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

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.