Effects of Vitamin D supplementation on markers of vascular function after myocardial infarction—A randomised controlled trial

Abstract Background Low vitamin D levels are common, and are associated with a higher incidence of future vascular events. We tested whether vitamin D supplementation could improve endothelial function and other markers of vascular function in patients with a history of myocardial infarction. Methods Parallel group, placebo-controlled, double-blind randomised trial. Patients with a history of myocardial infarction were randomised to receive 100,000 units of oral vitamin D3 or placebo at baseline, 2 months and 4 months. Outcomes were measured at baseline, 2 and 6 months. Reactive hyperaemia index on fingertip plethysmography was the primary outcome. Secondary outcome measures included blood pressure, cholesterol, C-reactive protein, von Willebrand factor, tumour necrosis factor alpha, E-selectin, B-type natriuretic peptide, thrombomodulin and 25-hydroxyvitamin D levels. Results 75 patients were randomised, mean age 66 years. 74/75 (99%) completed 6 month follow-up. 25 hydroxyvitamin D levels increased in the intervention group relative to placebo (+ 13 vs + 1 nmol/L, p = 0.04). There was no between-group difference in change in reactive hyperaemia index between baseline and 6 months (− 0.18 vs − 0.07, p = 0.40). Of the secondary outcomes, only C-reactive protein showed a significant decline in the intervention arm relative to placebo at 6 months (− 1.3 vs 2.0 mg/L, p = 0.03). Systolic blood pressure (+ 1.4 vs + 2.3 mm Hg, p = 0.79), diastolic blood pressure (+ 2.0 vs + 0.8 mm Hg, p = 0.54) and total cholesterol (+ 0.26 vs + 0.24 mmol/L, p = 0.88) showed no between-group difference at 6 months. Conclusions Supplementation with vitamin D did not improve markers of vascular function in patients with a history of myocardial infarction.