Theyre supposed to protect your bones from the brittle risks of osteoporosis. But calcium supplements may be breaking your heart instead. A new study published online April 19 in BMJ finds that calcium supplements may increase the risk of heart attack and stroke by approximately 20 percent, regardless of whether they include vitamin D. "I think it is an interesting study," says cardiologist Leslie Cho, MD, Director of Preventive Cardiology and Rehabilitation at Cleveland Clinic. "However, it is a meta analysis that has lots of limitation… It is interesting and it requires further studies but it is in no way definitive study. Based on this one study, I am not sure that we should be making broad changes."