Vitamins: Vitamin D: effect simply explained

What is vitamin D?

The term vitamin D summarizes a group of fat-soluble vitamins together. These compounds are scientifically called calciferols and belong to the secosteroids. According to the Robert Koch Institute (RKI) of these compounds, vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol) are among the most important forms of the group.

Vitamin D is produced by the body itself – with the help of solar radiation. The vitamin then passes through the skin to the liver and kidneys and is converted to its bioactive form.

Vitamin D has this effect in the body

Vitamin D is important for bone metabolism, among other things. According to the German Society for Nutrition (DGE), it regulates the balance of calcium and phosphate and thus contributes to better bone stability. Vitamin D can also contribute to healthy bones, teeth and muscles.

There are a number of vitamin D supplements available for purchase. To ensure that no products with untrue food promises come onto the market, the European Food Safety Authority (EFSA) has a list of so-called “health claims”. It contains health-related statements for certain ingredients – including vitamin D. These statements are approved according to the Society for Applied Vitamin Research:

• vitamin D contributes to normal absorption/utilization of calcium and phosphorus
• vitamin D contributes to normal blood calcium levels
• vitamin D contributes to the maintenance of normal bones
• vitamin D contributes to the maintenance of normal muscle function
• vitamin D contributes to the maintenance of normal teeth
• vitamin D contributes to the normal functioning of the immune system
• vitamin D has a function in cell division

Important to note: Although vitamin D is good for the immune system and the effect has been scientifically confirmed, this does not mean that dietary supplements with vitamins automatically have a positive effect on the immune system. If the body is already sufficiently supplied with vitamin D, taking it can even be harmful.

Vitamin D: what are the symptoms of an overdose?

According to the RKI, vitamin D can be stored in muscle and fat tissue. A vitamin D overdose through the body’s own production is not possible, but food supplements can lead to symptoms of poisoning. According to the RKI, these include the following symptoms:

• nausea
• loss of appetite
• Stomach cramps
• Vomit

In severe cases, an overdose can even lead to death, writes the RKI.

Is there a vitamin D deficiency in Germany?

There are relatively few foods in which vitamin D can be found. One myth in particular persists: that avocados contain vitamin D. That’s not the case. The values ​​were published according to the Max Rubner Institute and were based on measurements in the laboratory. The values ​​have now been adjusted.

The main source of vitamin D comes from the skin. But it needs sunshine for that. Nevertheless, according to the DGE, “the majority of the population does not have a vitamin D deficiency”. According to Publication of the RKI from 2016, around 30.2 percent of adults do not have enough vitamin D. 38.4 percent of Germans, on the other hand, have sufficient reserves in their bodies. A deficiency can be determined via the blood values ​​and treated accordingly with preparations.

How much vitamin D does the body need per day?

The DGE recommends staying outside for a total of five to 25 minutes a day. It is important for the formation of vitamin D that face, hands and arms are as uncovered as possible. However, the need differs depending on the skin type, so it is important to pay attention to it when sunbathing. The Federal Office for Radiation Protection states that the skin is only exposed to half of the “sunburn-effective UV dose”. As a reference value, you take the time in which the skin would suffer a sunburn and halve the value. Different times apply to light main types (1 to 3) than to darker skin types (4 to 6). The DGE provides an overview of daily intake by age:

* Estimates