More than half of American women older than 60 take vitamin D and calcium supplements, but the U.S. Preventive Services Task Force said recently that they're probably wasting their money.
In a new recommendations from the federal government's expert panel on preventive medicine, the task force says that most postmenopausal women should not take vitamin D and calcium to reduce their risk of bone fractures. The dosages assessed were 400 international units of vitamin D3 and 1,000 milligrams of calcium per day.
The conclusions are based on an analysis of six randomized trials designed to study the health effects of vitamin D and calcium supplements. The largest of these trials was the Women's Health Initiative study, which involved more than 36,000 women between the ages of 50 and 79. That study found no statistically significant difference in the risk of hip or other fractures among women taking the supplements and those who took placebos.
However, the analysis also made clear that this level of vitamin D and calcium supplementation increases the risk of kidney stones. The added risk is small, but considering the lack of demonstrated benefits, even a small risk can't be justified, the panel said.
The task force also considered whether men and younger women should take the supplements to prevent fractures and determined that there wasn't enough clinical evidence to make a call one way or the other.
"The balance of benefits and harms cannot be determined," Dr. Virginia A. Moyer wrote on behalf of the task force in a study published online by Annals of Internal Medicine.
In a previous analysis, the task force found that senior citizens at increased risk for falls should take about 800 IUs of vitamin D a day. That recommendation hasn't changed.
In an editorial in Annals, nutrition experts Marion Nestle of New York University and Malden Nesheim of Cornell University said the new, unambiguous recommendations should prompt doctors to think twice before advising their healthy postmenopausal patients to take calcium and vitamin D.
"In the absence of compelling evidence for benefit, taking supplements is not worth any risk, however small," they wrote.
The panel said it would consider the role of vitamin D and calcium for cancer prevention in a future analysis.