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
