht angebracht, da sie bislang nicht wissenschaftlich belegt sind.
Wie funktioniert die Vitamin-D-Versorgung?
Im Gegensatz zu den meisten anderen Nährstoffen, kann der Körper Vitamin D3 sehr gut selbst bilden. Zu diesem Zweck wandelt er Cholesterin in Provitamin D3 um. Aus dem Provitamin D3 wird in der Haut mit UV-B-Strahlen dann Prävitamin D3 und zu guter Letzt Vitamin D3 gebildet.
Zusätzlich zur körpereigenen Synthese nimmt man auch etwas Vitamin D mit der Ernährung auf. Hinsichtlich einer bedarfsgerechten Versorgung spielt das aber nur eine untergeordnete Rolle. Insgesamt tragen Vitamin-D-haltige Lebensmittel nur ungefähr 10 bis 20 Prozent zur Deckung des Bedarfs bei.
Where is a lot of vitamin D in it?
Most foods do not contain significant amounts of vitamin D. Therefore, it is almost impossible to cover the daily requirement with diet alone. In addition to cod liver oil, the few exceptions include some fatty fish and seafood. Liver, eggs and some dairy products contain at least some vitamin D.
Plant-based foods are usually not suitable as a supplier of the fat-soluble vitamin. They not only have a low vitamin D content. Apart from that, they also contain only vitamin D2, which is less effective in the human body than vitamin D3.
Examples of foods containing vitamin D (μg per 100 g)
- Eel 20
- Oysters 8
- Eggs 2.9
- Emmentaler 1.1
- Gouda 1.3
- Herring 25
- Chicken liver 1,3
- Salmon 16.3
- Beef liver 1,7
- Sardines 11
How much vitamin D should you consume daily?
If the body does not produce vitamin D, it is dependent on the supply from outside. The DGE (German Society for Nutrition) states the daily requirement for this case as 20 micrograms , which corresponds to 800 IU (international units). The value applies to all people aged one year and older. According to the estimates of the DGE, infants have a daily requirement of 10 micrograms. This corresponds to the usual dose they receive as part of rickets prophylaxis.1
What are the causes of vitamin D deficiency?
Since the body depends on the sun for the production of vitamin D3, a deficiency is mainly caused by too little sunlight. In northern and central Europe, the sun often does not shine enough to ensure sufficient endogenous synthesis due to climatic conditions, especially in winter.
An additional problem in this context is the fact that nowadays the majority of people work indoors such as offices or factories. As a result, they are sometimes only sporadically exposed to the sun even in the summer months.
Risk groups for a deficiency
In principle, all people can develop a deficiency of vitamin D. However, the following population groups have an increased risk of it:
- People who suffer from chronic diseases of the digestive system, liver or kidneys
- People whose vitamin D metabolism is impaired by treatment with certain medications
- Dark-skinned people, as their skin allows less UV radiation to pass through
- Seniors, as they often spend more time indoors and their body’s synthesis is limited
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What are the effects of vitamin D3 deficiency?
If the body is not sufficiently supplied with vitamin D, bone health, the immune system and the function of the muscles, among other things, suffer. This can manifest itself with a number of deficiency symptoms and have serious consequences for health in the long run.
Symptoms of vitamin D deficiency
Depending on the duration and severity, a vitamin D deficiency can manifest itself with the following symptoms, for example:
- Myasthenia
- Muscle cramps
- Increased susceptibility to infections
- Hair loss
- Migraine
Long-term consequences of vitamin D deficiency
The consequences of a permanent deficiency include, in particular, decreasing bone density. If the undersupply is not counteracted, the risk of bone fractures and diseases such as osteoporosis or Osteomalacia.
Children can have a severe deficiency of rickets. Among other things, the disease leads to impaired mineralization and deformation of the bones. To avoid this, the daily administration of a vitamin D supplement is common for infants.
How can a vitamin D deficiency be remedied?
An existing deficiency can be remedied in two different ways.
- At least in the warmer and, above all, sunnier months of the year, regular stays outdoors can promote the body’s own production of vitamin D. Of course, it is important to pay attention to the respective skin type and to avoid sunburn due to too long sunbathing.
- A suitably dosed dietary supplement ensures that vitamin D levels are normalised quickly and reliably, regardless of the season. Very high-dose preparations are usually not necessary for this purpose and are only recommended to a limited extent due to the risks.
What are the causes of vitamin D excess?
Just like too much, too little vitamin D can also be harmful to health. In principle, an oversupply only occurs through the uncontrolled intake of high-dose vitamin D preparations. The vitamin D content of foods is far too low to cause side effects. The body’s own synthesis is simply stopped when needed. Even long sunbaths in summer do not lead to an excess, even if they should of course be enjoyed with caution or appropriate sun protection due to the risks to skin health.
What happens if you take too much vitamin D3?
In contrast to water-soluble vitamins such as Vitamin C the body can store fat-soluble vitamins well. If you regularly take a high-dose vitamin D supplement, the concentration in the organism continues to increase. This makes both an acute overdose and a chronic excess possible.
If there is an oversupply of vitamin D, more calcium is absorbed from food. This can lead to an increase in calcium levels in the blood and deposits in organs.
This can lead to hypercalcemia. This condition is responsible for the side effects associated with the overdose.
Side effects of too much vitamin D
A vitamin D overdose can manifest itself with the following symptoms, among others:
- Weight loss
- Constipation
- Nausea and vomiting
- Severe thirst and frequent urination
- Fatigue
- Nervousness
- Muscle pain and headaches
- Arrhythmias
- Hypertension
Long-term consequences of vitamin D oversupply
An oversupply of vitamin D can not only cause short-term side effects. If it is not treated promptly, it can have serious consequences for health in the long run.
Possible long-term consequences are, for example:
- the formation of kidney stones,
- kidney damage to kidney failure,
- calcified blood vessels and organs, and
- an increased risk of osteoporosis.
How can a vitamin D surplus be remedied?
If symptoms of oversupply occur, those affected must stop taking their vitamin D supplement immediately. As the excess in the body decreases, the side effects subside again. Additional treatment with medication is usually only necessary in the case of a very high overdose.
What is the maximum daily dose?
The EFSA, the authority responsible for food safety in the European Union, specifies a maximum daily dose of 100 micrograms for vitamin D for adults. Under normal circumstances, even the regular intake of five times the daily requirement should not cause any problems.2
The German BFR (Federal Institute for Risk Assessment) recommends a maximum amount of 20 micrograms per recommended daily intake for vitamin D in food supplements. For fortified foods, the recommendations vary between 1.5 and 10 micrograms per 100 grams, depending on the product.3
When should you determine vitamin D status?
Measuring the vitamin D level in the blood can be useful in many situations. It helps to detect a deficiency or excess in a timely manner. This makes it possible to take countermeasures at an early stage and to ensure a needs-based vitamin D supply.
To determine the vitamin D status, the concentration of 25-hydroxyvitamin D is measured in the serum. This is a vitamin D precursor formed by the liver. The blood sample required for the test can be taken either at the doctor’s office or at home with an appropriate test kit.
How useful is vitamin D as a dietary supplement?
Many people are affected by an inadequate vitamin D supply. This is also shown, for example, by the National Consumption Study II of the Max Rubner Institute. According to the results of the study published in 2008, 91 percent of all women and 82 percent of all men in Germany do not reach the recommended daily vitamin D intake.4
A dietary supplement can help to compensate for low vitamin D levels and counteract deficiency symptoms. To avoid side effects, it is essential to ensure a dosage that is appropriate to your needs. High-dose preparations are not useful in most cases.
Important to know
Are you not a specialist and have complaints, certain diseases or suspect deficiency symptoms? Then please be sure to consult a doctor to discuss this.
- 1 Deutsche Gesellschaft für Ernährung e.V.: Schätzwerte für eine angemessene Vitamin D-Zufuhr bei fehlender endogener Synthese (Stand: 2012). URL: https://www.dge.de/wissenschaft/referenzwerte/vitamin-d/ (zuletzt aufgerufen am: 03.10.2024).kaltungen (zuletzt aufgerufen am: 19.09.2024).
- 2 European Food Safety Authority: Overview on Tolerable Upper Intake Levels as derived by the Scientific Committee on Food (SCF) and the EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA) (Veröffentlichung: Juni 2024). URL: https://www.efsa.europa.eu/sites/default/files/2024-05/ul-summary-report.pdf (zuletzt aufgerufen am: 03.10.2024).
- 3 Bundesinstitut für Risikobewertung: Höchstmengenvorschläge für Vitamin D in Lebensmitteln inklusive Nahrungsergänzungsmitteln (Veröffentlichung: 2021). URL: https://www.bfr.bund.de/cm/343/hoechstmengenvorschlaege-fuer-vitamin-d-in-lebensmitteln-inklusive-nahrungsergaenzungsmitteln.pdf (zuletzt aufgerufen am: 04.10.2024).
- 4 Max Rubner-Institut: Ergebnisbericht, Teil 2 Nationale Verzehrsstudie II (Veröffentlichung: 2008). URL: https://www.mri.bund.de/fileadmin/MRI/Institute/EV/NVSII_Abschlussbericht_Teil_2.pdf (zuletzt aufgerufen am: 04.10.2024).
