Table of Contents
ISRN Endocrinology
Volume 2013 (2013), Article ID 348705, 7 pages
http://dx.doi.org/10.1155/2013/348705
Clinical Study

Supplementation with High Doses of Vitamin D to Subjects without Vitamin D Deficiency May Have Negative Effects: Pooled Data from Four Intervention Trials in Tromsø

1Tromsø Endocrine Research Group, Department of Clinical Medicine, University of Tromsø, 9037 Tromsø, Norway
2Division of Internal Medicine, University Hospital of North Norway, 9038 Tromsø, Norway
3Division of Surgery and Clinical Neuroscience, Department of Ophthalmology, Oslo University Hospital, 0424 Oslo, Norway

Received 24 January 2013; Accepted 23 February 2013

Academic Editors: C. Bizzarri, O. Giampietro, A. Saxe, and J. Schiettecatte

Copyright © 2013 Rolf Jorde et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Data were pooled from four randomized clinical trials with vitamin D performed in Tromsø with weight reduction, insulin sensitivity, bone density, and depression scores as endpoints. Serum lipids, glycated hemoglobin ( ), and high sensitivity C-Reactive Protein, (HS-CRP) were measured at baseline and after 6–12 months of supplementation with vitamin D 20 000 IU–40 000 IU per week versus placebo. A total of 928 subjects who completed the interventions were included. At baseline the mean serum 25-hydroxyvitamin D (25(OH)D) level in those given vitamin D was 55.9 (20.9) nmol/L and the mean increase was 82.4 (40.1) nmol/L. Compared with the placebo group there was in the vitamin D group at the end of the studies a slight, but significant, increase in of 0.04%, an increase in HS-CRP of 0.07 mg/L in those with serum 25(OH)D < 50 nmol/L, and in those with low baseline HDL-C and serum 25(OH)D < 50 nmol/L a slight decrease serum HDL-C of 0.08 mmol/L ( ). No serious side-effects were seen. In conclusion, in subjects without vitamin D deficiency, there is no improvement in serum lipids, , or HS-CRP with high dose vitamin D supplementation. If anything, the effect is negative.