Osteoporosis International

, Volume 22, Issue 12, pp 3073–3077

The calcium scare—what would Austin Bradford Hill have thought?

  • B. E. C. Nordin
  • J. R. Lewis
  • R. M. Daly
  • J. Horowitz
  • A. Metcalfe
  • K. Lange
  • R. L. Prince
Short Communication

DOI: 10.1007/s00198-011-1680-4

Cite this article as:
Nordin, B.E.C., Lewis, J.R., Daly, R.M. et al. Osteoporos Int (2011) 22: 3073. doi:10.1007/s00198-011-1680-4

Abstract

Summary

Detailed consideration of the suggested association between calcium supplementation and heart attacks has revealed weakness in the evidence which make the hypothesis highly implausible.

Introduction

The aim of this study was to evaluate the strength of the evidence that calcium supplementation increases the risk of myocardial infarction.

Methods

This study used critical examination of a meta-analysis of the effects of calcium supplements on heart attacks in five prospective trials on 8,016 men and women, and consideration of related publications by the same author.

Results

The meta-analysis was found to be subject to several limitations including non-adherence to the clinical protocol, multiple endpoint testing and failure to correctly adjust for endpoint ascertainment. The main risk factors for myocardial infarction were not available for 65% of the participants, and none of the trials had cardiovascular disease as its primary endpoint. There were more overweight participants, more subjects on thyroxine and more men on calcium than on placebo. In particular, over 65% of all the heart attacks were self-reported. When the evidence was considered in the light of Austin Bradford Hill's six main criteria for disease causation, it was found not to be biologically plausible or strong or to reflect a dose–response relationship or to be consistent or to reflect the relationship between the trends in calcium supplementation and heart attacks in the community or to have been confirmed by experiment. The addition of a more recent trial on 1,460 women over 5 years reduced the relative risk to 1.23 (P = 0.0695).

Conclusion

Present evidence that calcium supplementation increases heart attacks is too weak to justify a change in prescribing habits.

Keywords

Calcium supplements Cardiovascular disease Myocardial infarction 

Copyright information

© International Osteoporosis Foundation and National Osteoporosis Foundation 2011

Authors and Affiliations

  • B. E. C. Nordin
    • 1
  • J. R. Lewis
    • 2
  • R. M. Daly
    • 3
  • J. Horowitz
    • 4
  • A. Metcalfe
    • 5
  • K. Lange
    • 6
  • R. L. Prince
    • 7
  1. 1.Endocrine and Metabolic UnitRoyal Adelaide HospitalAdelaideAustralia
  2. 2.Department of Endocrinology and DiabetesSir Charles Gairdner HospitalNedlandsAustralia
  3. 3.School of Exercise and Nutrition SciencesDeakin UniversityBurwoodAustralia
  4. 4.Cardiology UnitUniversity of AdelaideAdelaideAustralia
  5. 5.School of Mathematical SciencesUniversity of AdelaideAdelaideAustralia
  6. 6.Discipline of MedicineUniversity of AdelaideAdelaideAustralia
  7. 7.School of Medicine and PharmacologyUniversity of Western AustraliaCrawleyAustralia

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