Objectives: There are two major forms of vitamin D, vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). We studied
the effect of the different vitamin D fractions (D3/D2) on arterial wall properties in coronary artery disease (CAD) patients.
Methods: We included 252 subjects with CAD. Endothelial function was evaluated by flow mediated dilation (FMD). Carotid femoral
pulse wave velocity (PWV) was measured as an index of arterial stiffness and augmentation index (AI) as a measure of reflected waves.
Measures for 25(OH)D2 and 25(OH)D3 were performed using Liquid Chromatography Mass Spectrometry technology.
Results: From the study population, 155(62%), 66(26%) and 31(12%) were categorized as having vitamin D deficiency, insufficiency
and sufficiency respectively. There was no difference between subjects with vitamin D deficiency, insufficiency and sufficiency in FMD,
AI and PWV (p=NS for all). Subjects with vitamin D insufficiency/deficiency had significantly higher D2 to D ratio compared to subjects
with vitamin D sufficiency. Interestingly, FMD was positively associated with D2 to D ratio (rho=0.13, p=0.02) and subjects with
D2 levels<0.3ng/ml had impaired FMD compared to those with increased D2 levels (p=0.048).
Conclusion: Vitamin D insufficiency/deficiency is highly prevalent in CAD subjects. Vitamin D2 concentrations are positively associated
with endothelial function. These findings may suggest a beneficial role of vitamin D2 levels in vascular health.