Most health agencies recommend that older adults take 1,000-1,200 milligrams of calcium per day to stave off bone loss, or “osteoporosis.” About 43 percent of U.S. adults follow that advice by taking supplements, but in some countries, including New Zealand, calcium-supplement use is falling. “The change wasn’t driven by guidelines; it was actually driven by the media coverage of our paper,” says physician Mark Bolland.

Bolland and his colleagues at The University of Auckland went over evidence from dozens of studies that test calcium supplements’ effects on bone and concluded that the supplements have little to no effect on older adults’ chances of breaking a hip. However, calcium supplements do appear to slightly increase the risk of heart attack.

Case closed? Not quite.

Dr. Richard Prince from the University of Western Australia also studies calcium supplements’ effects on bone and says that the Auckland group’s analyses rely on patient self-reports to count their heart attack numbers. The problem is that patients often misdiagnose themselves by mistaking various chest pains for heart attacks.

The downsides of taking calcium may be smaller than their study suggests, says Prince. Furthermore, even though the benefits of calcium supplements are small, they may make a difference for those most at risk of hip fracture. Most people who stopped taking calcium supplements did so, not based on doctor’s orders, but because of what they heard on the news.

Bolland and his colleagues have suggested that nutrition guidelines recommending calcium supplements have been influenced by connections to the vitamin industry. But given that one of Bolland’s co-authors has received grants and honorariums from pharmaceutical companies that make drugs for osteoporosis (the authors say those funds were NOT used for the calcium supplement study), it’s hard to say whether conflicts of interest are skewing either party’s analysis.

Bottom line: calcium supplements are unlikely to hurt you, unless you’re at high risk for a heart attack. They’re also unlikely to help you, unless you’re at higher-than-average risk of breaking a bone. Experts are still debating whether the benefits outweigh the risks.