No significant effect on bone mineral density by high doses of vitamin D3 given to overweight subjects for one year
1 Institute of Clinical Medicine, University of Tromsø, and Medical Clinic, University Hospital of North Norway, Tromsø, Norway
2 Department of Ophthalmology and Neurosurgery, Division of Ophthalmology, University Hospital of North Norway, Tromsø, Norway
3 Hormone Laboratory, Aker University Hospital, Oslo, Norway
4 Department of Medical Biochemistry, University Hospital of North Norway, and Institute of Medical Biology, University of Tromsø, Tromsø, Norway
5 Center for Atherothrombotic Research in Tromsø (CART), Institute of Clinical Medicine, University of Tromsø, Norway
Nutrition Journal 2010, 9:1 doi:10.1186/1475-2891-9-1Published: 7 January 2010
In meta-analyses supplementation with vitamin D appears to reduce incidence of fractures, and in cross-sectional studies there is a positive association between serum 25-hydroxyvitamin D (25(OH)D) levels and bone mineral density (BMD). However, the effect of supplementation with high doses of vitamin D on BMD is more uncertain and could in theory have both positive and negative effects.
The study was a one year, double blind placebo-controlled intervention trial performed at the University Hospital of North Norway. 421 subjects, 21 - 70 years old, were included and 312 completed the study. The subjects were randomized to vitamin D3 40.000 IU per week (DD group), vitamin D3 20.000 IU per week (DP group), or placebo (PP group). All subjects were given 500 mg calcium daily. Serum 25(OH)D, osteoprotegrin (OPG), receptoractivator of nuclear factor-kappaB ligand (RANKL), and BMD at the lumbar spine and the hip were measured before and at the end of the study.
At baseline the mean serum 25(OH)D levels were 58 nmol/L (all subjects) and increased to 141 and 100 nmol/L in the DD and DP groups, respectively. After one year, no significant differences were found between the three groups regarding change in BMD, serum OPG or RANKL.
Supplementation with high doses of vitamin D for one year does not appear to have a negative effect on BMD in healthy subjects. In order to disclose a positive effect, subjects with low BMD and/or low serum 25(OH)D levels need to be studied.
The trial was registered at ClinicalTrials.gov (NCT00243256).