Taking calcium supplements almost doubles the risk of heart attack, according to new research out of Europe, published in the June 2012 issue of the journal Heart. This finding comes two years after a meta-analysis out of New Zealand linked calcium supplements with an an elevated heart attack risk.

The study in Heart was based on nearly 24,000 residents of Heidelberg, Germany, who are part of a larger study called the European Prospective Investigation into Cancer and Nutrition Study, or EPIC. Researchers were looking at calcium and cardiovascular disease, or CVD, because some previous studies have suggested higher calcium intake may lower the rate of CVD risk factors, such as high blood pressure, type 2 diabetes and obesity. In this study, those who took calcium supplements – especially those who took calcium supplements only, and no other supplements – had an 86 percent higher risk of heart attack compared with people who did not take calcium supplements.

“[Calcium] intake from diet is important, but we should be more cautious about just using a pill instead of thinking about a more healthy, mixed diet,” says study co-author Sabine Rohrmann, PhD, MPH, head of the division of cancer epidemiology and prevention at the University of Zurich in Switzerland.

The researchers suggest calcium from supplements may be problematic for the cardiovascular system because it causes a spike in blood calcium levels, versus the gradual rise that occurs when calcium is obtained from food. And several other studies have linked high blood calcium levels with vascular calcification – basically, a buildup of calcium in blood vessels, which is a precursor to atherosclerosis and other cardiovascular diseases.

“[The] next important steps are to examine which mechanisms do promote the effects of elevated blood calcium levels,” says Rohrmann.

This study did not have information on the amount of calcium participants took. However, the New Zealand meta-analysis that linked calcium with heart attacks cited clinical trials where participants took 1,000 mg daily. Researchers agree more study is needed to determine whether a lower dosage is safer.