Millions of people depend on calcium supplements to keep osteoporosis at bay – especially people with rheumatoid arthritis and other inflammatory forms of the disease. For a variety of reasons, including corticosteroid use and limited activity, they are at increased risk of developing osteoporosis.

Reena L. Pande, MD, a cardiovascular specialist at Brigham and Women’s Hospital in Boston, says this is one of those situations in which it is important for patients to talk with their doctors. 

“Everyone is different,” Dr. Pande says. “For example, for a patient with osteoporosis, or with a specific condition that might be strongly linked with the development of osteoporosis, the benefit of calcium supplementation might outweigh the potential heart risk.”

But Ian Reid, MD, lead author of the New Zealand meta-analysis – which was published in the journal BMJ in April 2011 and looked at more than 29,000 women across 14 trials –  says many physicians may be unaware the evidence is “flimsy” when it comes to the benefits of calcium supplements on bones.

“In our last two meta-analyses, we carefully looked at the risk-benefit in women in their 60s and women in their mid-70s, and in both situations there are more cardiovascular events caused by calcium than there are fractures prevented by it,” says Dr. Reid, professor of medicine and endocrinology at the University of Auckland, New Zealand.

Dr. Reid, who wrote an editorial to accompany the new study, says evidence is growing that when it comes to getting enough calcium, food is the way to go. “I attended an international meeting on nutrition in osteoporosis in Switzerland two weeks ago, and I think it’s true to say that there was a consensus toward advocating dietary calcium in preference to supplements.”

Rohrmann says food seems not only to be a safer way to get calcium – but at a certain level it could actually be beneficial for cardiovascular disease. Her research in Heart found that getting moderately high amounts of calcium from food – 820 milligrams a day, about the amount in two eight-ounce containers of plain yogurt – had a 30 percent reduced risk of heart attack. Consuming much more – or less – than that did not appear to show a protective effect.

Dr. Pande says this latest study only reinforces her view that calcium is best obtained from food.

“Eating a well-rounded and balanced diet is always the most important way to get needed nutrients and vitamins,” she says. “The study was reassuring in that it did not indicate any increased risk for heart problems with dietary calcium intake.”

Dr. Pande says that while the study raises important issues and should be taken seriously, it isn’t perfect.

“It’s an observational study, not a randomized controlled trial, and you always have to take results from these kind of studies with a grain of salt. Furthermore, the numbers of events are small,” she says. Of the 23,980 people studied, only 354 had heart attacks during 11 years (average) of follow-up. “Nonetheless, the study raises the possibility that calcium supplements might increase risk of heart attacks. Further studies would be needed to know if this is indeed real or just an association.”