How Vitamin D Supplementation, Cardiovascular Disease Risk Relate

^{By Julie Gould}

According to recent study findings, vitamin D supplementation did not reduce major adverse cardiovascular events, individual cardiovascular disease (CVD) end points, or all-cause mortality. These findings were published online in JAMA Cardiology.

“Observational studies have reported an association between low serum vitamin D levels and elevated risk of [CVD] events, but such studies cannot prove causation because of possible unmeasured confounding,” explained lead researcher Mahmoud Barbarawi, MD, department of internal medicine at the Hurley Medical Center (Flint, Michigan) and colleagues.  

For their study, Dr Barbarawi and his research team measured major adverse cardiovascular events, rates of myocardial infarction, stroke or cerebrovascular accident, CVD mortality, and all-cause mortality among patients receiving vitamin D and placebo.  

“Vitamin D supplementation compared with placebo was not associated with reduced major adverse cardiovascular events (RR, 1.00 [95% CI, 0.95-1.06]; P = .85) nor the secondary end points of myocardial infarction (RR, 1.00 [95% CI, 0.93-1.08]; P = .92), stroke (RR, 1.06 [95% CI, 0.98-1.15]; P = .16), CVD mortality (RR, 0.98 [95% CI, 0.90-1.07]; P = .68), or all-cause mortality (RR, 0.97 [95% CI, 0.93-1.02]; P = .23),” the research team highlighted.  

To better understand takeaways from the study and knowledge gaps that still exist between vitamin D supplementation and cardiovascular events, we spoke with Dr Barbarawi.

Tell us a little about yourself and your research interests.  

My name is Mahmoud Barbarawi, and I am an internal medicine chief resident at Hurley Medical Center/Michigan State University. My research interests include cardiology research as I am aiming to continue my fellowship in cardiovascular medicine.  

Prior to your study, what was known about the link between vitamin D and CVD events?

There was a belief that taking vitamin D could lower the cardiovascular disease risk. This came from multiple observational studies that showed an association between low serum vitamin D level and cardiovascular disease. 

Based on your findings, what important takeaways can health care professionals implement into practice regarding vitamin D?  

Vitamin D supplementation did not confer a cardiovascular benefit, so it should not be given for this purpose.

What knowledge gaps still exist between vitamin D supplementation and cardiovascular events?  

We have studied patients with normal or slightly low serum vitamin D level, so our results cannot be generalized on patients with very low vitamin D level or patients who received very high doses of vitamin D as this was also not studied.

Reference:

Barbarawi M, Kheiri B, Zayed Y, et al. Vitamin D Supplementation and Cardiovascular Disease Risks in More Than 83 000 Individuals in 21 Randomized Clinical Trials: A Meta-analysis [published online June 19, 2019]. JAMA Cardiol. doi:10.1001/jamacardio.2019.1870