Vitamin D is both a nutrient we eat and a hormone our bodies make. It is a fat-soluble vitamin that has long been known to help the body absorb and retain calcium and phosphorus; both are critical for building bone. Also, laboratory studies show that vitamin D can reduce cancer cell growth, help control infections and reduce inflammation. Many of the body’s organs and tissues have receptors for vitamin D, which suggest important roles beyond bone health, and scientists are actively investigating other possible functions.
The main function of Vitamin D3 is to help calcium and phosphorus to be absorbed, and these are our healthy bones, muscles, heart, vision, skin, hair, teeth and nails. That is, if you don't get Vitamin D3, your body will be worse at absorbing these minerals. The quality of the additive is high, the size of the capsules is average.