Davis 1996.

Study characteristics
Methods	Randomised controlled trial The trial was conducted in the United States of America.
Participants	34 healthy, normotensive adolescents Ethnicity: African‐American Age:14‐19 years
Interventions	Intervention: 1.5 grams of calcium per day Control group: daily placebo tablets Trial duration: 4 weeks
Outcomes	Ambulatory systolic blood pressure and diastolic blood pressure
Notes	There was no information on calcium intake reported. Participants were recruited from a high school in Los Angeles.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	The authors reported that participants were randomly assigned to the treatment or control group.
Allocation concealment (selection bias)	Unclear risk	Not described
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Not described
Blinding of outcome assessment (detection bias) All outcomes	Low risk	The ambulatory blood pressure unit measured the blood pressure every 30 minutes during the day. "Unit was placed on each participant for 24 hours".
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Not reported how many participants gave data for the results
Selective reporting (reporting bias)	Low risk	The planned outcome was reported.
Other bias	Unclear risk	No information on baseline characteristics was reported.