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Just 300 IU daily of vitamin D reduced respiratory infections by 50% – RCT Aug 2012

Randomized Trial of Vitamin D Supplementation and Risk of Acute Respiratory Tract Infection in Mongolia

Pediatrics August 20, 2012
Carlos A. Camargo Jr, MD, DrPHa,b,c, Davaasambuu Ganmaa, MD, PhDb,c,d, A. Lindsay Frazier, MD, MPHb,c,e, Franca F. Kirchberg, BSa, Jennifer J. Stuart, ScMc,g, Ken Kleinman, ScDb,f, Nyamjav Sumberzul, MD, PhDd, and Janet W. Rich-Edwards, ScDb,c,g
A Massachusetts General Hospital, Boston, Massachusetts;
B Harvard Medical School, Boston, Massachusetts;
C Harvard School of Public Health, Boston, Massachusetts;
D Health Sciences University of Mongolia, Ulaanbaatar, Mongolia;
E Dana Farber Cancer Institute, Boston, Massachusetts;
F Harvard Pilgrim Health Care Institute, Boston, Massachusetts; and
G Brigham and Women’s Hospital, Boston, Massachusetts

OBJECTIVE: Observational studies suggest that serum levels of 25-hydroxyvitamin D (25[OH]D) are inversely associated with acute respiratory tract infections (ARIs). We hypothesized that vitamin D supplementation of children with vitamin D deficiency would lower the risk of ARIs.

METHODS: By using cluster randomization, classrooms of 744 Mongolian schoolchildren were randomly assigned to different treatments in winter (January–March). This analysis focused on a subset of 247 children who were assigned to daily ingestion of unfortified regular milk (control; n = 104) or milk fortified with 300 IU of vitamin D3 (n = 143). This comparison was double-blinded. The primary outcome was the number of parent-reported ARIs over the past 3 months.

RESULTS: At baseline, the median serum 25(OH)D level was 7 ng/mL (interquartile range: 5–10 ng/mL). At the end of the trial, follow-up was 99% (n = 244), and the median 25(OH)D levels of children in the control versus vitamin D groups was significantly different (7 vs 19 ng/mL; P < .001).

Compared with controls, children receiving vitamin D reported significantly fewer ARIs during the study period (mean: 0.80 vs 0.45; P = .047), with a rate ratio of 0.52 (95% confidence interval: 0.31–0.89).

Adjusting for age, gender, and history of wheezing, vitamin D continued to halve the risk of ARI (rate ratio: 0.50 [95% confidence interval: 0.28–0.88]). Similar results were found among children either below or above the median 25(OH)D level at baseline (rate ratio: 0.41 vs 0.57; Pinteraction = .27).

CONCLUSIONS: Vitamin D supplementation significantly reduced the risk of ARIs in winter among Mongolian children with vitamin D deficiency.
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3 months RCT
Both trial and control drank milk in the winter
Trial: 300 IU ; Control: 0 IU
7ng ==> 17 ng

See also VitaminDWiki