While this study was conducted on a subgroup of the population and the study itself was not easily accessible from the article, as far as I could see, the results are really interesting. In short, if you adhere to the RDI (Recommended Daily Intake) of Vitamin-D, you just might not get enough. Arterial stiffness has been associated with all kinds of problem with the cardiovascular system. Supplementing your, most likely, Vitamin-D-deficient diet with more Vitamin D seem to be a healthy thing to do. Now we need more studies supporting the result of this study.