Update on vitamin D

Vitamin D deficiency and insufficiency defined by a 25-hydroxyvitamin D (25OHD) serum level < 20 ng/mL and between 20 and 30 ng/mL respectively, are two highly frequent conditions that are associated with an increased risk of developing several pathologies, not only of the skeleton. While decreasing the risk of fractures and falls with vitamin D supplementation is well documented by intervention studies, the other potential effects of vitamin D are mostly documented by observational and experimental studies. Even if a consensus on the optimal requirement does not exist, all experts agree on the fact that the current recommended dietary intakes (200 IU/day in France) are extremely insufficient and must be increased. The present review describes the metabolism and effects of vitamin D, discusses the way the definitions of vitamin D deficiency/insufficiency are established, as well as the patients in whom 25OHD should be measured. Finally, it proposes different protocols to supplement/treat with vitamin D. (C) 2013 Published by Elsevier Masson SAS on behalf of Societe francaise de nutrition.