An intention-to-treat analysis found no statistically significant difference in the number of laboratory-confirmed all-cause viral respiratory infections among children receiving high doses of vitamin D (2,000 IU/day) compared with those receiving standard doses (IRR 0.97, 95% CI 0.80-1.16), reported Mary Aglipay, of St.
Overall, 703 children were randomized, with 354 receiving the standard dose 400 IU/day of vitamin D (consistent with guidelines from the American Academy of Pediatrics), while 349 received the high dose vitamin D at 2,000 IU/day (within the upper limit of vitamin D intake specified by the Institute of Medicine).
The median time to first laboratory-confirmed upper respiratory infection was a little over 3 months in both the high-dose and standard dose groups (3.95 months, 95% CI 3.02-5.95 vs 3.29 months, 95% CI 2.66-4.14, respectively).
The authors also noted that this reduction was "smaller than the minimal clinically important difference." There was a significant difference in serum 25-hydroxyvitamin D levels among children in the high dose group compared with the standard dose group.
While the authors noted that there was no protective effect observed with high-dose vitamin D among all children, they hypothesized that it might be effective among certain subpopulations.