A federal panel has confirmed its initial recommendation against taking vitamin D and calcium supplements to prevent fractures after a review of scientific evidence found there is not enough evidence to suggest it will prevent broken bones in most postmenopausal women or in men.
The US Preventive Services Task Force, which released its final report Monday, reached the decision despite resistance from some physicians and supplement industry groups, which argued that taking such supplements is effective in preventing bone fractures as well as some types of cancers.
After reviewing scientific research on vitamin D and calcium, the panel recommended against daily vitamin D doses of 400 international units (IU) or lower and calcium doses of 1,000 milligrams or lower for postmenopausal women who are not vitamin D deficient or do not have osteoporosis. There is not enough evidence to suggest that the same doses would help men or that higher doses would benefit both men and women, the panel concluded.
The final draft, which was published Monday in the Annals of Internal Medicine, warns consumers that risks such as kidney stones from taking the supplements could outweigh any potential benefits.
“Vitamin D and calcium are critical to bone health,” said Linda Baumann, professor of nursing at the University of Wisconsin Madison and a member of the Task Force. “But the evidence doesn’t show that supplementation leads to less fracture.”
Twenty percent of American adults take vitamin D supplements and 17 percent take calcium supplements, according to the 2012 Consumer Survey on Dietary Supplements by the Council on Responsible Nutrition, a supplement industry trade group.
But some nutritionists say not all adults who take supplements need them.
“What is invariably found in these studies is if people have a good diet and are physically active and go outside that they don’t need these additional supplements,” said Marion Nestle, professor of nutrition, food studies, and public health at New York University.
The panel’s draft recommendations, issued in June 2012, drew criticism from some experts.
According to Baumann, much of the evidence was based on the Women’s Health Initiative, the largest randomized trial on the supplement combination, which found no benefit in preventing fractures among women who took 400 IU of vitamin D and 1,000 mg of calcium daily.
However, the study contained major flaws. Significant numbers of women in the treatment group did not take the daily dosage of calcium, and many women in the control group took supplements on their own.
“Some also question whether the dosage was high enough to give an effect,” said Baumann. “Maybe not, but there should be other studies to show otherwise.”
Marion, who co-authored an editorial accompanying the recommendation, said she would “prefer to err on the side of caution,” and discontinue taking the pills.
“But for a lot of people who take them, it’ll be easier to just continue to take a supplement,” she said.
For some, insufficient evidence of benefits or risks from taking the supplements may raise more questions than provide answers.
“The USPSTF recommendations should be further reviewed and discussed within the scientific and medical communities before consumers jump to change their supplementation habits,” the Council for Responsible Nutrition said in a public statement.
Baumann said that women who take vitamin D and calcium should talk to their doctor before stopping.
“We would recommend that anyone talk to their health care provider about their individual risk,” she said. “And then just weigh the harms and benefits, but don’t approach this as a blanket recommendation for all adults.”
In May 2012, the same panel recommended vitamin D and calcium supplements to prevent falls in seniors who were at an increased risk of falling. Later this year, the task force plans to publish final recommendations on the combination supplements and its potential to prevent some forms of cancer.
“When it does, we hope it will keep in mind the value of making a single recommendation about vitamin D and calcium supplementation that will encompass all potential benefits and risks,” Nestle wrote in the editorial. “Multiple recommendations by condition confuse practitioners and the public.”