Tiny increase in H1C if supplement and already have enough vitamin D

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

ISRN Endocrinology, Volume 2013, Article ID 348705, 7 pages

Rolf Jorde,1,2 Moira Strand Hutchinson,1 Marie Kjaergaard,1,2 Monica Sneve,3 and Guri Grimnes 1,2

1 Troms0 Endocrine Research Group, Department of Clinical Medicine, University of Troms0, 9037 Troms0, Norway

2 Division of Internal Medicine, University Hospital of North Norway, 9038 Troms0, Norway

3 Division of Surgery and Clinical Neuroscience, Department of Ophthalmology, Oslo University Hospital, 0424 Oslo, Norway

Correspondence should be addressed to Rolf Jorde; rolf.jorde@unn.no

Received 24 January 2013; Accepted 23 February 2013

Data were pooled from four randomized clinical trials with vitamin D performed in Troms0 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 000IU-40 000IU 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.

PDF is attached at the bottom of this page

The title screams that there could be a negative effect from taking vitamin D

The data does indeed show a negative effect of 0.04%

Glycated_hemoglobin Wikipedia

This serves as a marker for average blood glucose levels over the previous months prior to the measurement.