The Editorial Executive Committee welcomes letters, which should be less than 250 words. Before a decision to publish is made, letters which refer to a published article may be sent to the author for a response. Any letter may be sent to an expert for comment. When letters are published, they are usually accompanied in the same issue by their responses or comments. The Committee screens out discourteous, inaccurate or libellous statements. The letters are sub-edited before publication. Authors are required to declare any conflicts of interest. The Committee's decision on publication is final.

Letter to the Editor

Editor, – I am writing in response to the recent article on calcium and cardiovascular risks by Mark Bolland, Andrew Grey and Ian Reid (Aust Prescr 2013;36:5-8 ).

I would like to address their statement that ‘A more recent randomised controlled trial of sunlight exposure to raise vitamin D concentrations in Australian nursing home residents also found that the addition of calcium supplements to sunlight exposure was associated with increases in all-cause and cardiovascular mortality’.1,2 The authors did not reveal that the assertion is based on comparisons between ultraviolet ray exposure only versus ultraviolet ray exposure plus calcium supplementation, and not to a control group. However, based on data analysis of death certificates within the study follow-up period, I do not see a significant difference between ultraviolet ray exposure plus calcium supplementation versus control group, hence it should be concluded that the former does not have increased cardiovascular mortality rates over the control population.

Shyan Goh
Locum orthopaedic registrar
Sydney

Authors' comments

Mark Bolland, Andrew Grey and Ian Reid, the authors of the article, comment:

The appropriate comparison to assess the effect of calcium is between the sunlight arm and the sunlight plus calcium arm, which only differ by use of calcium. This comparison showed increased all-cause and cardiovascular mortality in the sunlight plus calcium arm.

It is not surprising that our article challenges some readers because calcium has long been thought to be safe and effective. In 2005–06, five large randomised controlled trials were published on calcium with or without vitamin D in community-dwelling individuals with fracture as the primary end point.3-7 The trials provide a strong evidence base to inform clinical practice. None of them reported statistically significant reductions in fracture, but individual studies reported that calcium increased the risk of hip fracture, 7 cardiovascular events,7,8 kidney stones,5 and hospitalisation from gastrointestinal symptoms.6,9 Additionally, calcium was poorly tolerated (compliance approximately 50%). Meta-analyses confirmed these findings as discussed in our article.

Individually, concerns regarding the lack of efficacy, safety or poor tolerability of calcium supplements would provide a good reason for revisiting their role, but collectively these concerns provide a compelling argument against their widespread use. We think that dispassionate reviews of the evidence will lead to similar conclusions to ours, as shown by the US Preventive Services Task Force recently recommending against the use of calcium and vitamin D for primary fracture prevention.10

References

  1. Grey A. Calcium supplementation: balancing the cardiovascular risks. Maturitas 2011;69:289-95 .
  2. Sambrook PN, Cameron ID, Chen JS, Cumming RG, Durvasula S, Herrmann M. Does increased sunlight exposure work as a strategy to improve vitamin D status in the elderly: a cluster randomised controlled trial. Osteoporos Int 2011;23:615-24 .
  3. Grant AM, Campbell MK, McDonald AM, MacLennan GS, McPherson GC. Oral vitamin D3 and calcium for secondary prevention of low-trauma fractures in elderly people (Randomised Evaluation of Calcium Or vitamin D, RECORD): a randomised placebo-controlled trial. Lancet 2005;365:1621-8 .
  4. Porthouse J, Cockayne S, King C, Saxon L, Steele E, Aspray T. Randomised controlled trial of calcium and supplementation with cholecalciferol (vitamin D3) for prevention of fractures in primary care.BMJ 2005;330:1003. .
  5. Wallace RB, Robbins J, Lewis CE, Jackson RD, LaCroix AZ, Gass M. Calcium plus vitamin D supplementation and the risk of fractures. N Engl J Med 2006;354:669-83 .
  6. Devine A, Dhaliwal SS, Dick IM. Effects of calcium supplementation on clinical fracture and bone structure: results of a 5-year, double-blind, placebo-controlled trial in elderly women. Arch Intern Med 2006;166:869-75 .
  7. Reid IR, Reid HE, Bava U. Randomized controlled trial of calcium in healthy older women. Am J Med 2006;119:777-85 .
  8. Bolland MJ, Barber PA, Doughty RN, Mason B, Horne A, Ames R. Vascular events in healthy older women receiving calcium supplementation: randomised controlled trial. BMJ 2008;336:262-6 .
  9. Lewis JR, Zhu K. Adverse events from calcium supplementation: relationship to errors in myocardial infarction self-reporting in randomized controlled trials of calcium supplementation. J Bone Miner Res2012;27:719-22 .
  10. Moyer VA; U.S. Preventive Services Task Force. Vitamin D and calcium supplementation to prevent fractures in adults: U.S. Preventive Services Task Force recommendation statement. Ann Intern Med 2013;158:691-6 .