Reference | Latitude | Vitamin D Daily Dosage (IU) | Weeks | Vitamin D Supplementationa | Placeboa | ||||||
---|---|---|---|---|---|---|---|---|---|---|---|
N | Pre | Post | Change | N | Pre | Post | Change | ||||
Insufficient vitamin D (N = 92) |  |  |  |  |  |  |  |  |  | ||
Winter (N = 92) |  |  |  |  |  |  |  |  |  | ||
 Jung 2018 [30] | < 45° N | 5000 | 4 | 20 | 10.9 ± 0.5 | 38.4 ± 1.5 | 17.5 | 15 | 12.4 ± 0.8 | 13.1 ± 1.0 | 0.7 |
 Close 2013b [32] | ≥45° N | 5000 | 6 | 5 | 11.6 ± 10.0 | 41.3 ± 10.0 | 29.7 | 5 | 21.2 ± 11.6 | 29.6 ± 9.6 | 8.4 |
 bClose 2013a [28] | ≥45° N | 5714 | 12 | 6 | 20.4 ± 10.4 | 36.5 ± 9.6 | 16.1 | 9^ | 20.8 ± 10.8 | 16.4 ± 8.8 | −4.4 |
 bClose 2013a [28] | ≥45° N | 2857 | 12 | 10 | 21.2 ± 10.4 | 34.1 ± 4.0 | 12.9 | 9^ | 20.8 ± 10.8 | 16.4 ± 8.8 | − 4.4 |
 Wyon 2016 [29] | ≥45° N | 18,750 | 1 | 11 | 13.2 ± 3.8 | 16.8 ± 3.2 | 3.6 | 11 | 16.3 ± 2.7 | 16.3 ± 2.6 | 0 |
Sufficient vitamin D (N = 57) |  |  |  |  |  |  |  |  |  | ||
Autumn (N = 57) |  |  |  |  |  |  |  |  |  | ||
 Fairbairn 2018 [31] | ≥45° S | 3570 | 12 | 28 | 37.2 ± 7.6 | 44.4 ± 7.2 | 7.2 | 29 | 38 ± 6.8 | 34 ± 6.8 | −4 |