Delicious Living Blog

Why you should take the calcium/heart attack study with a grain of salt

Wondering about the relevance of the recent study linking calcium supplements to heart attack risk? So is Robert Rountree, MD, Boulder, Colo.-based integrative physician and Delicious Living's medical editor.

In the editorial offices at New Hope Natural Media, we've all been buzzing about the recent Zurich University study by Sabine Rohrmann, et al., which claimed to find a significantly increased risk of myocardial infarction (MI)—but not stroke—in people who take calcium supplements.

What gives? And what will be the shakeout for one of the most widely taken dietary supplements ever? (My colleague Todd Runestad wrote the first sally on this issue in a recent blog.)

In such matters, I am always grateful for the seasoned perspective of Robert Rountree, MD, a renowned, longtime integrative physician, and the medical editor who scrutinizes all of Delicious Living's articles.

His objections to the EPIC-Heidelberg study methodology follow, along with citations of well-designed studies that came to quite different conclusions about calcium and heart-attack risk.

"The way that the [EPIC-Heidelberg] assessment was performed was by giving people a questionnaire that asked whether they took a multivitamin and or calcium supplement. In other words, use of calcium supplements were entirely self-reported—a serious flaw. Furthermore, they did not ask the participants how much calcium they were taking, an omission that indicates a serious lack of understanding of nutritional principles. In other words, participants could have been taking as little as 100 mg or as much as 2000 mg of calcium. It doesn't make any sense to me to conclude that the effect would be the same regardless of the dose.

In contrast, consider this 2012 review of calcium intake and risk of CV disease by Sesso et al. at Brigham and Women's Hospital and Boston. They point out the major flaws in previous meta-analyses and conclude that the effect of calcium on CV disease is negligible.

If calcium supplements increase the risk of heart attacks, the assumption is that they would do so by increasing calcification of the arteries. Unlike the Swiss study, which simply looked at the incidence of heart attacks, this 2009 study from the Mayo Clinic actually measured aortic valve and coronary calcification for up to three years after the patient started taking calcium supplements. They did not find any significant progression of calcification.

One other thing to note: The Swiss researchers only found 354 heart attacks in the 11 years that the 24,000 men and women were followed. That is a very small number. When you are dealing with numbers that small, it doesn't take a big increase in the actual numbers to have a huge increase in the percent change."

How negatively do you think this research news will affect sales (and formulations) of calcium supplements? How can the industry best respond? Leave a comment.

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