RESUMEN
CONTEXT: Cholecalciferol (vitamin D3) improves vascular function and inflammation, potentially providing an explanation for the proposed cardiovascular protection of vitamin D. OBJECTIVE: We investigated whether cholecalciferol supplementation reduces postprandial arterial dysfunction and inflammation. DESIGN: Randomized, 1:1, double-blind trial. SETTING: Diabetes and Vascular Center, Franciscus Gasthuis, Rotterdam, The Netherlands. PATIENTS: Twenty-four healthy, premenopausal, overweight or obese, vitamin D-deficient women. INTERVENTIONS: A single high (300,000 IU) or low dose (75,000 IU) of cholecalciferol. MAIN OUTCOME MEASURES: The effect of low- and high-dose cholecalciferol on postprandial leukocyte activation markers, pulse wave velocity (PWV), and augmentation index (AIx) during an oral fat loading test, expressed as area under the curve (AUC). RESULTS: High- and low-dose supplementation increased vitamin D by 163% ± 134% (P < 0.001) and 66% ± 59% (P < 0.001), respectively. Monocyte CD11b-AUC slightly increased after low but not high dose (6% ± 2%, P = 0.012, and 4% ± 1%, P = 0.339, respectively). There were no significant effects on postprandial PWV or AIx by high- or low-dose vitamin D. Fasting complement component 3 (C3) levels decreased by 5.9% (P = 0.004) in the high-dose group and by 4.0% (P = 0.018) in the low-dose group. CONCLUSION: A single dose of vitamin D does not seem to reduce arterial stiffness and leukocyte activation in overweight, vitamin D-deficient women. Vitamin D may decrease fasting C3. Possibly, higher vitamin D concentrations may be needed to decrease inflammation and improve vascular function in overweight or obese vitamin D-deficient women.