Low-dose vitamin D and calcium supplements don't protect bones in healthy post-menopausal women, a task force says. / Sean Dougherty, USA TODAY
Healthy post-menopausal women should not take low-dose vitamin D and calcium supplements in hopes of protecting their bones, a panel of government advisers says in a new recommendation.
The supplements don't work for that purpose, at least when taken at the relatively low daily doses that have been most thoroughly studied, says the U.S. Preventive Services Task Force. The advice, published Monday in the Annals of Internal Medicine, covers daily doses up to 400 international units (IU) of vitamin D and up to 1,000 milligrams of calcium.
The recommendation is an official vote of no confidence in a very popular supplement combination. Though it closely tracks a draft released months ago and is based on widely reported studies, it may come as a shock to many consumers. More than half of U.S. women over age 60 now take the supplements at various doses, according to the task force.
The recommendation also is likely to spawn confusion because it doesn't cover younger women, men or higher doses. The task force says it has inadequate evidence on all those issues. It also continues to study whether vitamin D has any role in preventing cancer. And it is standing by a previous recommendation that people who are over age 65 and at high risk for falls - a big group of people - should take vitamin D supplements.
"We know that vitamin D and calcium are essential to bone health," says task force member Jessica Herzstein, a public-health specialist who is global medical director at Air Products in Allentown, Pa. But studies including the Women's Health Initiative show that low-dose supplements don't prevent fractures in healthy older women, the task force says. Research also suggests that about one in 273 women taking the supplements will develop kidney stones. It's a small risk but worth considering, Herzstein says.
The best advice right now is for women to talk to their doctors about their risks for fragile bones and fractures and all the ways they can prevent them, including diets high in calcium and vitamin D, exercise and prudent sun exposure, which helps the body produce vitamin D, Herzstein says. Some will decide to take supplements anyway, and that's OK, she says. "We're just saying think about it."
But some women who talk with their doctors will find waning enthusiasm for the supplements, says Clifford Rosen, a senior scientist at Maine Medical Center Research Institute and former president of the American Society for Bone and Mineral Research. He says there's a growing consensus that "most people are doing very well in the United States in terms of their vitamin and mineral intake and they don't need supplements." He says there's also growing concern about potential risks.
While daily doses of vitamin D up to 4,000 IU appear safe, he says, recent studies suggesting links between high doses of calcium and heart attack are worrisome. The task force says that link was not found in the studies it reviewed.
Rosen says he still recommends calcium supplements for patients with osteoporosis, whose bones are already fragile, but he tells them that "one pill a day (usually 500 milligrams) is plenty."
Rosen was a member of another advisory panel that developed calcium and vitamin D recommendations for the Institute of Medicine in 2010. That panel concluded that adults need 600-800 IUs of vitamin D and 1,000 to 1,200 milligrams of calcium each day, depending on their age. But it also said most people were getting adequate amounts without resorting to supplements. Some other experts have said the panel relied on blood levels of vitamin D that were too low, and controversy continues about what constitutes vitamin D deficiency and who should be tested and treated for it.
The lack of a single, simple recommendation on vitamin D and calcium is unfortunate for consumers, says Marion Nestle, a professor of nutrition at New York University and co-author of an editorial accompanying the task force report. But, she says, the recommendations are based on what little good science is available.
Nestle says her advice to women is to protect their bones with plenty of exercise and calcium from food, such as dairy products, and vitamin D from "15 minutes a day in the sun." That's something even many dermatologists say is safe, despite the link between sun exposure and skin cancer, she notes.
But many women who rely on the supplements may be scared off by a recommendation based on "a very narrow view of the evidence," says Taylor Wallace, senior director of science and regulatory affairs for the Council for Responsible Nutrition, a trade group representing supplement makers.
"I have a 91-year-old grandmother who takes calcium supplements," he says. "It really scares me that she would see something that says 'stop taking your calcium, stop taking your vitamin D,' when she doesn't go outside and she doesn't eat a lot of dairy."
Any evidence of harm from the supplements "is very weak," he says.
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