DUNDEE, SCOTLAND — A small, randomized trial of high-dose vitamin D has failed to show a benefit of the supplement in reducing blood pressure or improving vascular health in older patients with isolated systolic hypertension (ISH).
Results of the Vitamin D in ISH (VitDISH) trial, led by Dr Miles D Witham (University of Dundee, Scotland) were published online yesterday in JAMA Internal Medicine.
Authors of the study, which randomized 159 patients to either 100 000 U cholecalciferol every three months for one year or to placebo, note that vitamin-D supplementation had never been studied in the setting of ISH, despite this being the most common form of hypertension in the elderly. In VitDISH, subjects' mean 25-hydroxyvitamin-D levels were low at baseline and increased significantly over the 12 months. Yet these increases did not translate into meaningful changes in mean office blood pressure, 24-hour blood pressure, arterial stiffness, endothelial function, cholesterol or glucose levels, or walking distance.
It's possible that "vitamin D may have no significant effect on blood pressure" at all or in this specific group of patients, the authors muse. Another possibility is that some subjects enrolled in VitDISH merely had white-coat hypertension, diluting the impact of vitamin D.
"Our results do not lend support to performing large randomized controlled trials aimed specifically at blood-pressure reduction, at least in this patient group," Miles et al conclude. The door remains open, however, for vitamin D to improve other aspects of cardiovascular health "via non–blood-pressure effects," they concede.
An accompanying commentary by Dr Edward Giovannucci (Harvard University, Boston, MA) zeroes in on the potentially complementary role of calcium, noting that it is populations that also have very low calcium intakes that might show the most benefit from vitamin D (a point also noted by Miles et al).
That said, Giovannucci concludes, "considering all the evidence, it does not appear likely that vitamin-D supplementation will have a strong influence on blood pressure across all populations."
Heartwire from Medscape © 2013 Medscape, LLC
Cite this: Vitamin D No Help in Isolated Systolic Hypertension: VitDISH - Medscape - Aug 14, 2013.