OBJECTIVE: Cardiovascular disease (CVD) is the leading cause of death among American postmenopausal women and all adult Americans. The medical community and the lay community have recently become intrigued with vitamin D and its potential role in reducing the risk of CVD. Research findings from multiple retrospective studies, few prospective studies, and recent nonhuman primate studies have been inconsistent and conflicting. The objective of this study is to review what is known about the topic, what questions remain unanswered, and where the research community should be focusing.

METHODS: A literature search was conducted through PubMed and Google Scholar up to August 1, 2014. One hundred six articles, including 18 double-blind, placebo-controlled, randomized clinical trials, relevant to the study topic were identified. All studies were stratified based on study design and primary outcome. The effects of vitamin D on CVD were reviewed and summarized.

RESULTS: Although there is an abundance of observational studies suggesting an association with CVD protection, the most well-controlled randomized human trial data available show no benefit of vitamin D on CVD. However, highly controlled nonhuman primate studies indicate a beneficial relationship.

CONCLUSIONS: Well-designed research, with CVD as primary outcome, is needed to help bridge the gap in our knowledge on this topic. In the meantime, caution should be applied to avoid overdiagnosis and overtreatment of vitamin D deficiency.