BOSTON (AP) — The latest news about calcium and vitamin D may not look so encouraging, but most experts say the take-home message is the same: Keep taking your pills.

The biggest study ever to examine the value of the supplements suggests they convey only limited protection against broken bones. They failed to protect against most fractures in low-risk women, but seemed to offer some benefit against hip breaks among women over 60 and those who took the pills most faithfully.

The outcome could affect an enormous number of people, since an estimated 10 million Americans have break-prone bones thanks to osteoporosis. One of two women will suffer such a fracture in her lifetime.
Doctors, who have long taken the value of these supplements almost as an article of faith, tried to put the findings as positively as possible.

“We still do believe ... that maintaining an adequate calcium intake will lay the foundation for bone health,” said lead author Dr. Rebecca Jackson at Ohio State University.

But some disappointment seeped out at the margins. The study is “not as ringing an endorsement of calcium as one might like,” said one of the researchers, Dr. Norman Lasser at New Jersey Medical School.

The study’s findings were published Thursday in The New England Journal of Medicine. They were a long-awaited offshoot of the big national study of diet and hormone therapy known as the Women’s Health Initiative.

The seven-year study of 36,282 women ages 50 to 79 gave half the participants 1,000 milligrams of calcium and 400 units of vitamin D, while the other half took dummy pills.

However, many were also taking their own supplements before the research began, and they were allowed to keep doing so, whether they were assigned to the test group or the comparison group. These extra supplements may have helped the women stay healthy but ironically diluted the findings, since any benefit is harder to show against a backdrop of fewer fractures.

“There’s probably a small benefit,” said Dr. Joel Finkelstein, of Massachusetts General Hospital, who wrote an editorial to accompany the study. “It’s a good start, but women at higher risk need to know it’s not enough.”

Many experts down played the meaning of the negative finding. Dr. Bess Dawson-Hughes, a Tufts University vitamin expert who helped shape the dietary guidelines, said they should remain unchanged for now.