Previously, some studies have linked vitamin D deficiency to an increased risk of cardiovascular disease. Qi Sun, from Harvard School of Public Health (Massachusetts, USA), and colleagues  evaluated the associations between both dietary and supplemental vitamin D and cardiovascular disease risk. The team assessed data collected on 74,272 women enrolled in the Nurses’ Health Study and 44,592 men enrolled in the Health Professionals Follow-Up Study, none of whom had cardiovascular disease at the start of the study.  At the end of the study, 9,886 cases of coronary heart disease and stroke were documented.  The researchers found a 16% reduction in heart disease among men who met the Dietary Reference Intake (DRI) of vitamin D of at least 600 IU per day, as compared to men with daily intakes of less than 100 IU.  Commenting on the potential mechanism, the team posits that vitamin D may influence the reninangiotensin system (linked to blood pressure regulation), function of the endothelium (the cells lining blood vessels), insulin resistance, and systemic inflammation.   The authors conclude that:  “These observations suggest that a higher intake of vitamin D is associated with a lower risk of [cardiovascular disease] in men.”