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Pediatr Infect Dis J. 2019 Jun;38(6):564-568. doi: 10.1097/INF.0000000000002225.

Effect of High-Dose Vitamin D Supplementation on Upper Respiratory Tract Infection Symptom Severity in Healthy Children.

Author information

From the Department of Pediatrics, Pediatric Research, St. Michael's Hospital.
Dalla Lana School of Public Health, University of Toronto.
Pediatric Outcomes Research Team (PORT), Division of Pediatric Medicine, Department of Pediatrics, The Hospital for Sick Children.
Department of Pediatrics, Faculty of Medicine, University of Toronto.
Institute for Health Policy, Management and Evaluation, University of Toronto.
Child Health Evaluative Sciences, SickKids Research Institute, Toronto, Ontario, Canada.
Department of Pathology and Molecular Medicine, McMaster University.
Health Research Methods, Evidence, and Impact, McMaster University, Hamilton, Ontario, Canada.
The Li Ka Shing Knowledge Institute of St. Michael's Hospital.
Institute for Clinical Evaluative Sciences, Toronto, Canada.
Faculty of Medicine, University of Toronto.
Department of Microbiology, Mount Sinai Hospital/University Health Network.
Department of Laboratory Medicine and Pathobiology, University of Toronto.
Department of Nutritional Sciences, and Faculty of Medicine, University of Toronto.



Observational studies support the role of vitamin D in reducing viral upper respiratory tract infection (URTI) symptom severity in adults and children. This study assessed whether wintertime high-dose vitamin D supplementation (2000 IU/day) reduces URTI symptom severity compared with standard-dose (400 IU/day) supplementation in preschool children. Secondary objectives were to assess effects of high-dose supplementation on outpatient physician visits, emergency department (ED) visits and antibiotic prescriptions for URTI.


This was a secondary analysis of a multisite randomized clinical trial involving 703 healthy 1- to 5-year-old children in Toronto, Canada. High-dose or standard-dose oral vitamin D was randomly assigned for 1 winter season. For each URTI, parents completed symptom checklists based on the Canadian Acute Respiratory and Flu Scale. Symptom severity, frequency of outpatient visits, ED visits and antibiotic prescriptions for URTI between groups were analyzed using negative binomial regression.


URTI symptom severity was not reduced in the high-dose vs. standard-dose group [incidence rate ratio (IRR) = 0.97; 95% confidence interval (CI): 0.76-1.23]. High-dose vitamin D did not decrease frequency of outpatient visits (IRR = 1.16; 95% CI: 0.84-1.60), ED visits (IRR = 1.17; 95% CI: 0.57-2.40) or antibiotic prescriptions (IRR=1.02; 95% CI: 0.61-1.72). Serum 25-hydroxyvitamin D was higher in the high-dose group (48.7‚ÄČng/mL; 95% CI: 46.9-50.5) than the standard-dose group (36.8‚ÄČng/mL; 95% CI: 35.4-38.2; P < 0.001).


High-dose vitamin D supplementation did not reduce URTI symptom severity, outpatient visits, ED visits or antibiotic prescriptions relative to standard-dose. These results do not support vitamin D supplementation above the standard recommended dose for reducing URTI symptoms in children.

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