Vitamin D and Cardiovascular Disease: The "Good", the "Bad", and the "Unknown".

Vitamin D is a key regulator of calcium and phosphorus homeostasis; meanwhile, the dietary absence of vitamin D represents the most common nutritional deficiency worldwide. The discovery of vitamin D receptors and conversion enzymes within the cardiovascular system has fueled growing interest in the potential roles of vitamin D beyond bone health. Indeed, preclinical studies have suggested that vitamin D might regulate vascular tone and exert antifibrotic and anti-remodeling effects on the myocardium. Furthermore, a deficit in vitamin D has been associated with an increased risk of hypertension, atherosclerosis, and heart failure. These findings have prompted several interventional studies to investigate whether vitamin D supplementation can mitigate cardiovascular risk. However, current evidence regarding the cardiovascular benefits of vitamin D intake remains inconsistent and inconclusive. This review aims to provide a comprehensive overview of the "good", the "bad", and the "unknown" aspects of the relationship between vitamin D and cardiovascular disease.