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Calcium-Only Supplements may Cause Myocardial Infarction

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	Staff Writer articles by this author...
Editing and Researching news and stories about global and local Pharmacy Issues

A recent New Zealand study relating to calcium supplements has been published in the British Medical Journal. The results suggest that for people over 40 years of age there is a 30% higher risk of myocardial infarction if they are taking straight calcium supplements in the 1000 mg range daily. The risk is identified and noted as a ”modest increase in the risk of myocardial infarction” by the researchers. However, pharmacists need to check if any of their cardiac patients are taking calcium supplements, and if so, what dosage and combination with other nutrients is being taken (if any). The following is an abstract of the study:

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Effect of calcium supplements on risk of myocardial infarction and cardiovascular events: meta-analysis

Mark J Bolland, senior research fellow¹, Alison Avenell, clinical senior lecturer², John A Baron, professor³, Andrew Grey, associate professor¹, Graeme S MacLennan, senior research fellow², Greg D Gamble, research fellow¹, Ian R Reid, professor¹

¹ Department of Medicine, Faculty of Medical and Health Sciences, University of Auckland, Private Bag 92 019, Auckland 1142, New Zealand, ² Health Services Research Unit, University of Aberdeen, ³ Department of Medicine, and Department of Community and Family Medicine, Dartmouth Medical School, NH, USA

Correspondence to: I R Reid i.reid@auckland.ac.nz

Abstract

Objective To investigate whether calcium supplements increase the risk of cardiovascular events.

Design Patient level and trial level meta-analyses.

Data sources Medline, Embase, and Cochrane Central Register of Controlled Trials (1966-March 2010), reference lists of meta-analyses of calcium supplements, and two clinical trial registries. Initial searches were carried out in November 2007, with electronic database searches repeated in March 2010.

Study selection Eligible studies were randomised, placebo controlled trials of calcium supplements (500 mg/day), with 100 or more participants of mean age more than 40 years and study duration more than one year. The lead authors of eligible trials supplied data. Cardiovascular outcomes were obtained from self reports, hospital admissions, and death certificates.

Results 15 trials were eligible for inclusion, five with patient level data (8151 participants, median follow-up 3.6 years, interquartile range 2.7-4.3 years) and 11 with trial level data (11 921 participants, mean duration 4.0 years). In the five studies contributing patient level data, 143 people allocated to calcium had a myocardial infarction compared with 111 allocated to placebo (hazard ratio 1.31, 95% confidence interval 1.02 to 1.67, P=0.035). Non-significant increases occurred in the incidence of stroke (1.20, 0.96 to 1.50, P=0.11), the composite end point of myocardial infarction, stroke, or sudden death (1.18, 1.00 to 1.39, P=0.057), and death (1.09, 0.96 to 1.23, P=0.18). The meta-analysis of trial level data showed similar results: 296 people had a myocardial infarction (166 allocated to calcium, 130 to placebo), with an increased incidence of myocardial infarction in those allocated to calcium (pooled relative risk 1.27, 95% confidence interval 1.01 to 1.59, P=0.038).

Conclusions Calcium supplements (without coadministered vitamin D) are associated with an increased risk of myocardial infarction. As calcium supplements are widely used these modest increases in risk of cardiovascular disease might translate into a large burden of disease in the population. A reassessment of the role of calcium supplements in the management of osteoporosis is warranted.

The Australian Self Medication Industry (ASMI) has responded with a statement that follows:

Calcium supplements and cardiovascular events

The Australian Self Medication Industry (ASMI), the industry body representing non-prescription consumer healthcare products said today that consumers should not be alarmed by recent media coverage linking calcium supplements with an increased risk of heart disease and should seek advice from their healthcare professional if they are concerned about their use of these products.

ASMI was responding to media coverage regarding the safety of calcium supplements following the publication of a recent article by Bolland et al in the British Medical Journal [1].
The article by Bolland suggested that the role of calcium supplements should be reassessed because they could increase a person’s risks of heart disease.

ASMI Regulatory and Scientific Affairs Director, Steven Scarff said that there was good evidence that calcium supplements reduced the risk of fractures and hence played a useful role in the treatment of osteoporosis [2, 3], and that the association with heart disease was controversial [4].

Mr Scarff also said that, in contrast to the Bolland study, other recent studies had failed to find a relationship between calcium supplements and increased cardiovascular risk [5, 6, 7] or had in fact ruled out such a relationship [8].

Mr Scarff said that consumers should continue to aim for the recommended daily calcium intake of 1000-1300mg/day (depending on their age and sex [9]) and that they should do this through eating a healthy diet or from supplements where their dietary intake was inadequate.

References

[1] Bolland MJ, Avenell A, Baron JA, Grey A, Maclennan GS, Gamble GD, Reid IR. Effect of calcium supplements on risk of myocardial infarction and cardiovascular events: meta-analysis. BMJ. 2010 Jul 29;341:c3691. doi: 10.1136/bmj.c3691.

[2] Tang BM, Eslick GD, Nowson C, Smith C, Bensoussan A. Use of calcium or calcium in combination with vitamin D supplementation to prevent fractures and bone loss in people aged 50 years and older: a meta-analysis. Lancet. 2007 Aug 25;370(9588):657-66.

[3] Osteoporosis Australia web-site. Calcium Supplements and heart Disease. www.osteoporosis.org.au

[4] Gustavo Duque, Jacqueline J Close, Julien P de Jager, Peter R Ebeling, Charles Inderjeeth, Stephen Lord, Andrew J McLachlan, Ian R Reid, Bruce R Troen and Philip N Sambrook. Treatment for osteoporosis in Australian residential aged care facilities: consensus recommendations for fracture prevention. MJA 2010; 193 (3): 173-179

[5] Chung M, Balk EM, Brendel M, Ip S, Lau J, Lee J, Lichtenstein A, Patel K, Raman G, Tatsioni A, Terasawa T, Trikalinos TA. Vitamin D and calcium: a systematic review of health outcomes, Evid Rep Technol Assess (Full Rep). 2009 Aug;(183):1-420. Review.

[6]Wang L, Manson JE, Song Y, Sesso HD. Systematic review: Vitamin D and calcium supplementation in prevention of cardiovascular events. Ann Intern Med. 2010 Mar 2;152(5):315-23. Review.

[7] Sabbagh Z, Vatanparast H. Is calcium supplementation a risk factor for cardiovascular diseases in older women? Nutr Rev. 2009 Feb;67(2):105-8.

[8] Lewis JR, Calver J, Zhu K, Flicker L, Prince RL. Calcium supplementation and the risks of atherosclerotic vascular disease in older women: results of a 5-year RCT and a 4.5-year follow-up. J Bone Miner Res. 2010 Jul 7. [Epub ahead of print]

[9] Australian Government, DOHA, NHMRC Recommended Dietary Intakes

i2P staff researchers performed a quick literature search to identify any further information that could support any recommendations made by pharmacists to their patients.

* New Zealand scientists analyzed 11 studies of nearly 12,000 people. They found that people over 40 who took high-dose calcium pills had a 30 percent higher risk of a heart attack than those who didn't. Some changes should be recommended here.

* Eating calcium-rich foods like cheese and milk did not raise risk, according to their study in the British Medical Journal in July. In fact, various studies have shown people who ate the most calcium-rich foods had the lowest risks of heart disease.

* A Korean study found that women who took in less calcium had a higher risk of metabolic syndrome, a risk for heart disease. So calcium-only supplements, not calcium-rich foods, might be the problem.

* The New Zealand researchers state it's not worth the risk to take calcium-only tablets, containing 500 milligrams of calcium or more, as they reduce the risk of broken bones by only 10 percent. Meanwhile, calcium-only supplements raise blood calcium levels, which may cause calcium deposits in the arteries and veins. Supplement combinations with Vitamin D3 and Vitamin K2 would be safer and could virtually eliminate risk.

* The New Zealanders excluded people who used calcium combined with vitamin D3 and other nutrients. That's ironic, because many physicians don't recommend calcium alone anymore--it's long been recommended with vitamin D3.

* The New Zealand research did not apply to multivitamin-mineral combinations.
That's because most daily supplements contain very little calcium, usually 200 milligrams or less. So there's no need to throw out the multivitamins.

* Taking vitamin D with calcium seems to be safe for the heart. Recent studies involving the use of CT scans to measure hardening of the arteries (in women aged 50 to 59) as well as coronary artery calcium have confirmed very low or nil risk.
Scientists followed about 750 women over seven years. Half the women took 1,000 milligrams of calcium and 400 units of vitamin D every day, while the other half took no supplements. Scientists found no difference in the arteries of the two groups.
The study was published in the journal Menopause.

* There is some evidence that adequate vitamin K2, magnesium and several B vitamins, also affect how efficiently calcium can be used. Vitamin K2 may help direct calcium to the bones, away from the arteries. Vitamin K2 is found in leafy green vegetables and foods such as natto or curd cheeses.
While natto is the most potent natural source of vitamin K2, the nutrient is also readily available in fermented dairy products, especially cheeses.
Most cheeses are rich in vitamin K2… particularly, curd cheese. And even though it’s not as high in vitamin K2 as natto, curd cheese may be more palatable on a day-to-day basis for many people.
Raw curd cheese made from grass fed cows would be best.

* Physical activity has been proven to improve bone strength, so exercise should always be recommended even if calcium intake is sufficient.

* There is universal agreement that everyone needs calcium in their diet.
Current recommendations are 1,000 milligrams daily for adults under 50.
Older adults are advised to get more (around 1,200 milligrams daily).
People who eat less salt, protein and caffeine may not need as high a calcium intake as those who do.

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