Vitamin D is in short supply in the Nordic countries
Vitamin D is produced in the skin by exposure to sunlight during the spring and summer months in Sweden. Between May and September, absorption through the skin is at its best, provided you are not wearing sunscreen or full-coverage clothing. During the summer months, the sun is the primary source of vitamin D, but from late autumn until spring, there is not really any significant synthesis in the body, as UV-B radiation is filtered out in the atmosphere when the sun is low. Until just a few years ago, many people assumed that the synthesised amount of vitamin D produced in the body during the summer should cover the need even during the winter months, because vitamin D is fat-soluble and can therefore be stored in the body. However, it is now known that the amount synthesised is often not sufficient and that only some people have produced the amount needed to cover a larger part of the requirement even during the winter months. Many people are therefore at risk of having too low levels of vitamin D for much of the year.
Sunscreen protects - but also blocks vitamin D synthesis
The use of sunscreens has an important role to play in protecting the skin from the harmful effects of the sun's rays. At the same time, it also blocks the process by which the sun's rays synthesise and create our natural stores of vitamin D in the skin. The colour of your skin also plays a role in how effectively it is absorbed. The darker your skin colour, the less vitamin D is absorbed. Northerners with very fair skin like to put on a little extra oil to avoid the risk of redness and burning, which is absolutely right, but then we also miss out on the vitamin D. Instead, many choose to protect themselves with full-coverage clothing or lie in the shade, which also means we miss out on vitamin D from the sun.
Vitamin D in the diet
Unfortunately, vitamin D is not found in large amounts in the diet, and especially not in vegan foods. Therefore, some dairy products are fortified with vitamin D, including plant-based alternatives, as a way to boost levels in foods we eat frequently. Oily fish, eggs and meat are examples of foods that contain vitamin D but in vegetables there are really only small amounts in some mushrooms and the form of vitamin D found in chanterelles, for example, is in a less active form. Vegans therefore belong to a group that needs to watch their vitamin D intake a little extra.
Affects important systems in the body
Vitamin D has the ability to influence the functions of many of the body's cells, which in turn affect our health in a number of ways. Vitamin D plays an important role in the absorption and utilisation of calcium and phosphorus, in the normal functioning of the nervous system and muscles, and it also contributes to the normal functioning of the immune system. Other parts of the body also depend on vitamin D, such as the bones and teeth, and it is needed for the cell division process.
