Vitamin D is vital for us humans. But unlike the other vitamins, our organism can produce this substance itself – with the help of sunlight. Are moderate sunbaths healthy after all?
Vitamin D is the only vitamin that the body can produce itself. However, this only works if the skin is exposed to sunlight. A photochemical reaction in the skin causes the required substance to form. This, however, requires UV radiation – that is, the exact wavelength of light that can also cause damage to the skin: painful sunburn and possible changes in the genetic material of the skin cells, which can lead to cancer.
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Do not demonize the sun
Dermatologists therefore rightly warn against the dangers of solar radiation. At the same time, however, there are voices that advise against completely demonising exposure to sunlight. This category includes a highly regarded Swedish study published in March 2016 in the Journal of Internal Medicine, a renowned medical journal. Researchers from the Karolinska University Hospital in Stockholm investigated how frequent sunbathing affects life expectancy. The researchers analysed the data of around 30,000 Swedish women who were observed in a long-term study over a period of 20 years.
To the astonishment of many, it turned out that women who regularly enjoyed the sun had a higher average life expectancy than women who avoided it. In particular, cardiovascular diseases were much rarer. However – and this should not go unmentioned – there were also more cases of skin cancer among sun worshippers despite a longer life expectancy.
However, sunlight also seems to have a positive effect on health. The Swedish scientists were unable to provide a clear explanation of how this works. But it has been suspected for some time that vitamin D, the substance that the body forms under the influence of sunlight, plays an important role. Because vitamin D is necessary for numerous metabolic processes in the body. It not only regulates the formation and breakdown of bones, which is why rickets and osteoporosis are typical symptoms of vitamin D deficiency. Vitamin D also seems to be important for body defence and the immune system. Various studies suggest that there is a link between vitamin D deficiency and influenza waves, cardiovascular problems and even cancer. However, research is still in its infancy – and some results are contradictory. An oversupply of vitamin D could also have negative effects, which is why many doctors are rather critical of the long-term intake of vitamin D supplements.
Even slight undersupply problematic
Nevertheless, even a slight undersupply can be problematic. And this is more often the case in our latitudes during the winter months than many people are aware of. Pronounced deficiency symptoms, especially rickets, are very rare in industrialised countries, as they are mainly associated with malnutrition. Nevertheless, a study conducted by the University of Boston was able to show that rickets are very rare: At the end of winter, even in highly developed countries, many people – especially children – have significantly lower vitamin D concentrations in their blood. This probably increases the risk of disease – from infections and high blood pressure to autoimmune diseases.
Especially in spring it makes sense to stimulate the body’s own vitamin production – and to use the sunlight accordingly. This doesn’t even require a lot of sunbathing. Nobody has to expose themselves to the sun for hours and hours and risk sunburn to get their vitamin balance in order. Even in our latitudes, a short stay of a few minutes a day in daylight is enough. Those who want to stay longer in the sun, be it for sports or sunbathing, should definitely pay attention to sun protection with an adequate sun protection factor.
By the way: The skin colour has a significant influence on how effectively the organism can produce vitamin D with the help of sunlight. The brighter the skin, the less light is needed – and vice versa. It is therefore assumed that the particularly bright complexion of northern Europeans is an evolutionary response to the winter lack of light in those countries. In the vicinity of the tropics, where sunshine is intense all year round, the skin of humans is particularly strongly pigmented. This keeps as much UV radiation as possible away from the more sensitive deep skin layers. In total, the people there get plenty of sunlight, so that for this reason in Africa, South Asia, Latin America, etc. no vitamin D deficiency is to be feared.