The authors say older people who eat less have fewer opportunities to pack away sufficient quantities of calcium-dense foods such as milk, cheese, yogurt and leafy green vegetables.
Stephen Walsh, the lead author, says appetites tend to diminish as people age, so people 50 and older need to make a conscious effort to eat more foods with calcium — and make up the shortfall with supplements. A typical older adult, for example, may get 300 mg of calcium a day from non-dairy sources (such as salad greens or salmon) and then have a glass of milk or a yogurt for a total of 600 mg. But that isn't enough calcium, he warns.
"You need about twice as much as that to keep your bones strong, especially if you're a woman whose need for this nutrient increases after menopause," says Walsh, a biostatistician and an associate professor at the University of Connecticut School of Nursing.
Ideally, people should get their calcium through food. Last year a large study found that calcium supplements may raise the risk of heart attack, and research in 2007 found postmenopausal women who got most of their daily calcium from food had healthier bones than those who took supplements.
Kimberly O'Brien, professor of human nutrition at Cornell University, who was not involved in this latest study, says the research shows that women are more likely than men to take calcium supplements.
"These findings demonstrate the need for increased awareness among older Americans about calcium and other nutrients that are required for bone health," she says.
The research was published in the Journal of the American Dietetic Association.
Also of interest: Your essential guide to vitamins. >>
Joan Rattner Heilman frequently writes for the AARP Bulletin.