Vitamin D pills don't prevent fractures, research suggests

Almost half of people 50 and older use vitamin D supplements. But there's little evidence that taking them improves bone health in people who aren't deficient in the vitamin, according to an article published this week in The Lancet.

"Most healthy adults do not need vitamin D supplements," said the lead researcher Ian Reid, M.D., from the University of Auckland in New Zealand in a statement that accompanied the article. "Our data suggest that the targeting of low-dose vitamin D supplements only to individuals who are likely to be deficient could free up substantial resources that could be better used elsewhere in health care."

The team of New Zealand researchers analyzed data on 4,082 healthy adults age 59, on average, in 23 randomized controlled trials. All involved vitamin D pills; half were D and calcium supplements. The researchers studied vitamin D alone because of recent concerns about the cardiovascular safety of calcium supplements. Vitamin D supplementation for 2 years did not build bone mineral density in the the spine, hip, or foream.  

Read our earlier reports "Most vitamin D pills measure up, our tests find" and "Do you really need more vitamin D?"

Peole who took calcium and vitamin D were slightly less likely to suffer fractures, the studies found, and to have a modest increast in hip bone mineral density. But they fared no better than people who too just calcium.  

Bottom line: Taking vitamin D pills to prevent osteoporosis in healthy adults is not warranted, wrote Clifford J. Rosen of the Maine Medical Research Institute in Scarborough, Maine, in an accompanying commentary. But maintaining vitamin D levels combined with sufficient dietary calcium intake of 800 to 1,200 mg per day remains an effective approach for preventing hip fractures in seniors.

If you are taking vitamin D supplements for your bone health, ask your doctor whether you should. And you should be cautions about supplemental calcium, too, since some research has linked calcium supplements to heart attacks. That concern is a reminder that it's better and safer to get your nutrients from food, such as dairy products and green leafy vegetables, rather than pills. And since the body makes vitamin D from exposure to sunlight, you can help maintain your stores by getting some midday sun exposure during the warmer months or regularly consume vitamin D-rich foods such as fatty fish, eggs, and fortified milk or soy products.

—Doug Podolsky