In conclusion, our findings indicate that Vit D3 repletion may improve vascular function in high risk AA study participants with Vit D deficiency, obesity and controlled hypertension, and that flOPN could be a more sensitive marker of vascular function, compared to FGF-23 in this population, with no significance related to PAI-1. Here, FGF23 is linked to obesity due to melanocortin 4 receptor deficiency.