A vitamin D3 deficiency is one of the most common deficiency symptoms that occur in Germany. The body can produce the fat-soluble vitamin itself if enough sunlight falls on the skin. The body can increase its own production of vitamin D3 through the UV rays in sunlight. Many people stay in dark rooms during the day or cannot absorb enough sunlight in the winter months to cover their vitamin D3 requirements in the long term. In this blog post you will learn how to detect and correct a vitamin D3 deficiency.