We need vitamin D above all for healthy bones. Supposedly it should also help against various other diseases. That’s what science says.
What is Vitamin D
When we talk about vitamin D, we don’t mean a specific substance or vitamin. Scientists use the term as a generic term for a group of fat-soluble vitamins – the so-called calciferol. The most important forms include vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol).The human body can only produce vitamin D under the influence of light, i.e., UV-B radiation. That is why vitamin D is often referred to in advertising as “the sun hormone.”
Why is Vitamin D Important for the Body?
We need it, especially for our bones. Because thanks to vitamin D, our body can absorb calcium from food. That hardens bones and teeth, for example. It also influences muscle strength and is important for metabolic processes. Deficiency in adults can cause bones to deform, cause pain, and muscle loss. A deficiency also increases the risk of developing osteoporosis – a weakening of the bones. Deficiency in infants and children is at risk of rickets, a serious disorder of bone growth that can lead to permanent deformation of the skeleton.
Why Does the Vitamin D Balance Fluctuate?
Since our vitamin D content in the body depends on the season, among other things, it can fluctuate. Sometimes it is low, sometimes it is higher. The body produces more vitamin D, especially in the warm summer months, as the sun shines a lot, and we are therefore exposed to a lot of UV-B radiation. Our vitamin D supply is estimated to be 80 to 90 percent via the endogenous synthesis in the skin – if we are regularly in the fresh air with enough bare skin. However, in the winter months, things look a little different: Our body can only produce a very limited amount of vitamin D.
The UV-B rays required for self-synthesis only reach regions below the 35th parallel all year round. At higher latitudes, the intensity and duration of sufficient radiation decrease, and the formation of vitamin D depends on the season.
The Body Stores Vitamin D
The body stores the vitamin D formed in summer in adipose tissue and skeletal muscles, which helps maintain the vitamin D serum concentration in winter. A study from Sweden showed that we have low vitamin D levels more frequently in the winter months. For this purpose, the blood of 540 test subjects was examined. In addition, they had to provide regular information about their smoking behavior, physical activities, and possible vitamin D supplements.
The result: the vitamin D level was on average lower in the winter months than in the summer months. Around 50 percent of the test subjects: half of the year, the concentration was below 50 nanomoles per liter. In the summer months, the concentration for this was over 80 percent of the test persons: inside at over 50 nanomoles per liter, in 41 percent of these people even over 75 nanomoles per liter.
