It has long been thought that vitamin D supplements can help protect patients from bone fractures. But a recent study published in the New England Journal of Medicine found that those supplements had no effect on bone fracture rates, leading some experts to suggest providers reconsider recommending the supplements.
Cheat sheets: Evidence-based medicine 101
For the study, researchers looked at 25,871 adults who were enrolled in the VITAL study—a broader study on the effects of vitamin D—funded by NIH.
Study participants were men ages 50 and older and women ages 55 and older. Participants in the study were given either a dose of 2,000 international units of vitamin D or a placebo pill, and then reported any incidents of bone fracture for a median of 5.3 years.
The researchers found that the vitamin D pills had no effect on bone fracture rates, including among those who have osteoporosis and those whose blood tests determined they were vitamin D deficient. Rates of nonvertebral fractures and hip fractures held roughly the same between those taking the placebo and those taking the supplement.
In an editorial accompanying the study, Steven Cummings, a research scientist at the California Pacific Medical Center Research Institute, and Clifford Rosen, a senior scientist at the Maine Medical Research Institute and an editor at NEJM, wrote that providers "should stop screening for 25-hydroxyvitamin D levels or recommending vitamin D supplements and people should stop taking vitamin D supplements in order to prevent major diseases or extend life."
However, Cummings and Rosen added that there are some patients who may still benefit from the supplements, including those with celiac or Crohn's disease, as well as "persons living in residential settings with little or no sunlight exposure or malabsorption or those receiving treatments for osteoporosis that might cause hypocalcemia."
But aside from those specific scenarios, "the use of the terms vitamin D 'insufficiency' and 'deficiency' should now be reconsidered," they wrote.
JoAnn Manson, chief of preventive medicine at Brigham and Women's Hospital and leader of the VITAL trial, said the study was large enough that thousands of people with osteoporosis and insufficient vitamin D levels were included. This allowed the researchers to determine that they specifically did not see a benefit in fracture reduction from vitamin D supplements.
"That will surprise many," she said. "But we seem to need only small-to-moderate amounts of the vitamin for bone health. Larger amounts do not confer greater benefits."
Peggy Cawthon, scientific director of the California Pacific Medical Center Research Institute and a coauthor on the study, said the results "questio[n] whether or not there's too much screening for vitamin D deficiency and whether people without specific risk factors should be taking vitamin D supplements to improve their health." Instead of using supplements, providers and patients should look to other interventions like osteoporosis medication to increase bone density.
Despite the study results, Sundeep Khosla, a professor of medicine and physiology at the Mayo Clinic, said he still intends to advise his osteoporosis patients to take vitamin D supplements since they "will do little or no harm and may have benefits."
"I will still tell my family and friends who don't have osteoporosis to take a multivitamin a day to make sure they don't get vitamin D deficient," he added. (Kolata, New York Times, 7/27; Welle, STAT News, 7/27; Monaco, MedPage Today, 7/27)