There are no benefits from vitamin D supplementation in reducing the risk of major adverse cardiovascular events or all-cause mortality, according to a meta-analysis published in JAMA Cardiology.
Researchers analyzed data from 83,291 patients enrolled in 21 randomized, placebo-controlled clinical trials of at least 1 year of vitamin D supplementation.
They found the incidence of major adverse cardiovascular events was the same among patients taking vitamin D supplements and those taking placebo (risk ratio, 1; P = .85). Even stratifying by age, sex, postmenopausal status, pretreatment vitamin D levels, vitamin D dosage and formulation, chronic kidney disease, or excluding studies that used vitamin D analogues made no significant difference.
However, there was the suggestion of reduced incidence of major adverse cardiovascular events with vitamin D supplementation in individuals of advanced age, but the authors wrote that the finding should be interpreted with caution.
The analysis found no benefit from vitamin D supplementation on the secondary endpoints of MI, stroke, cardiovascular mortality, or all-cause mortality risk.
Mahmoud Barbarawi, MD, from the Hurley Medical Center at Michigan State University, East Lansing, and coauthors commented that previous observational studies have found significant associations between low vitamin D levels and cardiovascular events and all-cause mortality.
“However, observational studies are susceptible to uncontrolled confounding by outdoor physical activity, nutritional status, and prevalent chronic disease, which may influence serum 25-hydroxyvitamin D levels,” they wrote.
This updated analysis extended earlier clinical trial findings and added in some more-recent randomized trial outcomes, including the massive VITAL trial, which showed that neither daily vitamin D nor omega-3 fatty acids reduce cancer or cardiovascular event risk (N Engl J Med. 2019;380:33-44).
Still, the authors noted that most of the trials included in the analysis had not prespecified cardiovascular disease as the primary endpoint and were underpowered to detect an effect on cardiovascular events. They also pointed out that few trials included data on heart failure, and a previous meta-analysis had suggested a potential benefit of supplementation in reducing the risk of this condition.
“Additional trials of higher-dose vitamin D supplementation, perhaps targeting members of older age groups and with attention to other [cardiovascular disease] endpoints such as heart failure, are of interest,” they wrote.
One author reported receiving funding from the National Institutes of Health and in-kind support from the pharmaceutical sector for a vitamin D study. No other disclosures were reported.
SOURCE: Barbarawi M et al. JAMA Cardiol. 2019 Jun 19. doi: 10.1001/jamacardio.2019.1870.