BACKGROUND & AIMS: Vitamin D is a fat-soluble vitamin whose main function in the body is the regulation of bone mineral metabolism. In the last two decades, there has been an intensive research for possible vitamin D benefits in non-skeletal health but as today it still remains unclear. The aim of this article is to review vitamin D metabolism and the natural sources to encourage lifestyle changes to avoid deficiency. REVIEW: Universal screening for vitamin D deficiency is not warranted and it should only be done in cases with risk factors for vitamin deficiency. Vitamin D is measured in the body by determining 25-hydroxycholecalciferol; values below 20 ng/mL (50 nmol/L) are considered inadequate. The three sources of vitamin D are the ultraviolet sun radiation, diet and supplementation. The role of vitamin D supplementation out of the osteoporosis treatment and prevention still remain controversial. Healthy sun exposure and diet should be discussed with all patients with vitamin D deficiency and in general population in promoting health. The skin, through solar radiation, is the main source of vitamin D and provides 90% of the body's needs. CONCLUSIONS: Changing lifestyle habits, encouraging a controlled sun exposure and proper vitamin D diet is a preventive strategy that should be applied in our daily practice to prevent osteoporosis and other diseases associated with low vitamin D.