Bad bones.

Calcium and vitamin D supplements failed to prevent broken bones in two studies of older women at high risk for fractures.

One study tested calcium (1,000 mg a day) and/or vitamin D (800 IU a day) or a placebo on more than 5,000 people (mostly women) aged 70 or older who had already suffered one bone fracture because of osteoporosis. The second study tested the same two supplements (but no placebo) on more than 3,300 women with at Feast one risk factor for hip fracture (a previous fracture, low body weight, smoker, family history of hip fracture, or "fair" or "poor" self-reported health).

After two years, both studies found no lower fracture rates among those who were given supplements than among those who were not. But by the end of the first year, only 50 to 60 percent of the participants were still taking their pills, which could help explain why the fracture rates were no different*

What to do: If your bones are over 70 and already weak enough to have broken once, taking extra calcium and vitamin D may not help prevent another fracture. Talk to your doctor about whether to take bone-strengthening drugs.

Until more studies are done, stick to the recommended levels of calcium (1,000 mg if you're under 50 and 1,200 mg if you're over 50) and vitamin D (400 IU if you're under 70 and 600 IU if you're over 70).

Lancet 365: 1599, 1621, 2005 BMJ 330: 1003 2005.