Patients were divided into three groups based on their vitamin D levels: “normal,” for those who had over 30 nanograms per milliliter of blood, “low” for those with levels of 15 to 30, and “very low” for those with levels less than 15.
Those with the lowest vitamin D levels were 77 percent more likely to die during the follow-up, 78 percent more likely to have a stroke and 45 percent more likely to develop coronary artery disease than those with normal levels. They were twice as likely to develop heart failure as those with normal levels. And even those who had moderate deficiencies were at higher risk, the researchers said.