Long-Term High-Dose Vitamin D3 Supplementation and Blood Pressure in Healthy Adults - A Randomized Controlled Trial
Robert Scragg, Sandy Slow, Alistair W. Stewart, Lance C. Jennings, Stephen T. Chambers, Patricia C. Priest, Christopher M. Florkowski, Carlos A. Camargo Jr, David R. Murdoch
From the School of Population Health, University of Auckland, Auckland, New Zealand (R.S., A.W.S.); Department of Pathology, University of Otago, Christchurch, New Zealand (S.S., L.C.J., S.T.C., C.M.F., D.R.M.); Preventive and Social Medicine, University of Otago, Dunedin, New Zealand (P.C.P.); and Department of Emergency Medicine, Massachusetts General Hospital, Harvard Medical School, Boston (C.A.C.).
Correspondence to Robert Scragg, Section of Epidemiology and Biostatistics, School of Population Health, University of Auckland, Private Bag 92019, 261 Morrin Rd, Glen Innes, Auckland, New Zealand. E-mail r.scragg at auckland.ac.nz
Previous randomized controlled trials of vitamin D supplementation and blood pressure (BP) mainly have given vitamin D for short periods (<6 months) or at low doses (400 IU per day). This study aims to determine whether long-term high-dose vitamin D taken for 18 months lowers BP. Adults were recruited from a healthcare organization or university into a double-blind controlled trial and randomized to receive either vitamin D3 200 000 IU for 2 months followed by 100 000 IU monthly up to 18 months (n=161) or placebo (n=161). BP was measured at baseline, 5, and 18 months. Subjects had a mean (SD) age of 47.6 (9.7) years, 75% were women, and 94% were of European ancestry (white).
Mean (SD) 25-hydroxyvitamin D3 changed from 73 (22) nmol/L at baseline to 124 (28) nmol/L at 18 months in the vitamin D group, and from 71 (22) nmol/L to 56 (22) nmol/L in the placebo group. Mean BP was similar for the vitamin D and placebo groups at baseline (123.4/76.3 versus 122.6/75.6 mm Hg; respectively).
The mean change (95% confidence interval) in BP at 18 months minus baseline in the vitamin D group compared with placebo group was
- −0.6 (−2.8 to 1.6) mm Hg for systolic (P=0.61) and
- 0.5 (−1.1, 2.2) mm Hg for diastolic (P=0.53).
Long-term vitamin D supplementation, which increased mean 25-hydroxyvitamin D3 concentration >100 nmol/L for 18 months, had no effect on systolic or diastolic BP in predominantly white, healthy adults without severe vitamin D deficiency. Beneficial effects on BP cannot be ruled out for other populations.
4 other RCT have found a change in hypertension with vitamin D