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.
ISRN Endocrinol. 2013;2013:348705. doi: 10.1155/2013/348705. Epub 2013 Mar 14.
Jorde R, Strand Hutchinson M, Kjærgaard M, Sneve M, Grimnes G.
Tromsø Endocrine Research Group, Department of Clinical Medicine, University of Tromsø, 9037 Tromsø, Norway ; Division of Internal Medicine, University Hospital of North Norway, 9038 Tromsø, Norway.
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 (HbA1c), 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 HbA1c 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 (P < 0.05).
No serious side-effects were seen. In conclusion, in subjects without vitamin D deficiency, there is no improvement in serum lipids, HbA1c, or HS-CRP with high dose vitamin D supplementation. If anything, the effect is negative.
PMID: 23577264
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Note: only a small change in risk markers for diease, no actual relationship of vitamin D to actual disease