1. Vitamin D deficiency is associated with high blood pressure and cardiovascular disease.
2. Ameliorating vitamin D deficiency through supplementation did not lower blood pressure in this study.
Evidence Rating Level: 1 (Excellent)
Study Rundown: Previous work has demonstrated that low serum levels of vitamin D are associated with elevated blood pressure. Vitamin D receptors are found on smooth muscle and endothelial cells, which represents a plausible mechanism through which vitamin D might act on the vascular system. This meta-analysis sought to address whether or not vitamin D supplementation in patients deficient in vitamin D would lower blood pressure. Through analysis of several randomized clinical trials, this study did not find any anti-hypertensive effect of vitamin D supplementation.
Limitations to this paper include the caliber of the studies included in the meta-analysis, as most were single-center trials that recruited less than 1000 patients. It is also indeterminate what the optimal dose might be of vitamin D supplementation. The authors suggest that many of the studies this paper makes reference to were using doses too low for adequate serum levels. However, excess vitamin D further can result in toxicity if ingested in very high doses, resulting in renal calculi, gastrointestinal symptoms, or even risk of cardiac events.
Click to read the study in JAMA Internal Medicine
Relevant Reading: Effect of Vitamin D Supplementation on Blood Pressure
In-Depth [meta-analysis]: The authors used MEDLINE and other sources to identify clinical trials containing search terms related to vitamin D and hypertension. Studies that measured baseline 25-hydroxyvitaminD (25OHD) versus blood pressure or surrogate markers of cardiovascular risk were included in study. All trials had an intervention arm of minimum 4 weeks of treatment with vitamin D2, vitamin D3, calcitriol, paricalcitol, or doxerocalciferol. Forty-six trials, including a total of 4,541 patients, were ultimately included in analysis. The primary outcome was change in office-measured systolic and diastolic blood pressure readings from baseline through follow-up.
Both individual (for 27 trials) and trial data were analyzed. At the trial level, no effect of vitamin D supplementation was seen on either systolic (effect size 0.0; 95%CI −0.8 to 0.8 mm Hg; p = 0.97) or diastolic (effect size −0.1; 95%CI −0.6 to 0.5 mmHg; p = 0.84) blood pressures. Similar results were found upon analyzing individual data. Subgroup analyses were also unrevealing, and did not suggest any particular groups that would benefit more than others from supplementation.
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