High Levels Of Vitamin-D Too Can Cause Fatal Stroke Or Coronary Attacks
Vitamin D receptors have been found ubiquitously in the human body including in cells of the vessel wall and the heart. Human vascular smooth muscle cells express the 1-hydroxylase enzyme enabling the conversion of circulating 25-hydroxyvitamin D [25(OH)D] to the active hormone 1,25-dihydroxyvitamin D. Mechanisms have been postulated to explain the link between vitamin D deficiency and cardiovascular diseases and mortality including overexpression of renin and parathyroid hormone. Less clear is the reason for higher levels of vitamin D to be associated with increased cardiovascular disease mortality.
An observational cohort study, the CopD Study, is reported with an aim to determine the association between cardiovascular, stroke and acute myocardial infarct mortality and serum levels of 25(OH)D. Serum 25(OH)D was analyzed from 247,574 subjects from the Copenhagen general practice sector (161,428 women and 86,146 men), from the years 2004 to 2011.
The results are published here. The salient findings are:
1. Low and high levels of 25-hydroxyvitamin D were associated with cardiovascular disease, stroke and acute myocardial mortality in a non-linear, reverse J-shaped manner, with highest risk at lower levels.
2. The lowest mortality rates were observed at approximately 70 nmol/L, 75 nmol/L and 70 nmol/L for cardiovascular disease, stroke and acute MI mortality, respectively, when adjusted for age, sex and season.
3. The hazard ratios were all higher at lower serum 25-hydroxyvitamin D levels than at higher levels.
4. Men tended to be more at risk at lower levels than women. In the present study women might have a lower cut-off at 30 nmol/L, but men seem to have a cut-off at 50 nmol/L, at least in regard to cardiovascular disease mortality.
The authors concluded with following "there is a need for randomized clinical trials which also include information on the effects of 25-hydroxyvitamin D levels above 100 nmol/L."
Article citation: Durup, D.; et. al. A reverse J-shaped association between serum 25-hydroxyvitamin D and cardiovascular disease mortality – the CopD-study. J Clin Endocrinol Metab 2015 DOI: http://dx.doi.org/10.1210/jc.2014-4551