Vitamin D, how many? From function to population

Introduction and Objective Vitamin D (VitD) is obtained from food (ergocalciferol and cholecalciferol) and synthesized in the skin after exposure to UV radiation from sunlight (cholecalciferol). The best known functions of VitD are to promote the elevation of serum calcium and phosphate and to enhance the effects of parathormone (PTH). Although it is also described its pleiotropic role, which widely spreads from osteoclastic differentiation to cardiovascular and cancer development protection. Family doctors (FD) and patients are blasted with information about VitD benefits, its optimal plasma concentrations upper 30ng/mL and the need to prescribe it. However this target involves financial effort and could not have the announced result. We aim to review the evidence of VitD supplementation in general population. Methods Bibliographic search, PubMed (1990-2016), English and Portuguese, using MeSH terms vitamin D, femoral fractures and dietary supplements. Manual review of search results identified trials about VitD supplements usage. Result and Conclusion The VitD ideal concentration is calculated mainly based on its concentration capable to promote the PTH increases. This “ideal” target 30 ng/mL involves 52-77% of population and there is a lack of evidence to support a higher target than 20ng/ml. Moreover, the use of VitD supplement for preventing fractures (elderly in the community) showed no benefit (100%), 2.8% chance to develop kidney injury, and seems to be linked to an increased risk of falls. There is a lack of evidence to support all the present pressure for VitD supplement. Towards the pharmaceutical industry and “pop-ups” publicity, FD needs to make difference between evidence and “disease mongering”.