Gillman 1995.

Study characteristics
Methods	Randomised, double‐blind, placebo‐controlled trial The trial was conducted in the United States of America.
Participants	101 5th‐grade students Gender: 50 girls and 51 boys Ethnicity: 61 were black. Setting: inner city school
Interventions	Intervention: 480 mL of juice containing 600 mg calcium (as calcium citrate malate) daily Control: Same juice with no calcium Trial duration: 12 weeks
Outcomes	"Blood pressure 4 times on each of 3 weekly sittings at baseline and at follow‐up"
Notes	Nutrient data from 3 sets of 2‐day food records on each participant Funding: Procter and Gamble Co
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Random allocation was performed by a centralised unit with the ID numbers that researchers provided. ID labels were affixed to each 'juice box', and sent to researchers who were completely blinded to treatment assignment.
Allocation concealment (selection bias)	Low risk	Random allocation was performed by a centralised unit with the ID numbers that researchers provided. ID labels were affixed to each 'juice box' and sent to researchers who were completely blinded to treatment assignment.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	All investigators and participants were masked to treatment assignment throughout the intervention period. "The intervention and placebo beverages were formulated to look and taste the same". "Single‐serving containers ("juice boxes") and labelled with the subject's name and study identification number"
Blinding of outcome assessment (detection bias) All outcomes	Low risk	"Automated device (Dinamap Vital Signs Monitor model 845‐A, Critikon, Inc., Tampa, Fla.)". "Blood pressure data were automatically recorded on a floppy disk; investigators and participants were masked to these data until the end of the study".
Incomplete outcome data (attrition bias) All outcomes	Low risk	106 participants randomised, 5 moved from the school and the analyses included 101 participants. Age, sex, and race of non‐participants and those who dropped out before intervention were similar.
Selective reporting (reporting bias)	Low risk	All outcomes were reported.
Other bias	Low risk	There were small differences (in different directions) between intervention and placebo participants in baseline systolic blood pressure, hours of television watched, and amount of dietary calcium.