I didn't read the actual study, I just read the sciencedaily blurb. Sciencedaily reported the study as not having a control group taking a placebo? Is that possible?

They had 2 groups, one taking 400 iu and one taking 2000 iu.

"Study subjects taking 400 IU of vitamin D per day did not achieve vitamin D sufficiency, while their peers who took 2,000 IU of vitamin D per day on average became vitamin D sufficient.

Researchers measured arterial stiffness in study subjects using pulse wave velocity (PWV), a non-invasive procedure where a pulse is emitted at two arterial sites. The pulse's transit time and distance travelled help researchers reliably calculate arterial stiffness. Results from the study showed that vitamin D may protect vascular systems and that sufficient supplementation of vitamin D could elicit favorable alterations in the arterial system and in cardiovascular function in general."

Is your objection that they didn't have another group taking a placebo of some sort?