Vitamin D is a fat-soluble vitamin in a family of compounds that includes vitamins D1, D2, and D3.
Your body produces vitamin D naturally when it’s directly exposed to sunlight. You can also get vitamin D from certain foods and supplements to ensure adequate levels of the vitamin in your blood.
Vitamin D has several important functions. Perhaps the most vital are regulating the absorption of calcium and phosphorus and facilitating normal immune system function (1Trusted Source).
Getting enough vitamin D is important for typical growth and development of bones and teeth, as well as improved resistance to certain diseases.
Here is more information about the benefits of vitamin D, plus information about downsides, how much you need, and foods with vitamin D.