There’s little point in taking vitamin D supplements in a bid to lower the risk of cardiovascular disease, a meta-analysis of RCTs has found.
Research published in JAMA Cardiology looked at 21 clinical trials, including three Australian studies, involving more than 83,000 participants.
What they found was that vitamin D supplementation was not associated with reduced risks of major adverse cardiovascular events, myocardial infarction, CVD mortality or all cause mortality compared with placebo.
That conclusion held fast regardless of differing doses of vitamin D taken and for men and women.
The belief that vitamin D might have been protective stemmed from observational studies which had shown significant associations between low levels of the vitamin, CVD events and all-cause mortality.
However, the authors said these studies were susceptible to uncontrolled confounding by outdoor physical activity, nutritional status and prevalent chronic disease which might influence serum 25 hydroxyvitamin D levels.
“The popularity of vitamin D supplementation is at least partly owing to the misinterpretation of impressive epidemiologic associations between vitamin D status and a breadth of health metrics, leading to a potentially flawed assumption of causation,” the authors of an accompanying editorial comment said.
“There are a lot of things people can do to lower cardiovascular risk – doing regular exercise, healthy eating, stopping smoking, and controlling hypertension [high blood pressure] and diabetes. But giving vitamin D supplements for the sake of lowering cardiovascular risk is not recommended,” the study’s lead author, Dr Mahmoud Barbarawim, said.