“The people in the treatment group were sicker by all the measures we had,” Dr. Center adds. “They had lower bone density, more fractures and weighed less, all of which are associated with an increased mortality.”

Researchers also don’t believe the longer lifespans among those on bisphosphonates can be attributed simply to the fractures prevented, despite the association between fracture and increased risk of death. “There were just not enough of these fractures expected and thus prevented to explain the improvement in survival,” Dr. Eisman explains.

He and his team hypothesize the reduced mortality risk comes from the fact that by preventing bone loss, bisphosphonates are also stopping the release into the blood of heavy metals and potentially other toxic materials stored in the skeleton.

“We know the skeleton is a place where the body stores a lot of things, including heavy metals, we are exposed to throughout our life through gas or eating fish or other things,” Dr. Eisman explains. “With age, as the bone is broken down, these toxic materials are released. If we gave people these bisphosphonates, we have previously shown that it decreased that release.”

Researchers say less than one-third of people with osteoporosis are being effectively treated. If that’s due to concerns that bisphosphonates are connected to unusual fractures of the thighbone or osteonecrosis (bone death) of the jaw, researchers hope this data will lessen those fears by showing a positive side-effect, too.

“We are hoping people may look at this and say, ‘Hang on, these drugs look pretty good and pretty safe.’ This is a good side effect,” Dr. Eisman says.

“It adds to the literature that these medications may have positive effects, and they aren’t all negative effects,” agrees Kathy Weber, MD, a sports medicine physician in the orthopaedics department at Rush University Medical Center in Chicago.

She points out a few study limitations – that there are more females than males, and most are Caucasian. “So you can’t generalize to other ethnic groups and races. It adds to the literature, but the message is, there is still a need for more research and to understand the mechanism that’s adding to the benefit of the mortality reduction.”