But doctors aren't advising that older people stop taking in calcium or give up on exercise. And the study found that even the very elderly can help their bones by doing things like quitting smoking and, if they're women, taking estrogen.
The research, which studied bone density in 800 people ranging from 67 to 90 years old, was published in the Journal of Bone and Mineral Research.
"We looked and were surprised to find bone loss was not refuted by such things as excessive intake of vitamin D and calcium," says Marian T. Hannan, PhD, senior research associate at the Hebrew Rehabilitation Center for the Aged in Boston. "From the data we have here, calcium intake had no relationship to bone loss and neither did vitamin D levels."
Hannan's study also found that exercise did little to preserve bones, and that elderly people who lost weight also lost bone density. Conversely, "women who gained weight also gained bone mineral density," she says. "It may be that for older folks, slight weight gain is beneficial."
Hannan did say "slight." And she didn't say dump calcium entirely. "My personal opinion is that certainly in your adolescent and adult years, calcium is very important. It probably diminishes as we get older and other risk factors increase." Other risk factors identified by the study included smoking and, for women, alcohol consumption and failure to take estrogen.
Hannan drew the study participants from a group of people assembled more than 50 years ago in Framingham, Mass., to study risk factors associated with heart disease over time. Most members of the group have died, but the survivors continue to provide a wealth of information on different aspects of aging.
One near-certainty with advancing age in this group was declining bone density. Almost everyone in the study lost some bone, with women losing it at about twice the rate of men, Hannan says. What she found encouraging in the midst of this depressing news was evidence that even in very old people -- those up to 90 years of age -- there seem to be ways to cut the loss: by stopping smoking, for example, or, for women, starting on estrogen.