Methods	Design: RCT
	Unit of randomisation: Indivdually randomised trial
Participants	Location/Setting: Schools in urban Beijing, China
	Sample size: 757 adolescent girls
	Dropouts/withdrawals: 59/757 loss to follow‐up
	Sex: Only adolescent girls
	Mean age: 10 (0.03) years
	Inclusion criteria: Healthy girls aged 10 years
	Exclusion criteria: Not specified
Interventions	Intervention (sample size):
	Group 1 (N = 238): Girls consumed a carton of 330 ml milk fortified with Ca on school days over the study period
	Group 2 (N = 260): Girls received the same quantity of milk additionally fortified with 5 or 8 mg cholecalciferol
	The duration of intervention was 24 months
	Control (sample size):
	Group 3 (N = 259): Control girls did not receive any intervention
Outcomes	Primary outcomes: Nutrient intake, bone mineral content, bone mineral density, serum PTH, serum calcium, height, weight and vitamin D levels
	Secondary outcomes: Not specified
	Timing of outcome assessment: Immediately after the 24 months of intervention and 3 years post intervention
Notes	Study start date: April 1999
	Study end date: March 2001
	Funding source: Australian Dairy Research and Development Corporation, Murray Goulburn Co‐operative Co. Limited (formulated and produced the milk supplements) and the Nestle' Foundation provided financial support for the laboratory analyses
	Conflicts of interest: None declared