Vitamin D was discovered in 1922 in fish oil. It was later discovered that vitamin D is also produced in the human body under the influence of ultraviolet light.

Vitamin D is important for normal bone growth, teeth, muscle function and the immune system. It is soluble in fat and comes in nature in two forms. We distinguish between vitamin D2 (ergocalciferol), which is of plant origin, and D3 (cholecalciferol), which is found in animal products such as eggs, liver, fatty fish, and milk and dairy products.Vitamin D3 can also be formed in the skin under the influence of UVB rays in sunlight. Therefore, vitamin D has a special place among vitamins.

The human body can provide a certain amount of vitamin D2 or D3 from dietary sources, but it also has all the necessary enzymes for its own synthesis of vitamin D3. In the presence of UVB light, keratinocytes in the skin can synthesise it from the body’s own 7-dehydrocholesterol.

The amount of vitamin produced depends on the skin colour of the individual, the time of day and year when the individual is exposed to the sun, and the latitude. A sufficient amount of vitamin D, which the body needs, is formed if the skin of the face and hands are exposed to sunlight for 5-10 minutes a day. It is important that we are directly exposed to sunlight and that we do not use sunscreen. After a few minutes of sunbathing, of course, use a protective cream and move to the shade.

With normal exposure to sunlight, 20-50 micrograms of vitamin D are synthesised in the skin daily. Sunscreen cannot exceed adequate amounts of vitamin D, as the body produces only as much as it needs. According to the recommendations of the European Food Safety Authority (EFSA), adults need 20 micrograms per day, which is equivalent to 800 international units (IU).

People who spend most of their time indoors or living in northern latitudes can only get enough vitamin D through dietary supplements, as they cannot get enough of it even with a balanced diet. The problem of sufficient intake occurs mainly in winter, as we are less exposed to sunlight than in summer.