While too little calcium and vitamin D can increase a risk of broken bones, too much may increase the risk of heart attack and stroke, Norwegian researchers have found.

“We conclude that the moderate effect of supplemental calcium and vitamin D on the risk of fractures is not large enough to outweigh the potential increased risk of cardiovascular disease, specifically in women who are at a low risk of bone fracture,” said Gunhild Hagen, a Ph.D. candidate at the Norwegian University of Science and Technology’s (NTNU) Department of Public Health and General Practice who was first author of an article recently published in Osteoporosis International.

Using an advanced analytical model, the researchers said healthy women aged 65 would be less likely to have a hip fracture, but more likely to have a heart attack or a stroke.

It is not clear that calcium increases the risk of heart disease, but Hagen said caution indicates choosing another treatment to prevent broken bones in older women.