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Vitamin D

Vitamin D occupies a special position among the vitamins, as it can be formed by the body itself under the influence of sunlight in the skin. Its intake through food is usually low, as most foods contain only little vitamin D. It is found in significant quantities in fatty sea fish, eggs and mushrooms, for example.

Vitamin D plays an important role in calcium and phosphate metabolism and thus for the development and maintenance of healthy bones. It also strengthens muscles and contributes to a well-functioning immune system. A sufficient vitamin D supply is therefore important.

How much vitamin D the body produces varies greatly from person to person and depends on numerous factors such as skin type, age and season. In Germany, about 54 % of children and adolescents and 44 % of adults have an adequate vitamin D status. This is said to be the case when the blood serum concentration of the marker for vitamin D supply (25-hydroxyvitamin D) is at least 50 nanomoles per litre (nmol/L). About 33 % of children and adolescents and 41 % of adults have concentrations in the suboptimal range (30 to below 50 nmol/L). About 13 % of children and adolescents and 15 % of adults have vitamin D deficiency - the concentration of 25-hydroxyvitamin D in the blood serum is below 30 nmol/L.

A good vitamin D supply can be achieved by regularly exercising in fresh air with sufficient sunlight. It is recommended to expose the face, hands and arms to the sun uncovered and without sunscreen for a few minutes two to three times a week. However, sunburn should always be avoided.

The risk groups for an undersupply include people who hardly (or not at all) spend time outdoors or - for example for cultural or religious reasons - only go outside with their body completely covered. Also, people with a dark skin colour (high melanin content) have a higher risk for vitamin D deficiency as they can produce less vitamin D than people with light skin. Another important risk group is older people, since vitamin D formation decreases significantly with age and there are also mobility-impaired, chronically ill and care-dependent people in the older population who (cannot) spend much time outdoors, if at all. However, infants are also among the risk groups for a vitamin D deficiency, since on the one hand the vitamin D content of breast milk is very low and on the other hand infants should generally not be exposed to direct sunlight, since their skin's own protective mechanism has yet to develop.

To ensure an adequate vitamin D supply in infants, they should receive 400-500 IU (10-12.5 μg) of vitamin D daily as a supplement, depending on the time of birth, during the first year of life or until the experienced 2nd early summer.

Proposed maximum level for the addition of vitamin D to food supplements (per daily dose of an individual product):

Those who otherwise want to supplement vitamin D can resort to food supplements with up to 20 micrograms of vitamin D per daily dose. This applies to adolescents and adults. With this amount, the daily requirement is covered, while health impairments are not expected. High dosages should only be taken under medical supervision.

7/11/2023

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