Vitamin D is a steroid hormone that exerts pleiotropic effects in the cardiovascular field, including the protection of endothelial function, the control of inflammation, the regulation of intracellular calcium homeostasis, and the modulation of the renin-angiotensin-aldosterone system (RAAS). Hypovitaminosis D, defined as vitamin D ≤ 20 ng/mL, is frequently associated with hypertension, the development of heart failure, and higher morbidity and mortality after a myocardial infarction (MI). Despite initial enthusiasm regarding the potential benefits of vitamin D supple- mentation in the management of cardiovascular diseases (CVDs), recent clinical trials have yielded contrasting results regarding its effectiveness in a clinical setting. Consequently, the benefits of vitamin D in CVDs are currently called into question. This chapter aims to describe the physiological effects of vitamin D on cardiovascular health and the current data on its supplementation in patients with CVDs.
