The impact of low vitamin D status on asthma development is unclear. The authors investigated the relation between the baseline serum 25-hydroxyvitamin D (25(OH)D) level and incident asthma in adults, including possible effect modification by allergy status, using allergic rhinitis as a proxy measure. A cohort of 25,616 Norwegian adults aged 19-55 years participated in 2 surveys of the Nord-Trø...

Observational studies suggest an adverse effect of maternal hypovitaminosis D during pregnancy. However, intervention studies failed to show convincing benefit from vitamin D supplementation during pregnancy. With analytical advances, vitamin D can now be measured in ten forms-including as epimers-which were thought to be biologically inactive, but can critically impair immunoassays. The aim of...

Vitamin D is a “hot topic,” with the number of citations in PubMed exceeding 2400 in 2009, a 3-fold increase in 1 year. In the US, the number of requested 25-hydroxyvitamin D (25-OHD) assays is increasing exponentially. Not all of the published material has validity, however. A panel of experts was invited to address a series of questions pertaining to laboratory methods and clinical applicatio...

BACKGROUND To our knowledge, no studies have reported on the long-term variability of vitamin D status in adolescents. OBJECTIVE To determine whether tracking of vitamin D status occurs in healthy adolescents, we assessed the variability of 25-hydroxyvitamin D [25(OH)D] every 2 y over a 10-y period in a longitudinal cohort of adolescents living in Johannesburg, South Africa (latitude 26°S). ...

This report describes studies of 25-hydroxyvitamin D3 (25OHD3) kinetics in 10 yearling crossbred wethers (40 to 52 kg body weight) administered [3H] 25-hydroxyvitamin D3 [( 3H] 250HD3). The wethers were divided into two groups of five before dosing with the labeled compound: Group 1 wethers were exposed 2 h daily for 8 to 10 wk to ultraviolet radiation from fluorescent sunlamps. Plasma 250HD3 i...

There has been an increased interest in the role of vitamin D in depression; however, there have been few studies conducted in younger population groups. Our aim was to investigate the association between vitamin D status and depressive symptoms in a non-clinical young adult sample living in Dunedin, New Zealand. A cross-sectional sample of 615 young adults completed a questionnaire including d...

Background: To our knowledge, no studies have reported on the long-term variability of vitamin D status in adolescents. Objective: To determine whether tracking of vitamin D status occurs in healthy adolescents, we assessed the variability of 25-hydroxyvitamin D [25(OH)D] every 2 y over a 10-y period in a longitudinal cohort of adolescents living in Johannesburg, South Africa (latitude 268S). D...

Evidence supporting the UVB/vitamin D/cancer theory continues to mount with little detraction, although there are some inconsistent results, such as some from Nordic countries, with respect to serum calcidiol levels. Also, studies designed and conducted before it was realized that dietary sources are largely inadequate to have a pronounced effect on cancer risk were largely unable to confirm a ...

The effects of dietary supplementation with phytase and 25-hydroxycholecalciferol on the performance characteristics of commercial layers that were inoculated prelay (12 wk of age) or at the onset of lay (22 wk of age) with F-strain Mycoplasma gallisepticum were assessed. Experimental layer diets, which included a basal control diet or the same diet supplemented with 0.025% phytase and 25-hydro...

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 ...