| Methods | Double‐blind, placebo‐controlled trial. Participants were assigned to 2 groups according to a randomised block design that accounted for habitual calcium intake and BMI. The trial was conducted in the Netherlands. |
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| Participants | 58 normotensive healthy female dietetic students, not receiving any medical treatment at the time of recruitment. Age: 20 ‐ 23 year. Weight:49 ‐ 76 kg. |
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| Interventions | Intervention group: Daily lemonade or apple juice with powder containing 1500 mg Calcium ‐ calcium carbonate (1. 251 g), citric acid (2. 168 g), sodium‐hydrogen carbonate (0.5 g), and dextrose (2.88 g). Control group: Daily lemonade or apple juice placebo powder with citric acid (0.85 g), sodium‐hydrogen carbonate (0.5 g), dextrose (4.5 g), and corn‐flour (0. 1 g). Both groups received a low‐calcium diet (500 mg Calcium a day) restricting intake of dairy products. Trial duration: 6 weeks. |
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| Outcomes | Difference for each individual between baseline blood pressure and final blood pressure Individual change in blood pressure during the experiment as indicated by the regression coefficient (slope) obtained from linear regression analysis of blood pressure versus time during the experimental period |
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| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Participants were assigned to 2 groups according to a randomised block design that accounted for habitual calcium intake and body mass index. |
| Allocation concealment (selection bias) | Unclear risk | Not described |
| Blinding of participants and personnel (performance bias) All outcomes | Unclear risk | Double‐blind, placebo‐controlled trial but methods not described |
| Blinding of outcome assessment (detection bias) All outcomes | Unclear risk | Not described |
| Incomplete outcome data (attrition bias) All outcomes | Low risk | All participants were reported in the results |
| Selective reporting (reporting bias) | Low risk | All outcomes were reported. |
| Other bias | Low risk | Baseline characteristics were similar between the 2 groups. |
ABP: ambulatory blood pressure BMI: body mass index BP: blood pressure DBP: diastolic blood pressure HDL: high‐density lipids LDL: low‐density lipids SBP: systolic blood pressure SD: standard deviation