Study Questions Effectiveness of Vitamin D Supplementation for CVD Prevention
A high-dose vitamin D supplement taken once a month does not decrease the risk for cardiovascular disease (CVD), according to the results of a recent study.
The randomized, double-blind, placebo-controlled trial included adults aged 50 to 84 years recruited from family practices in New Zealand. Once a month, researchers mailed an oral 100,000 IU dose vitamin D3 supplement to 2558 participants and placebo to 2552 participants. Vitamin D levels were obtained at baseline for all participants, and 438 (10%) participants were randomly selected for additional blood samples that were taken at 6, 12, 24, and 36 months.
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The outcomes included incidents of CVD or death, as well as myocardial infarction, angina, heart failure, hypertension, arrhythmias, arteriosclerosis, stroke, and venous thrombosis.
At baseline, the mean deseasonalized 25(OH)D concentration was 26.5 (9.0) ng/mL, and 1270 (24.9%) of participants were vitamin D deficient.
The mean follow-up 25(OH)D concentrations from participants who provided additional blood samples showed that vitamin D levels were more than 20 ng/mL higher in participants receiving the supplement compared with participants receiving the placebo.
Overall, researchers found no difference between CVD occurrence in the vitamin D group and the placebo group (11.8% vs 11.5%, respectively). The results were similar in participants with vitamin D deficiency at baseline.
“This result does not support the use of monthly vitamin D supplementation for [preventing CVD]. The effects of daily or weekly dosing require further study,” the researchers concluded.
—Melissa Weiss
Reference:
Scragg R, Stewart AW, Waayer D, et al. Effect of monthly high-dose vitamin D supplementation on cardiovascular disease in the vitamin D assessment study: a randomized clinical trial [published online April 5, 2017]. JAMA Cardiol. doi:10.1001/jamacardio.2017.0175.