Cardiovascular effects of vitamin D supplementation still uncertain, trial finds
Older adults who were randomized to vitamin D supplementation had a slightly lower rate of cardiovascular events, particularly myocardial infarction, but the overall difference from placebo was not significant, an Australian trial found.
In older adults, vitamin D supplementation was associated with a slightly lower rate of myocardial infarction than placebo, but supplements did not significantly reduce cardiovascular events overall, a recent trial found.
The trial randomized 21,315 Australians ages 60 to 84 years at enrollment in 2014 to 2020 to either 60,000 IU/month vitamin D3 (n=10,662) or placebo (n=10,653) taken orally for up to five years. Exclusion criteria included hypercalcemia, hyperparathyroidism, kidney stones, osteomalacia, sarcoidosis, and use of more than 500 IU/day supplemental vitamin D at baseline. Results were published by The BMJ on June 28.
A total of 16,882 participants completed the intervention, and 1,336 experienced the primary outcome of a major cardiovascular event, including myocardial infarction, stroke, and coronary revascularization (6.0% of the vitamin D group vs. 6.6% on placebo; hazard ratio [HR], 0.91 [95% CI, 0.81 to 1.01]). The effect of vitamin D appeared to slightly be greater among those taking statins or other cardiovascular medications at baseline (HR, 0.84; 95% CI, 0.74 to 0.97), although the P value for interaction was not significant (<0.05).
Overall, the difference in cumulative incidence at five years was 5.8 fewer cardiovascular events per 1,000 participants taking vitamin D (95% CI, −12.2 to 0.5 per 1,000 participants). The vitamin D group had a lower rate of myocardial infarction (HR, 0.81, 95% CI, 0.67 to 0.98), but there was no difference in the rate of stroke (HR, 0.99; 95% CI, 0.80 to 1.23).
“Vitamin D supplementation might reduce the incidence of major cardiovascular events, although the absolute risk difference was small and the confidence interval was consistent with a null finding,” the study authors concluded. They noted that future research might appropriately focus on potential interactions between vitamin D and cardiovascular therapies, although the larger effect in this subgroup of patients might just reflect their higher risk of cardiovascular events. Overall “these findings suggest that conclusions that vitamin D supplementation does not alter risk of cardiovascular disease are premature,” they said.