Effects of Vitamin D Supplementation on Orthostatic Hypotension: Results From the STURDY Trial

Abstract

Background: Vitamin D3 supplementation is considered a potential intervention to prevent orthostatic hypotension (OH) based on observational evidence that vitamin D levels are inversely associated with OH. With data from The Study to Understand Fall Reduction and Vitamin D in You (STURDY), a double-blind, randomized, response-adaptive trial, we determined if higher doses of vitamin D3 reduced risk of OH.

Methods: STURDY tested the effects of higher (1,000+ IU/day, i.e., 1,000, 2,000, and 4,000 IU/day combined) vs. lower-dose vitamin D3 (200 IU/day, comparison) on fall risk in adults ages 70 years and older with low serum 25-hydroxyvitamin D (25(OH)D, 10-29 ng/ml). OH was determined at baseline, 3, 12, and 24 months by taking the difference between seated and standing blood pressure (BP). OH was defined as a drop in systolic or diastolic BP of at least 20 or 10 mm Hg after 1 minute of standing. Participants were also asked about OH symptoms during the assessment and the preceding month.

Results: Among 688 participants (mean age 77 [SD, 5] years; 44% women; 18% Black), the mean baseline systolic/diastolic BP was 130 (19)/67 (11) mm Hg, serum 25(OH)D was 22.1 (5.1) ng/ml, and 2.8% had OH. There were 2,136 OH assessments over the maximum 2-year follow-up period. Compared with 200 IU/day, 1,000+ IU/day was not associated with seated, standing, or orthostatic BP, and it did not lower risk of OH or orthostatic symptoms.

Conclusions: These findings do not support use of higher doses of vitamin D3 supplementation as an intervention to prevent OH.

Clinical trials registration: Trial Number NCT02166333.

Keywords: blood pressure; hypertension; orthostatic hypotension; trial; vitamin D3.

Graphical abstract

Figure 1.

Kernel density plots of the probability density (y-axis) of (a) seated systolic blood pressure (SBP), (b) standing SBP, and (c) postural change in SBP. Curves represent blood pressure measurements (mm Hg) during baseline (solid line), the 200 IU/day vitamin D assignment follow-up visits (dashed line), and the 1,000+ IU/day vitamin D3 assignment follow-up visits (dotted line). The 1,000+ IU/day includes participants randomized to 1,000, 2,000, or 4,000 IU/day. These figures are restricted to the subpopulation with both baseline and follow-up visits (N = 679).

Figure 2.

The proportion with orthostatic hypotension during the trial and number of participants contributing to orthostatic hypotension assessments by treatment assignment (1,000+ or 200 IU/day). The 1,000+ IU/day includes participants randomized to 1,000, 2,000, or 4,000 IU/day. Point estimates and confidence intervals were estimated using a generalized estimating equation, using the Poisson family, log link, and robust variance estimator. Abbreviations: CI, confidence interval; OH, orthostatic hypotension.