Vitamin D and sunshine are necessary for both your health and public health in general, and your body produces the vitamin itself when you get enough sun. Because vitamin D helps you absorb calcium, it is essential for maintaining healthy bones and strengthening your skeleton. It also boosts your immune system, and a deficiency in vitamin D is linked to over 100 diseases. Supplementation of vitamin D through food or supplements can help. However, the best way to ensure your body is producing enough vitamin D is to get 10 to 30 minutes of midday sunlight, several times a week.