Table 3.
Supplementation protocols.
| Study | Circulating Vitamin D Levels (ng/mL) before the Study | Dose (IU) | Extent |
|---|---|---|---|
| Nieman et al., 2013 [32] | 39 ± 2 (Experimental group *) 43 ± 3 (Placebo group) |
3800 IU/day | 6 weeks |
| Shanely et al., 2014 [33] | 25 ± 2 (Experimental group *) 25 ± 2 (Placebo group) |
600 IU/day | 6 weeks |
| Parsaie et al., 2019 [34] | 14 (Experimental group *) 15 (Placebo group) |
50,000 IU/week | 8 weeks |
| Ashtary-Larky et al., 2020 [35] | 14 ± 3.9 (Experimental group *) 22 ± 5 (Placebo group) |
300,000 IU injected | 4 weeks |
| Pilch et al., 2020 [36] | 30.5 ± 0.34 (OE group: Optimal levels of vitamin D at the beginning and supplemented during the intervention) 36.16 ± 4.4 (OC group: Optimal levels of vitamin D at the beginning and no supplemented during the intervention) 19 ± 1 (SE group: Suboptimal levels of vitamin D at the beginning and supplemented during the intervention) 14 ± 5 (SC group: Suboptimal levels of vitamin D at the beginning and no supplemented during the intervencion) |
Calculated from participant’s body mass using Singh and Bonham formula. | 12 weeks |
| Żebrowska et al., 2020 [37] | 40 ± 8.8 (Experimental group *) 33.3 ± 3.4 (Placebo group) |
2000 IU/day | 3 weeks |
(*) The experimental groups consume the corresponding dose of vitamin D indicated in the next column (“Dose (IU)”). Abbreviations used: IU, international units.