Vitamin D has been investigated for its potential role in supporting cardiovascular health, primarily due to the observation that deficiency in this vitamin is associated with an increased risk of hypertension, coronary artery disease, heart failure, and other cardiovascular conditions. Mechanistically, vitamin D receptors are present in many cardiovascular tissues, and vitamin D is thought to modulate inflammation, vascular calcification, and endothelial function.

However, while observational studies have consistently shown associations between low vitamin D levels and increased cardiovascular risk, randomized controlled trials (RCTs) and meta-analyses have generally not demonstrated a clear benefit of vitamin D supplementation in reducing cardiovascular events in the general population. For instance, large RCTs like the VITAL study (Manson JE, et al., NEJM 2019) found no significant reduction in major cardiovascular events with vitamin D supplementation compared to placebo. Some subgroups, such as those with severe deficiency, may derive some benefit, but this evidence is not strong or consistent.

In summary, while there is scientific rationale and observational evidence linking vitamin D status to cardiovascular health, current interventional evidence does not robustly support vitamin D supplementation as an effective treatment or preventive measure for cardiovascular disease in most individuals. Supplementation is primarily justified for bone health and in cases of deficiency, rather than for cardiovascular protection.