Vitamin D, thrombosis, and hemostasis: more than skin deep.

Vitamin D(3) deficiency is a highly prevalent condition worldwide. Clinically, vitamin D(3) has a key role in calcium homeostasis and bone mineralization and has recently been implicated in the pathogenesis and/or progression of several acute and chronic illnesses, including cardiovascular disease (CVD). Accumulating evidence from observational, prospective studies suggests that low levels of serum 25-hydroxyvitamin D(3) are independently associated with an increased risk of CVD events and death. The molecular mechanisms of this association remain incompletely understood. A variety of biologically plausible mechanisms may mediate a cardiovascular role for the active metabolite of vitamin D(3). 1-α,25-dihydroxyvitamin D(3) regulates the renin-angiotensin system, suppresses proliferation of vascular cell smooth muscle, improves insulin resistance and endothelial cell-dependent vasodilation, inhibits myocardial cell hypertrophy, exerts anticoagulant and antifibrotic activity, and modulates macrophage activity and cytokine generation. Overall, the high prevalence of vitamin D(3) deficiency and the plausible biological mechanisms linking this to CVD risk suggest that the treatment of vitamin D(3) deficiency to prevent CVD is a promising field to explore. Large placebo-controlled randomized clinical trials are urgently needed to determine whether vitamin D supplementation could have any potential benefit in reducing future CVD events and mortality risk. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.