Panel questions value of calcium, vitamin D pills

Both nutrients are crucial for healthy bones and specialists advise getting as much as possible from a good diet. The body also makes vitamin D from sunshine. If an older person has a vitamin deficiency or bone-thinning osteoporosis, doctors often prescribe higher-than-normal doses.

But for otherwise healthy postmenopausal women, adding modest supplements to their diet — about 400 international units of D and 1,000 milligrams of calcium — don't prevent broken bones but can increase the risk of kidney stones, the U.S. Preventive Services Task Force said Monday.

It isn't clear if those doses offer bone protection if taken before menopause, or if they help men's bones, the guidelines said.

What about higher-dose supplements that have become more common recently? There's not enough evidence to tell if they would prevent fractures, either, in an otherwise healthy person, the panel concluded. It urged more research to settle the issue.

It's a confusing message considering that for years, calcium and vitamin D supplements have been widely considered an insurance policy against osteoporosis, with little down side to taking them.

"Regrettably, we don't have as much information as we would like to have about a substance that has been around a long time and we used to think we understood," said Dr. Virginia Moyer of the Baylor College of Medicine, who heads the task force. "Turns out, there's a lot more to learn."

The main caution: These recommendations aren't for people at high risk of weak bones, including older adults who have previously broken a bone and are at risk for doing so again, said Dr. Sundeep Khosla of the American Society for Bone and Mineral Research. Those people should consult a doctor, said Khosla, a bone specialist at the Mayo Clinic who wasn't part of the panel's deliberations.