Together with calcium and vitamin K, vitamin D keeps our bones and teeth strong and stable, protects against sun allergies in summer and against influenza death in winter. If there is no vitamin D, calcium cannot be absorbed from the intestines, which can lead to all the problems associated with a calcium deficiency.
This includes not only long-term bone and tooth problems, but also musculoskeletal problems – starting with the vascular muscles, which can lead to circulatory problems, dizziness and permanent headaches, neck pain, back pain, whole body pain and even heart failure if the heart muscle is affected.
Even heartburn can occur as a result of vitamin D deficiency, when the smooth muscles of the digestive system suffer from calcium deficiency and no longer function properly. Vitamin D deficiency is now associated with many other health problems, including autoimmune diseases such as multiple sclerosis.
Fortunately, our bodies produce vitamin D on their own – with the help of the sun’s rays in the skin. But it only does this when the skin actually sees sunlight at regular intervals.
Since many people in industrial nations unnaturally do not spend most of their daily sunshine hours outdoors, but in the office, at university, at school, in the workshop, etc., millions of people suffer from a considerable vitamin D deficiency.
The situation gets even worse in winter, especially in the temperate zone. There the sun does not even reach the strength to stimulate the formation of vitamin D in our skin in the low-light months – even if it shines.
So in winter we have to feed on our vitamin D reserves from summer and hope that they will suffice. However, since our body’s vitamin D storage capacity is usually overtaxed by the usual long winters and our vitamin D reserves usually run out after only three to four months, a winter without vitamin D supplements is hardly conceivable for the typical inhabitant of the industrial nations.