Vitamin D and the cardiovascular system

Abstract

Vitamin D, a secosteroid hormone, affects multiple biological pathways via both genomic and nongenomic signalling. Several pathways have potential benefit to cardiovascular health, including effects on parathyroid hormone, the renin-angiotensin-aldosterone system, vascular endothelial growth factor and cytokine production, as well as direct effects on endothelial cell function and myocyte calcium influx. Observational data supports a link between low vitamin D metabolite levels and cardiovascular health. Cross-sectional data shows associations between low 25-hydroxyvitamin D levels and stroke, myocardial infarction, diabetes mellitus, hypertension, and heart failure. Longitudinal data also suggests a relationship with incident hypertension and new cardiovascular events. However, these associations are potentially confounded by reverse causality and by the effects that other cardiovascular risk factors have on vitamin D metabolite levels. Intervention studies to date suggest a modest antihypertensive effect of vitamin D, no effect on serum lipids, a small positive effect on insulin resistance and fasting glucose, and equivocal actions on arterial stiffness and endothelial function. Analysis of cardiovascular event data collected from osteoporosis trials does not currently show a clear signal for reduced cardiovascular events with vitamin D supplementation, but results may be confounded by the coadministration of calcium, and by the secondary nature of the analyses. Despite mechanistic and observational data that suggest a protective role for vitamin D in cardiovascular disease, intervention studies to date are less promising. Large trials using cardiovascular events as a primary outcome are needed before vitamin D can be recommended as a therapy for cardiovascular disease.

The use of laser Doppler blood flow to assess the effect of acute administration of vitamin D on micro vascular endothelial function in people with diabetes

“…Numerous studies have been conducted showing a link between the concentration of vitamin D in the blood and diabetes, heart disease and stroke [16]. The observation that vitamin D is inversely related to diseases such as MS and heart disease has caused the general belief that vitamin D is beneficial to people with cardiovascular disease [16].…”

“…The observation that vitamin D is inversely related to diseases such as MS and heart disease has caused the general belief that vitamin D is beneficial to people with cardiovascular disease [16]. This may be true, but in studies where vitamin D has been given at 4,000 IU per day for 3 months sometimes show a positive effect on vascular endothelial function and sometimes no effect at all.…”

“…Numerous studies have associated diabetes and heart disease with low concentrations of vitamin D in the blood [16]. Numerous studies have also studied the effects of 3-4 months of vitamin D administration on endothelial function…”

“…Diabetes is associated with low vitamin D in the serum [20]. When people with diabetes were administered vitamin D, some studies show improved flow mediated dilation and others do not [16]. One pathway altered by vitamin D is a direct effect on phosphotidyl inositol 3 kinase (PI3K) in endothelial cells [21].…”

“…It is of no surprise then, that the brachial artery response to vascular occlusion (flow mediated vasodilation) is increased in people who are on vitamin D supplements [13,[25][26][27][28]. Complicating matters further, measurements are almost never made until 3 months after vitamin D administration; there are few studies on acute administration of vitamin D even in young people [16]. Finally, the response to arterial shear receptors may not be predictive of micro vascular function.…”