Vitamin D, also known as “sunshine vitamin” is a group of fat-soluble compounds. The most important ones for human bodies are vitamin D2 and vitamin D3. D2 naturally is present in plants, while D3 is synthesized by our organisms when we are exposed to sun rays. Actually, vitamin D should be seen more as a hormone than a vitamin. It is synthesized in our skin, but it is actually activated in a different place in our bodies – liver and kidneys.