Vitamin D is a fat-soluble vitamin that is essential for optimal health. Only a handful of foods contain significant amounts of this vitamin. These include fatty fish, organ meats, certain mushrooms and fortified foods.
However, unlike other vitamins that you can only get through your diet, vitamin D can also be made by your body when your skin is exposed to the sun. For this reason, vitamin D is technically considered a hormone. The limited availability of vitamin D in the human diet, combined with most people’s insufficient sun exposure, may explain why up to 41.6% of the US population has deficient blood levels.
Interestingly, having adequate blood levels of this vitamin can provide many important health benefits. This article lists 15 science-based benefits linked to vitamin D.