Abstract 49: The Effects of Vitamin D Supplementation on Subclinical Cardiovascular Disease: Results From the Sturdy Trial

Background: In observational studies, older adults with insufficient or deficient serum vitamin D levels are at higher risk of cardiovascular disease (CVD), but randomized trials have failed to demonstrate reduction in CVD risk from vitamin D supplementation. This is possibly because the doses of vitamin D supplements tested were too low. Objective: To determine if higher doses of vitamin D supplementation lower high sensitivity cardiac troponin level (hs-cTnI) and N-terminal pro b-type natriuretic peptide (NT-proBNP), markers of subclinical CVD. Methods: The Study to Understand Fall Reduction and Vitamin D in You (STURDY) was a double-blind, randomized, response-adaptive trial that tested the effects of 4 doses of vitamin D3 supplementation (200, 1000, 2000, and 4000 IU/day) on fall risk in adults aged ≥70 years old with low serum 25-hydroxyvitamin D levels (10-29 ng/ml). Hs-cTnI and NT-proBNP levels were measured at baseline and at 3-, 12- and 24-month follow-up visits. For analysis, participants were divided into low (200 IU/day) and high dose (1000+ IU/day) vitamin D treatment groups. The effects of vitamin D dose on hs-cTnI and NT-proBNP were assessed via mixed effects tobit models. Results: Among 688 participants (mean age of 77 ± 5 years, 44% were women, and 18% were Black), 50.7% were in the high-dose treatment group (1000+ IU/day). Hs-cTnI increased in both the low and high dose groups by 5.1% and 5.8%, respectively; likewise, NT-proBNP increased in both groups by 11.3% and 9.3%, respectively ( Figure). Compared to the low-dose group, high-dose vitamin D treatment did not affect hs-cTnI (1.7 % difference; 95% CI: -5.3, 9.3) or NT-proBNP (-1.8 % difference; 95% CI: -9.3, 6.3). Conclusions: Compared to low dose vitamin D supplementation, a higher dose did not affect markers of subclinical CVD in older adults with low serum vitamin D levels. These findings do not support higher doses of vitamin D as an intervention to reduce the risk of CVD in this population.