Effects of vitamin D3 supplementation on serum 25(OH)D concentration and strength in athletes: a systematic review and meta-analysis of randomized controlled trials

Table 3 Baseline and Follow-up Serum 25(OH)D concentrations

Reference	Latitude	Time	Vitamin D3 Daily Dosage	Baseline (ng/mL)	N = 149	1 Week (ng/mL)	4 Weeks (ng/mL)	6 Weeks (ng/mL)	8 Weeks (ng/mL)	12 Weeks (ng/mL)
Reference	Latitude	Time	IU	Baseline (ng/mL)	N = 149	1 Week (ng/mL)	4 Weeks (ng/mL)	6 Weeks (ng/mL)	8 Weeks (ng/mL)	12 Weeks (ng/mL)
Jung 2018 [30]	33.3° N	Jan–Feb	5000	10.9 ± 0.5	20		38.4 ± 1.5
Jung 2018 [30]	33.3° N	Jan–Feb	0	12.4 ± 0.8	15		13.1 ± 1.0
Fairbairn 2018 [31]	45–46.5° S	Mar–May	3570	37.2 ± 7.6	28			44.4 ± 7.2		45.6 ± 7.6
Fairbairn 2018 [31]	45–46.5° S	Mar–May	0	38 ± 6.8	29			34 ± 6.8		32 ± 8.4
Close 2013b [32]	53° N	Nov–Jan	5000	11.6 ± 10.0	5				41.3 ± 10.0
Close 2013b [32]	53° N	Nov–Jan	0	21.2 ± 11.6	5				29.6 ± 9.6
Close 2013a [28]	53° N	Jan–Apr	5714	20.4 ± 10.4	6			39.3 ± 5.6		36.5 ± 9.6
			2857	21.2 ± 10.4	10			31.7 ± 5.6		34.1 ± 4.0
			0	20.8 ± 10.8	9			14.8 ± 7.2		16.4 ± 8.8
Wyon 2016 [29]	52.3° N	Feb	18,750	13.2 ± 3.8	11	16.8 ± 3.2
Wyon 2016 [29]	52.3° N	Feb	0	16.3 ± 2.7	11	16.3 ± 2.6

Data are mean ± standard deviation unless stated otherwise. Measurements are in ng/mL

ISSN: 1550-2783