Vitamin D is important for bone mineralization, among other things. The body’s own production of vitamin D depends on sufficient UV-B radiation from sunlight. A lack of sun exposure, such as through long periods of time indoors or during the winter months, can significantly reduce vitamin D formation in the body. This leads to a deficiency that manifests itself with numerous complaints and can have serious consequences for health in the long run. To remedy an existing vitamin D deficiency, it is necessary to take vitamin D as a dietary supplement. 

What is vitamin D? 

Vitamin D is a collective name for several fat-soluble substances with similar effects. Strictly speaking, these are not vitamins, but prohormones. This is because the hormone calcifediol is formed from them in the body  . 

Regardless of this, a distinction is made between two types of vitamin D: 

1. Vitamin D2 or ergocalciferol is the form formed by plants. It must first be converted in the human body and is therefore less effective. 
2. Vitamin D3 or cholecalciferol is the form formed by animals and humans. Since it does not have to be converted first, it is more effective than D2. 

What does the body need vitamin D for? 

Vitamin D has numerous important tasks in the human body. Among other things, it makes a decisive contribution to the normal maintenance of bones and teeth by promoting the absorption of phosphorus and calcium and regulating calcium levels in the blood. 

Apart from that, vitamin D is also important for, for example: 

• normal muscle function, 

• the immune system and 

• cell division. 

How is the body supplied with vitamin D? 

Most vitamin D is produced by the body itself. To do this, it first converts cholesterol to provitamin D. From this, it first forms previtamin D and then vitamin D in the skin with the help of UV-B radiation from the sun.

Part of the vitamin D requirement is also  covered by diet. However, the supply with food only contributes to the supply to a very limited extent. Depending on the diet, food provides between 10 and 20 percent of the daily requirement. 

What is the daily vitamin D requirement? 

If the body’s own synthesis fails to materialise, a sufficient supply of vitamin D from the outside is required. According to the reference values of the DGE (German Nutrition Society), children from one year of age and adults in this case need 20 micrograms daily. For infants, the DGE specifies the daily vitamin D requirement at 10 micrograms. This is also the usual dose for rickets prophylaxis.1 

How does vitamin D deficiency occur? 

The body can only produce vitamin D if sunlight or UV-B radiation is available to it. However, this is not always the case in central and northern European countries. Especially in the winter months, the sun is often not enough to ensure sufficient body production of vitamin D. 

To make matters worse, most people no longer work outdoors, but in offices or factories. As a result, they often do not get enough sun even in summer and can also develop a vitamin D deficiency more easily at this time of year. 

Who is particularly susceptible to a deficiency?  

In general, all people can be affected by a vitamin D deficiency. However, certain factors can significantly increase the risk. 

The following groups of people are particularly susceptible to a deficiency: 

• People with dark skin types, as the strong pigmentation allows less UV radiation to pass through 

• Older people who produce less vitamin D and are also less likely to spend time outdoors. 

• People whose vitamin D metabolism  is disturbed by taking certain medications 

• People who  suffer from chronic  liver or kidney disease 

• People who have chronic bowel diseases such as Crohn’s disease lead to reduced nutrient absorption 

What is a vitamin D predator? 

Vitamin D robbers are substances that  can impair the metabolism of vitamin D. These include, for example, cortisone and medications used to treat epilepsy, as well as St. John’s wort, which is used as a natural mood enhancer.