The 'Sunshine Vitamin' is generally acquired by the body in two ways - exposure to the sun's ultraviolet (UV) rays and dietary intake. Nature's Sunshine's Vitamin D3 is a fat-soluble vitamin. Vitamin D is best known for its role in preventing rickets and maintaining proper levels of calcium in the blood.
It is generally thought that if you get enough time in the sun and eat a diet with foods rich in Vitamin D, deficiency will not be a problem. However, many other factors tend to come into play when it comes to receiving UV exposure of your body to the sun and then processing that into vitamin D in the body. Things like time spent in the sun, personal genetics, age, use of sunscreens which block UV rays, and even where you live can all have an effect.