Study Search and Selection Flow Diagram. Search terms for vitamin D included vitamin D, 25hydroxy-vitamin D, 1,25dihydroxy-vitamin D, calcidiol, and calcitriol. Search terms for cardiovascular disease (CVD) included cardiovascular disease, ischemic heart disease, coronary artery disease, cardiovascular mortality, myocardial infarction, and stroke. Initial search results were further limited to English-language articles, human studies, and studies of adults 18 years. In each box, the sum of studies in all categories may exceed the total number because of overlapping classification.