Vitamin D is thought to protect the cardiovascular system, although its role is not completely clear. The beneficial effect may occur by vascular calcification inhibition through blockage of both inflammatory cytokines and adhesion molecules. Moreover, calcitriol is a renin negative regulator, interfering in renin-angiotensin-aldosterone system (RAAS) and limiting the production of angiotensin II, an inflammatory and atherogenic cytokine implicated in the development of atheromatous plaques. Epidemiological studies showed an association between osteoporosis and atherosclerosis, which suggests the existence of common underlying mechanisms. We aimed to analyse the relationship between vitamin D serum levels, the severity of atherosclerosis and bone mineral density (BMD) and to explore the importance of both arterial blood pressure and inflammation as mediators of the relationship between vitamin D and atherogenesis.
Patients who underwent carotid endarterectomy in the Vascular Surgery Department of Hospital de Santa Maria were included. A structured clinical protocol was applied to those who agreed to participate and many important personal data (age; gender; traditional cardiovascular risk factors; date of the surgery; personal and family history of bone fractures, osteoporosis and other relevant diseases; patient’s medication) were recorded, as well as many variables, like calcidiol, degree of carotid stenosis, BMD (obtained by dual-energy X-ray absorptiometry), mean arterial pressure (MAP) and C-reactive protein (CRP).
The correlations between calcidiol and both degree of stenosis and BMD were not statistically significant. There were no cross-sectional association between MAP and serum calcidiol or the percentage of stenosis and the latter and BMD levels were not significantly different in patients with and without sufficient/adequate vitamin D levels.
Despite the existing evidence that vitamin D has a protective role in cardiovascular system through many pathways, our results do not substantiate that premise. Mean arterial blood pressure and C-reactive protein didn’t correlate with both vitamin D and percentage of stenosis. It is important to have in mind that this study had some limitations (like sample dimension, the cross-sectional design and the exclusion of many confounders). Nevertheless we highlight the importance of vitamin D in cardiovascular system, encouraging the reflection about points that could strengthen the results of future projects.