Vitamin D therapy in individuals with prehypertension or hypertension: the DAYLIGHT trial

Circulation. 2015 Jan 20;131(3):254-62. doi: 10.1161/CIRCULATIONAHA.114.011732. Epub 2014 Oct 30.

Abstract

Background: A large body of epidemiological and experimental evidence suggests that vitamin D deficiency may promote hypertension. This raises the possibility that vitamin D supplementation could be a simple intervention to reduce blood pressure, but data from prospective, randomized trials are limited.

Methods and results: A double-blind, randomized, controlled trial was conducted at 4 sites in the United States. We enrolled 534 individuals 18 to 50 years of age with low vitamin D status (25-hydroxyvitamin D levels ≤25 ng/mL) and systolic blood pressure of 120 to 159 mm Hg. Participants were randomized to high-dose (4000 IU/d) versus low-dose (400 IU/d) oral vitamin D3 for 6 months. The primary end point was change in mean 24-hour systolic blood pressure. Secondary end points included change in ambulatory diastolic blood pressure and clinic systolic and diastolic blood pressures. The median age was 38 years, and 62% of participants were men. Forty-six percent of participants were white, and 48% were black. The median 25-hydroxyvitamin D level at baseline was 15.3 ng/mL. Four-hundred fifty-five participants (85%) had at least 1 follow-up blood pressure measurement; 383 participants (72%) completed the full 6-month study. At the end of the study, there was no significant difference in the primary end point (change in mean 24-hour systolic blood pressure, -0.8 versus -1.6 mm Hg in the high-dose and low-dose arms; P=0.71) or in any of the secondary end points. Furthermore, there was no evidence of association between change in 25-hydroxyvitamin D and change in 24-hour systolic blood pressure at 6 months (Spearman correlation coefficient, -0.05, P=0.34). Results were consistent across prespecified subgroups.

Conclusions: Vitamin D supplementation did not reduce blood pressure in individuals with prehypertension or stage I hypertension and vitamin D deficiency. Our findings suggest that the association between vitamin D status and elevated blood pressure noted in observational studies is not causal.

Clinical trial registration url: http://www.clinicaltrials.gov. Unique identifier: NCT01240512.

Keywords: blood pressure; dietary supplements; hypertension; vitamin D deficiency.

Publication types

  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Blood Pressure / drug effects
  • Blood Pressure / physiology
  • Cholecalciferol / blood
  • Cholecalciferol / pharmacology
  • Cholecalciferol / therapeutic use*
  • Double-Blind Method
  • Female
  • Follow-Up Studies
  • Humans
  • Hypertension / blood
  • Hypertension / diagnosis
  • Hypertension / drug therapy*
  • Male
  • Middle Aged
  • Prehypertension / blood
  • Prehypertension / diagnosis
  • Prehypertension / drug therapy*
  • Vitamin D Deficiency / blood
  • Vitamin D Deficiency / diagnosis
  • Vitamin D Deficiency / drug therapy*

Substances

  • Cholecalciferol

Associated data

  • ClinicalTrials.gov/NCT01240512