FRIDAY, July 14, 2023 (HealthDay News) — For generally healthy older adults, vitamin D₃ supplementation at 1,600 IU/day or 3,200 IU/day is associated with a reduction in the incidence of atrial fibrillation (AF) during five years of follow-up, according to a research letter published online June 10 in the American Heart Journal.

Jyrki K. Virtanen, Ph.D., from the University of Eastern Finland in Kuopio, and colleagues compared the effects of five-year vitamin D₃ supplementation versus placebo on AF risk among generally healthy men (aged 60 years and older) and postmenopausal women (aged 65 years and older). A total of 2,495 participants were randomly assigned to receive 1,600 IU/day or 3,200 IU/day vitamin D₃ or placebo (832, 833, and 830 participants, respectively).

The researchers found that 190 participants were diagnosed with AF during a mean follow-up of 4.1 years. The absolute incidence rate difference was 0.57 per 100 person-years between the 1,600 IU/day and placebo arms and 0.68 per 100 person-years between the 3,200 IU/day and placebo arms. The AF risk was 27 and 32 percent lower in the 1,600-IU/day and 3,200-IU/day arms, respectively, compared with the placebo arm. The risk was reduced by 30 percent in the combined vitamin D₃ arms versus the placebo arm. When excluding participants diagnosed with AF during the first two years of follow-up, the risk reductions were larger.

“Our findings suggest possible benefit in AF prevention with high-dose vitamin D supplementation in an elderly population, despite the relatively high baseline 25(OH)D concentrations,” the authors write.

Several authors disclosed ties to industry.

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