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Review
, 2015 (6), CD010037

Calcium Supplementation for Prevention of Primary Hypertension

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Review

Calcium Supplementation for Prevention of Primary Hypertension

Gabriela Cormick et al. Cochrane Database Syst Rev.

Abstract

Background: Hypertension is a major public health problem that increases the risk of cardiovascular and kidney diseases. Several studies have shown an inverse association between calcium intake and blood pressure. As small reductions in blood pressure have been shown to produce rapid reductions in vascular disease risk even in individuals with normal blood pressure ranges, this review intends to evaluate the effect of calcium supplementation in normotensive individuals as a preventive health measure.

Objectives: To assess the efficacy and safety of calcium supplementation versus placebo or control for reducing blood pressure in normotensive people.

Search methods: We searched the Cochrane Hypertension Group Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, MEDLINE In-Process, EMBASE and ClinicalTrials.gov for randomised controlled trials up to October 2014. The WHO International Clinical Trials Registry Platform (ICTRP) is searched for inclusion in the Group's Specialised Register. We also reviewed reference lists from retrieved studies and contacted authors of relevant papers. We applied no language restrictions.

Selection criteria: We selected trials that randomised normotensive people to dietary calcium interventions such as supplementation or food fortification versus placebo or control. We excluded quasi-random designs. The primary outcomes were hypertension (defined as blood pressure ≥ 140/90 mmHg) and blood pressure measures.

Data collection and analysis: Two review authors independently selected trials for inclusion, abstracted the data and assessed the risks of bias.

Main results: We included 16 trials with 3048 participants. None of the studies reported hypertension as a dichotomous outcome. The effect on systolic and diastolic blood pressure was mean difference (MD) -1.43 mmHg (95% confidence interval (CI) -2.15 to -0.72) and -0.98 mmHg (95%CI -1.46 to -0.50) respectively. The effect on systolic and diastolic blood pressure for those younger than 35 years (7 trials with 399 participants) was -2.11 mmHg (95%CI -3.58 to -0.64) / -2.61 mmHg (95% CI -3.74, -1.49). The effect on systolic and diastolic blood pressure for those 35 years or more (9 trials with 2649 participants) was -0.96 mmHg (95%CI -1.83 to -0.09) / -0.59 mmHg (95%CI -1.13 to -0.06). The effect on systolic and diastolic blood pressure for women (6 trials with 1823 participants) was -1.45 mmHg (95% CI -2.78 to -0.12) / -0.92 mmHg (95% CI -1.71 to -0.14). The effect on systolic and diastolic blood pressure for men (5 trials with 617 participants) was -2.07 (95%CI -3.56 to -0.59] / -1.91 (95%CI -2.80 to -1.02).The quality of evidence for each of these outcomes was high. The effect is consistent in both genders regardless of baseline calcium intake.The effect on systolic blood pressure was 0.08 mmHg (95% CI -2.16 to 2.32) with doses less than 1000 mg, -1.14 mmHg (95% CI -2.01 to -0.27) with 1000 - 1500 mg, and -2.79 mmHg (95% CI -4.71 to -0.86) with more than 1500 mg. The effect on diastolic blood pressure was -0.54 mmHg (95% CI -2.23 to 1.15), -0.71 mmHg (95% CI -1.37 to -0.06) and -1.43 mmHg (95% CI -2.22 to -0.64) respectively. The quality of evidence for each of these outcomes was high.None of the studies reported adverse events.

Authors' conclusions: An increase in calcium intake slightly reduces both systolic and diastolic blood pressure in normotensive people, particularly in young people, suggesting a role in the prevention of hypertension. These results should be interpreted with caution, since the proposed biological mechanism explaining the relationship between calcium and blood pressure has not been fully confirmed. The effect across multiple prespecified subgroups and a possible dose response effect reinforce this conclusion. Even small reductions in blood pressure could have important health implications for reducing vascular disease.There is a great need for adequately-powered clinical trials randomising young people. Subgroup analysis should involve basal calcium intake, age, sex, basal blood pressure, and body mass index. We also require assessment of side effects, optimal doses and the best strategy to improve calcium intake.

Conflict of interest statement

Gabriela Cormick: Nothing to declare.

Agustín Ciapponi: Nothing to declare.

María Luisa Cafferata: Nothing to declare.

José M Belizán: Nothing to declare.

Figures

Figure 1
Figure 1
Study flow diagram.
Figure 2
Figure 2
Risk of bias summary: review authors' judgements about each risk of bias item for each included study.
Figure 3
Figure 3
Risk of bias graph: review authors' judgements about each risk of bias item presented as percentages across all included studies.
Figure 4
Figure 4
Funnel plot of comparison: 1 Calcium supplementation/fortification vs control, outcome: 1.1 Effect mean difference of systolic blood pressure.
Figure 5
Figure 5
Funnel plot of comparison: 1 calcium supplementation/fortification vs control, Effect Mean difference of Diastolic blood pressure.
Analysis 1.1
Analysis 1.1
Comparison 1 Calcium supplementation/fortification vs control, Outcome 1 Effect mean difference of systolic blood pressure.
Analysis 1.2
Analysis 1.2
Comparison 1 Calcium supplementation/fortification vs control, Outcome 2 Effect mean difference of diastolic blood pressure.
Analysis 1.3
Analysis 1.3
Comparison 1 Calcium supplementation/fortification vs control, Outcome 3 Change of systolic blood pressure.
Analysis 1.4
Analysis 1.4
Comparison 1 Calcium supplementation/fortification vs control, Outcome 4 Change of diastolic blood pressure.
Analysis 1.5
Analysis 1.5
Comparison 1 Calcium supplementation/fortification vs control, Outcome 5 Final value of systolic blood pressure.
Analysis 1.6
Analysis 1.6
Comparison 1 Calcium supplementation/fortification vs control, Outcome 6 Final value of diastolic blood pressure.
Analysis 1.7
Analysis 1.7
Comparison 1 Calcium supplementation/fortification vs control, Outcome 7 Effect mean difference of systolic blood pressure by age.
Analysis 1.8
Analysis 1.8
Comparison 1 Calcium supplementation/fortification vs control, Outcome 8 Effect mean difference of diastolic blood pressure by age.
Analysis 1.9
Analysis 1.9
Comparison 1 Calcium supplementation/fortification vs control, Outcome 9 Change in systolic blood pressure by age.
Analysis 1.10
Analysis 1.10
Comparison 1 Calcium supplementation/fortification vs control, Outcome 10 Change in diastolic blood pressure by age.
Analysis 1.11
Analysis 1.11
Comparison 1 Calcium supplementation/fortification vs control, Outcome 11 Final value in systolic blood pressure by age.
Analysis 1.12
Analysis 1.12
Comparison 1 Calcium supplementation/fortification vs control, Outcome 12 Final value in diastolic blood pressure by age.
Analysis 1.13
Analysis 1.13
Comparison 1 Calcium supplementation/fortification vs control, Outcome 13 Effect mean difference in systolic blood pressure by basal calcium intake.
Analysis 1.14
Analysis 1.14
Comparison 1 Calcium supplementation/fortification vs control, Outcome 14 Effect mean difference in diastolic blood pressure by basal calcium intake.
Analysis 1.15
Analysis 1.15
Comparison 1 Calcium supplementation/fortification vs control, Outcome 15 Change in systolic blood pressure by basal calcium intake.
Analysis 1.16
Analysis 1.16
Comparison 1 Calcium supplementation/fortification vs control, Outcome 16 Change in diastolic blood pressure by basal calcium intake.
Analysis 1.17
Analysis 1.17
Comparison 1 Calcium supplementation/fortification vs control, Outcome 17 Final value of systolic blood pressure by basal calcium intake.
Analysis 1.18
Analysis 1.18
Comparison 1 Calcium supplementation/fortification vs control, Outcome 18 Final value of diastolic blood pressure by basal calcium intake.
Analysis 1.19
Analysis 1.19
Comparison 1 Calcium supplementation/fortification vs control, Outcome 19 Effect mean difference of systolic blood pressure by dose.
Analysis 1.20
Analysis 1.20
Comparison 1 Calcium supplementation/fortification vs control, Outcome 20 Effect mean difference of diastolic blood pressure by dose.
Analysis 1.21
Analysis 1.21
Comparison 1 Calcium supplementation/fortification vs control, Outcome 21 Change in diastolic blood pressure by dose.
Analysis 1.22
Analysis 1.22
Comparison 1 Calcium supplementation/fortification vs control, Outcome 22 Change in systolic blood pressure by dose.
Analysis 1.23
Analysis 1.23
Comparison 1 Calcium supplementation/fortification vs control, Outcome 23 Final value in systolic blood pressure by dose.
Analysis 1.24
Analysis 1.24
Comparison 1 Calcium supplementation/fortification vs control, Outcome 24 Final value in diastolic blood pressure by dose.
Analysis 1.25
Analysis 1.25
Comparison 1 Calcium supplementation/fortification vs control, Outcome 25 Effect mean difference of systolic blood pressure by duration.
Analysis 1.26
Analysis 1.26
Comparison 1 Calcium supplementation/fortification vs control, Outcome 26 Effect mean difference of diastolic blood pressure by duration.
Analysis 1.27
Analysis 1.27
Comparison 1 Calcium supplementation/fortification vs control, Outcome 27 Effect mean difference of systolic blood pressure by intervention type.
Analysis 1.28
Analysis 1.28
Comparison 1 Calcium supplementation/fortification vs control, Outcome 28 Effect mean difference of diastolic blood pressure by intervention type.

Update of

  • Cochrane Database Syst Rev. doi: 10.1002/14651858.CD010037

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