Table 2.

Serum levels of 25-hydroxyvitamin D in randomized trials with Vitamin D supplements

Trial	Mean serum 25-hydroxyvitamin D3 (nmol/L)
	Intervention group		Control group
	Initial levels	Achieved levels	Initial levels	Achieved levels
Ljunghall et al. (1987)	75.5	85.7	79.6	110.2
Pfeifer et al. (2001)	25.65	64.84	24.63	44.36
Nagpal et al. (2009)	36.5	71.6	30.0	30.6
Zittermann et al. (2009)	30.0	85.5	30.3	42.0
Jorde et al. (a). (2010)	56.7	99.5	58.8	57.2
Jorde et al. (b). (2010)	58.7	138.0	58.8	57.2
Witham et al. (a). (2010)	41.0	63.0	45.0	54.0
Witham et al. (b). (2010)	48.0	79.0	45.0	54.0
Witham et al. (2010)	38.7	51.0	37.8	40.0
Maki et al. (2011)	64.4	76.1	67.9	66.7