Vitamin D is a fat-soluble vitamin that our body can synthesize under the influence of sunlight. Nevertheless, recent studies indicate that more and more people have too little vitamin D in their blood. However, vitamin D deficiency can have devastating consequences: as vitamin D plays a key role in the regulation of the calcium balance, deficiency can lead to skeletal instability. However, not only a vitamin D deficiency, but also an overdose has a negative effect on our body.
Vitamin D regulates the calcium balance
Vitamin D is a collective term that includes multiple compounds. Of these, vitamin D2, which is found in plants and fungi, and vitamin D3, which is only found in animal foods, are of particular importance to us humans.
In the body, vitamin D is involved primarily in the regulation of the calcium and phosphate balance. Vitamin D ensures that dietary calcium can be absorbed better and supports the incorporation of calcium into the bones.
In addition, vitamin D is also involved in the regulation of calcium levels in the blood: If the calcium level decreases, calcitriol can be produced from an inactive precursor of vitamin D. Calcitriol then ensures that calcium is released from the bones and the calcium level in the blood rises again. This ensures that calcium is available for vital metabolic functions such as the transmission of nerve cell stimuli or the work of the muscles.
Vitamin D strengthens the immune system
In addition to the regulation of the calcium balance, vitamin D also plays an important role in strengthening the immune system. How exactly vitamin D contributes to the defense against pathogens, however, is not yet clear.
However, it is believed that certain cells of the immune system - the T lymphocytes - are mandated by vitamin D to get rid of the pathogens. If there is not enough vitamin D in the body, the T-lymphocytes can not respond to the pathogens and these can nest and multiply without much resistance in the body.
Vitamin D prevents cardiovascular disease
However, vitamin D should not only strengthen the body's defense against typical infectious diseases such as colds, flu or pneumonia, but also have an anti-cancer effect: recent studies indicate that with sufficient vitamin D supply to the risk of certain types of cancer such as breast cancer or colon cancer um up to 50 percent lower than those with a vitamin D deficiency.
However, vitamin D should not only have a preventive effect, but also have a positive effect on the healing process in the event of an already outbreak of cancer. Thus, vitamin D is said to inhibit the formation of metastases and tumor growth. This hypothesis has been reviewed in studies so far for colon cancer, prostate cancer, breast cancer, lung cancer and skin cancer. The studies indicate that the chances of survival in one of these cancers increase significantly due to a high vitamin D level.
Also, the risk of cardiovascular disease should be significantly reduced by enough vitamin D in the blood. For example, one study found that people over the age of 50 who had vitamin D deficiency had a significantly higher risk of developing cardiovascular disease. Further studies are still pending here. The same applies to the thesis that an adequate supply of vitamin D can reduce the risk of diseases such as diabetes or multiple sclerosis.
Vitamin D in food
Vitamin D is found in food especially in cod liver oil and in fish. High-fat fish such as herring, sardine or salmon are particularly rich in the vitamin. If you do not like fish, you can also use dairy products and eggs as well as various types of mushrooms. Here are especially mushrooms and shiitake mushrooms rich in vitamin D. However, their vitamin D content is far below that of fatty fish.
In addition to the foods mentioned, vitamin D can also be supplied to the body via dietary supplements.
How much vitamin D should be absorbed by the body to protect it from disease is a matter of debate among scientists. Currently, the recommended daily dose of vitamin D for children and adults is 20 micrograms, according to the German Nutrition Society. Infants under one year should take ten micrograms daily.
For example, 20 micrograms of vitamin D are contained in the following foods:
- 80 grams of herring
- 125 grams of salmon
- 6 to 7 grams of cod liver oil
- 645 grams of porcini mushrooms
- 600 grams of avocado
In general, it should be noted that the intake of vitamin D via food plays only a minor role. The majority of the need for vitamin D is already covered by the production of endogenous vitamin D. In case of deficiency, relevant amounts of vitamin D are best administered via dietary supplements.
Vitamin D content in the blood
Vitamin D can not only be supplied by food, but can also be synthesized by the body itself. Under the influence of sunlight (UV-B light), cholesterol is converted to a precursor of vitamin D. This process represents the much more important source of supply compared to food intake: up to 90 percent of the vitamin D present in our body is synthesized in this way.
Since vitamin D is mostly produced by the body itself, it is not a classic vitamin. By definition, vitamins are only those substances that the body can not produce itself.
Normal is a vitamin D content of at least 20 to 30 nanograms of vitamin D per milliliter of blood. How high the vitamin D level in the blood, however, ideally should be exactly, is controversial among experts. However, some studies also indicate that vitamin D can counteract cancer only at a level of 32 nanograms per milliliter of blood. Such values can be achieved either by having a regular stay outdoors or by taking vitamin supplements.
How much vitamin D is produced while outdoors depends on several factors. This includes:
- skin pigmentation
- Intensity of sunlight
In babies and infants, as well as during pregnancy and lactation, the need for vitamin D is increased. During this time, special care should be taken to ensure that the vitamin D level does not decrease too much.