High-dose vitamin D supplementation fails to prevent respiratory infection in seniors
Monthly supplementation with high-dose vitamin D does little to stave off the risk of developing acute respiratory infection (ARI) in older adults with low prevalence of profound vitamin D deficiency, a study has found.
Researchers randomized 5,110 adults aged 50–84 years (mean age, 66 years; 58 percent male; 83 percent of European/other descent) to receive an initial oral dose of 200,000 IU vitamin D3 followed by 100,000 IU monthly (n=2,558) or placebo (n=2,552) for a median of 1.6 years. Participants completed monthly questionnaires to report upper and lower ARIs.
Mean (SD) baseline blood 25-hydroxyvitamin D (25OHD) level was 63 nmol/L, with 25 percent of participants having <50 nmol/L. In a random sample of 441 individuals, mean 25OHD levels increased to 135 nmol/L with vitamin D supplementation at 3 years, but remained stable at 63 nmol/L with placebo.
During follow-up, at least one ARI occurred in 3,737 participants: 74.1 percent in the vitamin D group vs 73.7 percent in the placebo group. The difference in ARI risk was not significant between the two groups (hazard ratio, 1.01, 95 percent CI, 0.94–1.07).
Similar results were seen in most subgroups, including that defined by baseline 25OHD <50 nmol/L, and in analyses of the upper/lower components of the ARI outcome.
In light of the findings, the researchers do not recommend monthly dosing of vitamin D for the prevention of ARI.