CRN Refutes Meta-Analysis Linking Calcium Supplements to Heart Attack

September 16, 2010

A meta-analysis of 15 studies has concluded that 'calcium supplements are associated with increased risk of myocardial infarction (heart attack),' but the study , published online yesterday at the British Medical Journal, has received swift criticism from industry organizations.

A meta-analysis of 15 studies has concluded that 'calcium supplements are associated with increased risk of myocardial infarction (heart attack),' but the study , published online yesterday at the British Medical Journal, has received swift criticism from industry organizations.

According to the Council for Responsible Nutrition (CRN; Washington, DC), these conclusions are dramatically overstated, considering the limitations of meta-analysis, in general, and this meta-analysis, specifically.

'For example, the analysis could have potentially included over 300 scientific studies on calcium supplementation...s effect on bone, but only 15 randomized clinical trials were deemed '˜eligible for analysis,...' said Andrew Shao, PhD, senior vice president of scientific & regulatory affairs at CRN.
Further, seven of the 15 trials evaluated had no, or incomplete, data on cardiovascular outcomes, and only five of the 15 studies accounted for almost all of the cardiovascular outcomes. Further, because the researchers chose to exclude any trials administering calcium plus vitamin D, many large, important trials'”including the Women...s Health Initiative, which found calcium plus vitamin D had no effect on the risk of coronary heart disease or stroke'”were not included.

'The authors characterize these findings as though all of the selected studies suggest increased risk. In fact, the opposite is true: most of the studies do not suggest increased risk,' said Shao. 'Bone health is one of the most common reasons why health care professionals recommend calcium supplements; there are other health benefits that may be associated with calcium supplementation, such as reduction of colon cancer risk. This is not even considered by the authors. It...s unfortunate that these researchers are making sweeping judgments about the value of calcium supplements by only assessing a handful of handpicked studies.'

Shao also pointed out that none of the original studies included in the meta-analysis were designed to evaluate cardiovascular outcomes. Additionally, the data on cardiovascular events was never previously published, so the meta-analysts had to track the information down separately, in some cases, 10 even 20 years after the original study was published.

'Meta-analysis can be a useful tool for scientific evaluation, but we have to recognize its limitations, and keep in mind that its findings are based on a collection of past studies that may have different designs, doses and study populations,' said Shao. 'This analysis should not dissuade consumers, particularly young women, from taking calcium supplements. They should talk with their doctors about their current and long-term needs and determine how much calcium they are getting from their diets, and supplement accordingly'”likely in combination with vitamin D.'

Original Source: The Council for Responsible Nutrition

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