Randomised controlled trials of vitamin D3 supplementation in preschool and school-age children with asthma
| Study | Study type | Study population | Age, years | Baseline 25(OH)D, nmol·L−1 | Oral dose of vitamin D3 (intervention arm) | Outcome |
| Urashima et al. [17] | Randomised controlled trial | School-age children with asthma | 9.5 (2.1; 6.0–15.0) | Not determined | 1200 IU·day−1 | Significant preventive effect against influenza A LRTIs |
| Majak et al. [18] | Randomised controlled trial with a cohort design | School-age children with asthma | 10.9 (3.3; 6.0–17.0) | 88.9 (38.2; 31.5–184.7) | 500 IU·day−1 | Reduced the number of asthma exacerbations triggered by acute respiratory tract infection during 6 months of follow-up |
| Tachimoto et al. [19] | Randomised controlled trial with a cohort design | School-age children with asthma | 9.9 (2.3; 6.0–15.0) | 74.9 (24.6; 20.0–187.2) | 800 IU·day−1 | Improved ACT at 6 months of follow-up |
| Jensen et al. [20] | Randomised controlled trial with a cohort design | Preschool children with recurrent wheeze | 2.9 (1.1; 1.6–5.5) | 64.2 (14.0; 42·0–87·0) | 100 000 IU bolus plus 400 IU·day−1 | No effect on use of oral corticosteroids during 6 months of follow-up |
| Kerley et al. [21] | Randomised controlled trial with a cohort design | School-age children with asthma | 8.6 (2.8; 5.0–15.0) | 54.4 (17.4; 26.0–92.0) | 2000 IU·day−1 | No significant difference in asthma control during 4 months of follow-up |
| Jat et al. [15] | Randomised controlled trial with a cohort design | Preschool and school-age children with asthma | 8.1 (2.3; 4.0–12.0) | 18.6 (4.1; 21.7–32.9) | 1000 IU·day−1 | No significant difference in asthma control and in the number of asthma exacerbations during 9 months of follow-up |
Data are presented as median (minimum; interquartile range), unless stated otherwise. 25(OH)D: 25-hydroxyvitamin D; LRTI: lower respiratory tract infection; ACT: asthma control test.