Vitamin D is a fat-soluble vitamin best known for its roles in preventing rickets and maintaining proper levels of calcium in the blood. The 'Sunshine Vitamin' is generally acquired by the body in two ways - exposure to the sun's ultraviolet (UV) rays and dietary intake.
Vitamin D supplementation helps to prevent Vitamin D deficiency which is important as the vitamin is a factor in the maintenance of good health. Furthermore Vitamin D helps in the development and maintenance of bones and teeth, and the absorption and use of calcium and phosphorus.
It has generally been thought that if you get enough time in the sun and eat a diet with foods like Vitamin D fortified milk, deficiency will not be a problem. However, many factors come into play when it comes to your body receiving UV exposure to the sun and processing that into vitamin D in the body. Things like time spent in the sun, age, genetics, use of UV-blocking sunscreens, and even where you live can all have an effect.