Vitamin D in public health nutrition.

Serum 25-hydroxyvitamin D concentration (25(OH)D) is considered the best marker of vitamin D status, with low concentrations indicating low status. However, cut-points for vitamin D deficiency and insufficiency vary, reflecting variable views among experts. Notably, the Institute of Medicine concluded in 2010 that there are no systematic reviews on the cut-points, and this still stands. Papers by Chang et al. and Lee et al. used a cut-off of vitamin D, 50nmol/l to represent deficiency, reflective of the cut-offs recommended by the Institute of Medicine, the Endocrine Society and the Nordic Nutrition Recommendations. The paper by Oliveira et al. used a cut-off of #25nmol/l to assess deficiency whereas Wallingford et al. and Golbahar et al. reported vitamin D deficiency as serum 25(OH)D,30nmol/l (risk for bone health) in line with the Institute of Medicine recommendations. Other papers separated vitamin D status into quartiles and tertiles, which may be valid for their research but hinders overall assessment of vitamin D status against established cut-offs.