This study, called a meta-analysis, combined the results of 21 randomized clinical trials with about 83,000 patients to look at whether vitamin D supplementation was associated with reduced risk of cardiovascular disease events such as heart attack or stroke.

Some observational studies have suggested an association between low blood levels of vitamin D and an increased risk of cardiovascular disease events. This study reports that compared with placebo, vitamin D supplementation wasn’t associated with a reduction in major adverse cardiovascular events (heart attack, stroke, or death from cardiovascular disease) or overall death. The results were similar between different doses of vitamin D and for men and women. A limitation of the study is that the definition of major adverse cardiovascular events varied between the clinical trials.