Vitamin D, also called calciferol, is crucial for the normal development and balance of the body. The synthesis precursors of this vitamin can be found in foods of animal and vegetal origin: fish liver oil, chicken liver, egg yolks and industrially enriched food (eg.: margarines, cereals, etc.). However, these precursors require exposure to ultraviolet radiation in the body, to be converted to its active form and perform its activity. Hence, exposure to the sun, is a determining factor for the synthesis of the active form of vitamin D. Combining the consumption of calcium with vitamin D and some exercises that involve impact (eg.: walking, running, lifting dumbbells) helps to get this mineral to the bone structure and teeth, where it is most needed. At the same time, the consumption of vitamin D helps strengthen the immune system.