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Recommendations Summary

HTN: Calcium 2015

Click here to see the explanation of recommendation ratings (Strong, Fair, Weak, Consensus, Insufficient Evidence) and labels (Imperative or Conditional). To see more detail on the evidence from which the following recommendations were drawn, use the hyperlinks in the Supporting Evidence Section below.


  • Recommendation(s)

    HTN: Dietary Calcium

    The registered dietitian nutritionist (RDN) should encourage adults with hypertension (HTN) to consume adequate amounts of dietary calcium to meet the dietary reference intakes (DRI) to aid in blood pressure (BP) control. Research indicates that dietary calcium intake of 800mg or more per day reduced systolic blood pressure (SBP) up to 4mm Hg and diastolic blood pressure (DBP) up to 2mm Hg in adults with HTN. 

    Rating: Fair
    Imperative

    HTN: Calcium Supplements

    If an adult with HTN is unable to meet the DRI for calcium with diet and food alone, the RDN may consider recommending calcium supplementation of 1, 000mg to 1, 500mg per day to aid in BP control. A strong body of research indicates that calcium supplementation of 1, 000mg to 1, 500mg per day reduced SBP up to 3.0mm Hg and DBP up to 2.5mm Hg in adults with HTN. 

    Rating: Strong
    Conditional

    • Risks/Harms of Implementing This Recommendation

      • In healthy people, excess calcium intake from food is rare; excess intake from calcium supplements are more likely (Office of Dietary Supplements)
      • When taking calcium supplements, individuals should not exceed the tolerable upper intake level (UL) for calcium (2, 500mg or more for ages 18 years to 50 years or 2, 000mg for 51 years or older). Exeeding the UL for calcium may be associated with (Office of Dietary Supplements):
        • Excessively high levels of calcium in the blood (known as hypercalcemia) that may cause renal insufficiency, vascular and soft tissue calcification, hypercalciuria (high levels of calcium in the urine) and kidney stones
        • Constipation
        • Interference with the absorption of iron and zinc
        • Increased risk of kidney stones 
        • Increased risk of prostate cancer and cardiovascular disease. 

    • Conditions of Application

      • The HTN: Calcium Supplements recommendation applies only to individuals with HTN who are unable to meet the DRI for calcium with food intake alone
      • The RDN should consider all sources of dietary calcium, including foods and beverages fortified with calcium
      • The RDN should also consider intake of calcium from over-the-counter antacids containing calcium carbonate (e.g., Tums, Rolaids) (Office of Dietary Supplements).

    • Potential Costs Associated with Application

      If an individual is unable to meet the DRI for dietary calcium, there is an additional cost for calcium supplements.

    • Recommendation Narrative

      A total of eight studies were included in the evidence analysis supporting the recommendations:

      • One positive quality meta-analysis (Dickinson et al, 2006) 
      • Two positive quality cross-sectional studies (Schroder et al, 2002; Varenna et al, 2013)
      • One positive quality prospective cohort study (Toledo et al, 2009) 
      • One neutral quality meta-analysis (van Mierlo et al, 2006) 
      • One neutral quality randomized controlled trial (RCT) (Pikilidou et al, 2009)
      • One neutral quality randomized crossover trial (Hilpert et al, 2009)
      • One neutral quality cross-sectional study (Lancaster et al, 2004).
      Dietary Calcium 
      • Six studies were included in the evidence analysis: Hilpert et al, 2009; Lancaster et al, 2004; Schroder et al, 2002; Toledo et al, 2009; van Mierlo et al, 2006; Varenna et al, 2013
      • In four of six studies of adults with HTN, total dietary calcium intake of 800mg or more per day (primarily from dairy products), reduced SBP up to 4mm Hg and DBP up to 2mm Hg (Hilpert et al, 2009; Schroder et al, 2002; Toledo et al, 2009; Varenna et al, 2013)
      • Two studies did not find relationships between calcium intake and BP in HTN (Lancaster et al, 2004; van Mierlo et al, 2006).
      Calcium Supplementation 
      • Three studies were included in the evidence analysis: Dickinson et al, 2006; Pikilidou et al, 2009; van Mierlo et al, 2006
      • In two meta-analyses [representing 38 randomized controlled trials (RCTs)] of adults with hypertension, calcium supplementation of 1, 000mg to 1, 500mg per day reduced systolic blood pressure up to 3.0mm Hg and diastolic blood pressure up to 2.5mm Hg (Dickinson et al, 2006; van Mierlo et al, 2006)
      • One study did not find significant effects on blood pressure with calcium supplementation (Pikildou et al, 2009).

    • Recommendation Strength Rationale

      • Conclusion statement for Dietary Calcium is Grade II
      • Conclusion statement for Calcium Supplements is Grade I.

    • Minority Opinions

      None.