Especially in spring, a bit of sun is not only good for your well-being, but also for your bones! Humans are able to produce vitamin D in the skin themselves under the influence of UV-B rays. This vitamin regulates the metabolism of calcium and phosphate and promotes the development and maintenance of bones.
Even a minimal supply of UV-B radiation boosts the body's own production of vitamin D.
Depending on the skin type, time of day and region in which a person lives, according to the World Health Organization, 5 to 15 minutes of solar radiation on the face, hands and arms are enough three times a week during the summer months to produce enough vitamin D. The production reaches its maximum after about 20 minutes and can not be further increased by extensive sunbathing!
The clearer the air and the greater the proximity to the equator, the stronger the UV radiation and even an even shorter exposure to the sun is sufficient. When the sky is cloudy, the UV radiation is slightly lower. With a longer stay outdoors, you can boost your vitamin D production. Some high-fat foods such as herring, mackerel, salmon, tuna, liver, chicken egg and margarine (enriched with vitamin D) as well as mushrooms contribute to vitamin D supply.
On the one hand, a minimal supply of sunlight is important for vitamin D formation, on the other hand, UV light is a major risk factor for skin cancer. With a visit to the sunbed, which secretes predominantly UV-A rays instead of the necessary UV-B rays, you can not improve your vitamin D supply. Staying outdoors alone promotes the formation of vitamin D and strengthens the bones, preferably in conjunction with lots of exercise.
However, there are groups of people where self-production is not always sufficient and the supply of vitamin D can be critical. Affected are infants or people who are rarely outdoors, and the elderly. In children, an adequate supply of vitamin D is important, as constantly new bone mass must be formed. In the case of child malnutrition rickets can occur: the bones remain soft and deform. Infants therefore receive vitamin D tablets as prophylaxis.
In adulthood, severe vitamin D deficiency can lead to osteomalacia, which increases the risk of spontaneous fractures. Inadequate vitamin D supplementation contributes to the development of osteoporosis in old age. Especially older people should therefore take care that their body gets enough vitamin D, so that the bones remain stable. Because with age, the ability of the skin to produce vitamin D itself decreases. Also, many older people rarely spend time outdoors.
In the winter months, the radiation of the sun is not sufficient to form corresponding vitamin D levels. Therefore, special emphasis is placed on regular walks and nutrition.
The DGE recommends a daily intake of 5 μg of dietary vitamin D, and it should be 10 μg in the elderly over 65 years of age. An amount of 5 μg of vitamin D is contained in 250 g of mushrooms, for example. An important source of vitamin D is also fish: 100 g of tuna provide 5 μg, 100 g of herring even 23 μg of the essential vitamin.