Vitamin D is one of the most important vitamins for humankind and %95 of its requirements are acquired by synthesising solar rays on skin. While lack of vitamin D can lead to many diseases, especially cancer, the ones who get vitamin D in an appropriate level, can reduce this risk if they exercise. If, also, vitamin D level is high, obesity risk will be minimized because of eating less thanks to leptin hormone. Vitamin D receptors exist in approximately 40 tissues. The most imporant effect of vitamin D, which dissolves in fat, is on bone mineralization phosphorus metobolism and calcium. People whose vitamin D level is low, should take nourishment by sources rich in vitamin D instead of helper pills.