Q) One of my patients came in and said he had read that vitamin D supplementation will help with hypertension. Now he wants to quit his blood pressure meds and use vitamin D instead. Do you have any background on this?
Vitamin D is critical for utilization of calcium, a vital nutrient for multiple metabolic and cellular processes; deficiency is associated with worsening of autoimmune disorders, osteoporosis, and certain cardiovascular conditions, among others.7 An association between vitamin D level and blood pressure has been recognized for some time, but the pathophysiology is not well understood.
A literature review of studies from 1988 to 2013 found contradictory results regarding vitamin D deficiency and concurrent elevated blood pressure (systolic and/or diastolic), as well as the impact on blood pressure with restoration of vitamin D levels. The findings were limited by several factors, including differences in study design, variables evaluated, and type of vitamin D compound used. The results suggested a link between the renin-angiotensin-aldosterone system, fibroblast growth factor 23/klotho axis, and vitamin D level.8
A study of 158 subjects (98 with newly diagnosed essential hypertension, 60 with normal blood pressure) found significantly lower 25(OH)D3 serum levels in hypertensive patients. Furthermore, the 25(OH)D3 level was significantly correlated with both systolic (r = –0.33) and diastolic blood pressure (r = –0.26). Using multiple regression analysis, after adjustment for age, smoking status, and BMI, the impact of 25(OH)D3 level accounted for 10% of the variation in systolic blood pressure.9
In a mendelian randomization study of 108,173 subjects from 35 studies, an inverse association between vitamin D level and systolic blood pressure (P = .0003) was found. A reduced risk for essential hypertension with increased vitamin D level (P = .0003) was also noted. However, no association was found between increasing vitamin D level and a reduction in diastolic blood pressure
(P = .37).10
With the ever-increasing access to health information from sources such as “Doctor Google,” it can be difficult for a non–health care professional to separate hype from evidence-based recommendations. While current evidence suggests optimal vitamin D levels may be beneficial for improving blood pressure control and may be a useful adjunctive therapy, there is no evidence to support discontinuing antihypertensive therapy and replacing it with vitamin D therapy.
Cynthia A. Smith, DNP, APRN, FNP-BC
Renal Consultants, South Charleston, West Virginia
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