Taking vitamin D and calcium supplements may not help prevent bone fractures in postmenopausal women, according to a new report from a government-appointed panel of experts.
The report found no evidence that taking up to 400 international units (IUs) of vitamin D and 1,000 milligrams of calcium supplements a day reduced the risk of fracture in healthy postmenopausal women. In fact, the report found that these doses of vitamin D and calcium slightly increased the risk of kidney stones. Because of this lack of benefit, the panel, known as the U.S. Preventive Services Task Force, said healthy postmenopausal women should not take vitamin D and calcium supplements at or below these dosage levels (400 IUs for vitamin D and 1,000 mg for calcium) for the purpose of preventing fractures.
However, more research is needed to determine whether or not higher supplement doses can prevent fractures, the task force said.
There was also insufficient evidence to recommend for or against use of vitamin D and calcium supplements at any dose level to prevent fractures in men, or in women before they enter menopause, the task force said.
The recommendations are only intended for healthy people, and not for individuals living in nursing homes or other institutionalized settings, the task force said.
Ultimately, the decision about whether or not take vitamin D or calcium supplements should be made between a patient and his or her doctor, said Dr. Linda Baumann, a professor emerita at the University of Wisconsin-Madison School of Nursing, and a member of the task force panel.
The Institute of Medicine said people need between 600 and 800 IUs of vitamin D a day, and between 700 and 1,300 mg of calcium a day, depending on their age. While most people in the United States get enough vitamin D and calcium, older adults sometimes fall short of the recommendations and need to increase their intake through food or with a supplement. [See New Rules on Vitamin D and Calcium: Most People Get Enough.]
The task force recommends taking a vitamin D supplement containing about 800 IUs for the prevention of falls in older adults ages 65 and over who are at risk for falls because they are vitamin D deficient or because they have a history of a recent fall.
The task force also recommends screening women ages 65 and older for osteoporosis as well as younger women who are at an increased risk for fractures.
About 50 percent of postmenopausal women will suffer a fracture related to osteoporosis during their lifetime, and fractures in older adults increase the risk of death, the task force said.
Because calcium helps build bone, and vitamin D helps bones absorb calcium, doctors frequently recommend taking vitamin D and calcium supplements to prevent fractures. Surveys estimate that close to 60 percent of women ages 60 and over take vitamin D supplements or calcium supplements. However, whether these supplements actually prevent fractures was not clear.
The new report reviews the results of six trials in which adults were randomly assigned to take daily vitamin D and calcium supplements or a placebo.
The largest study involved 36,282 postmenopausal women ages 50 to 79 who took either 400 IUs of vitamin D and 1,000 mg of calcium daily or a placebo. After seven years, women who took vitamin D and calcium supplements were just as likely to sustain a fracture as women who took the placebo. Individuals in the supplement group were slightly more likely to develop a kidney stone compared with those in the placebo group (2.5 percent versus 2.1 percent). For every 273 women who took the supplements, one developed a kidney stone, the researchers said.
After the development of the new task force recommendations, a new review study was published that suggested that vitamin D doses of 800 IUs or more reduced the risk of fractures in people ages 65 and older. But this finding did not always hold when the researchers took into account other factors that may have influenced the risk of fractures, such as whether or not participants were taking calcium supplements as well. More studies need to be conducted with higher vitamin D doses to confirm the results, Baumann said.
An across-the-board recommendation for vitamin D and calcium supplementation in adults is hard to make because people differ in their risk for fractures and kidney stones, said Dr. Neil Roth, an orthopedic surgeon at Lenox Hill Hospital in New York who was not involved in the new report. Among doctors, recommending these supplements seemed logical because they are low-cost, relatively low-risk, and provide a potential benefit, Roth said. But before recommending supplements, doctors should take into consideration how much vitamin D patients get from their diet, from multivitamins and from time spent in the sun, as well as their risk of future fractures and kidney stones, Roth said.
The best way to get vitamin D is through foods such as milk, yogurt, cheese and foods fortified with calcium, according to the American Society for Bone and Mineral Research. Healthy adults who get enough vitamin D through their diet and sunlight exposure don't need to take supplements for bone health, said Dr. Cliff Rosen, past president of the ASBMR. But those at high risk of facture, such as elderly adults living in nursing homes who get little sunlight exposure, should be taking supplements, Rosen said.
The new task force recommendations is published Feb. 26 in the journal Annals of Internal Medicine.
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