Original Article

Effects of Vitamin D Supplementation on Blood Pressure

Authors: Sheng Hui Wu, MD, MMed, PhD, Suzanne C. Ho, MD, FRCP, FRACP, FFPH, Liu Zhong, MD, MMed

Abstract

Objective: Inconsistent findings from epidemiological studies have continued the controversy over the role of oral vitamin D supplementation in reducing blood pressure in normotensive or hypertensive populations.


Methods: We performed a literature search up to December 2009, with no restrictions. Only double-blind randomized controlled trials (RCTs) of oral vitamin D supplementation in normotensive or hypertensive individuals with blood pressure measurements were included.


Results: From 244 retrieved papers, four RCTs involving 429 participants met our inclusion criteria for this meta-analysis. Vitamin D supplementation reduced systolic blood pressure (SBP) by 2.44 mm Hg (weighted mean difference [WMD]: −2.44, 95% confidence interval [CI]: −4.86, −0.02), but not diastolic blood pressure (DBP) (WMD: −0.02, 95% CI: −4.04, 4.01) compared with calcium or placebo. Subgroup analysis suggested that the change of blood pressure did not vary markedly across the dose of vitamin D supplementation, study length, or intervention.


Conclusions: Oral vitamin D supplementation may lead to a reduction in systolic blood pressure but not diastolic blood pressure. Given the small number of trials and small but statistically significant reduction in systolic blood pressure from this meta-analysis, further studies are required to confirm the magnitude of the effect of vitamin D on blood pressure reduction and define the optimum dose, dosing interval, and type of vitamin D to administer.


Key Points


* There are physiological explanations for the beneficial effect of vitamin D on the reduction of systolic blood pressure.


* Vitamin D influences the absorption of dietary calcium through a vitamin D-dependent carrier mechanism and, together with the parathyroid hormone, regulates serum calcium levels.


* The renin-angiotensin system is a regulatory cascade that plays an essential role in the regulation of blood pressure, electrolyte, and volume homeostasis.


* This meta-analysis suggests that oral vitamin D supplementation reduced systolic blood pressure by 2.44 mm Hg but not diastolic blood pressure.

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