Man makes vitamin D from sunlight on the skin. Vitamin D will therefore often referred to as a sun vitamin. If you spend much time outdoors, can cover around 80% of the vitamin D needs this endogenous synthesis. The rest has to be supplied with food.

The fat-soluble vitamin D allows the absorption of calcium and phosphorus and is important for the strength of bones and teeth. The muscle function and the immune system benefit from vitamin D. The sun vitamin is mainly found in animal products such as herring, beef liver, cheese or eggs. In particular, vegetarians and vegans are therefore dependent on alternative sources of vitamin D during the dark season.