A government advisory panel's recommendation Tuesday that healthy postmenopausal women should not take daily low doses of vitamin D and calcium to prevent bone fractures is a wakeup call to millions of Baby Boomer women that more is not always better.
The panel said there is insufficient evidence to evaluate larger doses, easy to overdo with chewy chocolate supplements that can seem like candy.
In its draft recommendations, the U.S. Preventive Services Task Force also said existing research is insufficient to assess the risks or benefits of taking vitamin D -- with or without calcium -- to prevent cancer in adults.
Some studies link higher levels of vitamin D with lower rates of colorectal cancer and reduced risks for other cancers, including breast, prostate and pancreatic. These reports are mixed and therefore inconclusive, said the advisory panel.
This is the same panel that grabbed headlines recently by advising against PSA (prostate-specific antigen) tests to screen for prostate cancer in healthy men and told women 50-74 to have a mammogram every other year, not annually.
This latest report adds to many conflicting messages about the benefits and risks of vitamin D and calcium supplements.
For years, experts have touted benefits of these nutrients, key for bone health. The Institute of Medicine recommends 600 to 800 units of vitamin D and 700-1,300 milligrams of calcium daily.
The task force looked at doses up to 400 IU (international units) of vitamin D and 1,000 mg. of calcium for fracture prevention. Nearly half of all women older than 50 will have an osteoporosis-related fracture during their lifetime, it says.
"The science is still out" on whether pre-menopausal women and men should take low-dose supplements to prevent fractures, says Timothy Wilt, lead author of the panel report.
The studies that the panel analyzed have important limitations, says Jen Sacheck, assistant professor at Tufts University in Boston.
"It's a more complex picture than they're painting," she says. "If you live in New England, there are many months of the year when you're not getting adequate amounts of vitamin D from the sun. "
Taylor Wallace of the Council for Responsible Nutrition, a supplement industry group, says about 22% of U.S. adults report taking calcium supplements, 22% vitamin D.
"We recommend consumers read the labels," he says. With some supplements, "more is not always better, including for the tasty stuff like the soft chews, where people might be tempted to eat a bit more."
Suzanne Steinbaum, director of women and heart disease at Lenox Hill Hospital in New York and an American Heart Association spokeswoman, says the recommendation "changes everything. Even if you are at risk for a fracture, maybe you have to try other lifestyle changes, like diet and weight-bearing exercise."
"The key point about calcium is that more is not better," says JoAnn Manson, chief of preventive medicine at Brigham and Women's Hospital in Boston and an investigator with the Women's Health Initiative.
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