By Barbara Bronson Gray
MONDAY, Feb. 25 (HealthDay News) -- Healthy older women should not take calcium and vitamin D supplements to prevent fractures, according to a final recommendation issued Monday by the U.S. Preventive Services Task Force.
In healthy adults, lower doses of calcium and vitamin D seem to be ineffective. As for higher doses, it's still up in the air, the government group said.
The new recommendations do not apply to people who are known to be vitamin D-deficient or who already have osteoporosis, the U.S. Preventive Services Task Force (USPSTF) noted.
Every year about 1.5 million fractures in the United States are attributed to osteoporosis, which is caused by a decrease in bone mass and density that makes bones fragile and more susceptible to a break. Almost half of all women older than 50 will have an osteoporosis-related fracture in their lifetime, according to the USPSTF.
Calcium is one of the main building blocks of bone growth, and vitamin D (sourced via sunlight's action on the skin, or through diet) helps bones absorb calcium. But at issue is whether people receive enough of these nutrients in their daily diet, or if supplements would help protect them.
Dr. Virginia Moyer, chair of the USPSTF, and a professor of pediatrics at Baylor College of Medicine, said experts know that a "medium dose" of supplements -- less than 400 international units (IU) of vitamin D and less than 1,000 milligrams (mg) of calcium -- does not work.
As for higher doses? "We simply don't know. There are reasons to think they could work, but unfortunately, even though there are a bunch of studies, there are problems with them," Moyer said.
"We know these recommendations will be very frustrating to both physicians and patients, but it's a call to action to the research community," she added.
The USPSTF analyzed a wide range of studies on the effects of supplementation of vitamin D and calcium levels for bone health and the adverse effects of supplementation. The report, published online Feb. 26 in the Annals of Internal Medicine, makes these points about preventing fractures:
- Don't take low doses of daily supplements: Less than 400 IU of vitamin D and less than 1,000 mg of calcium after menopause have no benefit.
- For higher doses: The task force doesn't have sufficient evidence to make a recommendation on daily supplements.
- For men and women younger than 50: The task force also doesn't have enough evidence to make a recommendation on vitamin D and calcium supplements.
The report notes a downside to low-dose supplementation: Taking 400 IU or less of vitamin D and 1,000 mg or less of calcium increases the risk of kidney stones, which can be painful and may require hospitalization.
Criticism about the USPSTF guidelines comes from a range of perspectives.
The Council for Responsible Nutrition, a trade association representing the dietary supplement industry, criticized the USPSTF for relying too heavily on data from the Women's Health Initiative (WHI), a study that showed little to no effect on fracture rates in the more than 35,000 postmenopausal women in the trial. They also said that the task force ignored a WHI study out this year that showed a notable reduction in fracture among women who adhered to prescribed doses of calcium and vitamin D.
Some experts prefer a report released by the Institute of Medicine (IOM), a nonprofit organization that gives expert, evidence-based advice on public health issues to policy makers and health professionals.
"That took a very in-depth and I would say a very broad look at the vitamin D and calcium question," said Dr. Sundeep Khosla, a past president of the American Society for Bone and Mineral Research and an endocrinologist and research scientist at the Mayo Clinic. The IOM recommended that most adults get 1,000 mg of calcium, and that women older than 50 and men older than 70 get 1,200 mg of calcium, according to Khosla.
Khosla said the IOM and the USPSTF were each "looking at different parts of the elephant." He said that the USPSTF was focused just on what it took to prevent fracture, ignoring the fact that among healthy people who haven't yet had a break, it would be difficult to detect whether supplements are effective.