The idea made so much sense that it was accepted almost without question: Vitamin D pills can protect bones from fractures. After all, the body needs the vitamin for the gut to absorb calcium, which bones need to grow and stay healthy.
But now, in the first large randomized controlled trial in the United States, funded by the federal government, researchers report that vitamin D pills taken with or without calcium have no effect on fracture rates. The results, published Thursday in The New England Journal of Medicine, apply to people with osteoporosis and even people whose blood test found them to be vitamin D deficient.
These results followed other conclusions from the same study that did not support a long list of purported benefits of vitamin D supplements.
So for the millions of Americans who take vitamin D supplements and the labs that do more than 10 million vitamin D tests each year, an editorial published in conjunction with the paper has one piece of advice: Stop.
“Providers should stop screening for 25-hydroxyvitamin D levels or recommending vitamin D supplements and people should stop taking vitamin D supplements to prevent serious illness or prolong life,” wrote Dr. Steven R. Cummings, a researcher at the California Pacific Medical Center Research Institute, and Dr. Clifford Rosen, a senior scientist at the Maine Medical Research Institute. dr. Rosen is an editor at The New England Journal of Medicine.
There are exceptions, they say: People with conditions such as celiac disease or Crohn’s disease need vitamin D supplements, as do those who live in conditions where they don’t have sunshine and may not get any of the minerals from foods that are routinely supplemented with vitamin D, such as grains and dairy products.
Getting into such a severe vitamin D-deficient condition is “very difficult for the general population,” said Dr. Cummings.
The two scientists know that by making such strong statements, they are hiring vitamin vendors, testing labs and advocates who claim that taking vitamin D, often in huge amounts, can cure or prevent a wide variety of ailments and even help people live longer.
Doctors often check for vitamin D levels as part of routine blood tests.
The study included 25,871 participants — men age 50 and older and women age 55 and older — who were assigned to take 2,000 international units of vitamin D or a placebo each day.
The study was part of a comprehensive vitamin D study called VITAL. It was funded by the National Institutes of Health and started after an expert group convened by what is now the National Academy of Medicine, a nonprofit organization, examined the health effects of vitamin D supplements and found little evidence. The members of the expert group were required to come up with a minimum daily requirement for the vitamin, but found that most of the clinical studies that had studied the subject were inadequate, leaving them questioning whether there was any truth to the claims that vitamin D improved health.
The prevailing view at the time was that vitamin D would prevent bone fractures. Researchers thought that if vitamin D levels fell, parathyroid hormone levels would rise at the expense of the bones.
dr. Rosen said these concerns led him and the other members of the National Academy of Medicine’s expert group to set an “arbitrary value” of 20 nanograms per milliliter of blood as the target for vitamin D levels and recommend taking 600 to 800 international units of vitamin D supplements to achieve that goal.
Laboratories in the United States then arbitrarily set 30 nanograms per milliliter as the cutoff for normal vitamin D levels, a value so high that almost everyone in the population would be considered vitamin D deficient.
The supposed relationship between vitamin D and parathyroid levels has not held up in follow-up research, said Dr. rosen. But the uncertainty persisted, so the National Institutes of Health funded the VITAL study to get solid answers about the relationship between vitamin D and health.
The first part of VITAL, published earlier, found that vitamin D did not prevent cancer or cardiovascular disease in trial participants. Nor did it prevent falls, improve cognitive function, reduce atrial fibrillation, alter body composition, reduce migraine frequency, improve stroke outcomes, protect against macular degeneration, or reduce knee pain.
Another large study, in Australia, found that people who took the vitamin no longer lived.
dr. JoAnn Manson, chief of preventive medicine at Brigham and Women’s Hospital at Harvard Medical School and the leader of the main VITAL study, said the study was so large that thousands of people with osteoporosis or who had vitamin D levels in a range were considered low or “inadequate”. That enabled the researchers to determine that they also received no fracture reduction benefit from the supplement.
“That will surprise many,” said Dr. manson. “But we seem to need only small to moderate amounts of the vitamin for bone health. Larger amounts do not provide greater benefits.”
The lead author and principal investigator of the bone study, Dr. Meryl S. LeBoff, an osteoporosis expert at Brigham and Women’s Hospital, said she was surprised. She had expected benefits.
But she cautioned that the study didn’t address the question of whether people with osteoporosis or low bone mass just below the condition should take vitamin D and calcium along with osteoporosis medications. Professional guidelines say they should take vitamin D and calcium, and she will continue to adhere to them in her own practice.
dr. Dolores Shoback, an osteoporosis expert at the University of California, San Francisco, will also continue to advise patients with osteoporosis and low bone mass to take vitamin D and calcium.
It’s “a simple procedure and I will continue to prescribe it,” she said.
Others go a little further.
dr. Sundeep Khosla, a professor of medicine and physiology at the Mayo Clinic, said that since vitamin D “will do little or no harm and may have benefits,” he would continue to advise his patients with osteoporosis to take it, recommending the 600 . up to 800 units per day in the National Academy of Medicine report.
“I will still tell my family and friends who do not have osteoporosis to take a multivitamin a day to make sure they are not deficient in vitamin D,” he said.
dr. Khosla follows that advice herself. Many multivitamin tablets now contain 1,000 units of vitamin D, he added.
But dr. Cummings and Dr. Rosen remain steadfast, even questioning the idea of a vitamin D deficiency for healthy people.
“If Vitamin D Doesn’t Help, What Is a Vitamin D Deficiency?” asked Dr. Cummings. “That means you need to take vitamin D.”
and dr. Rosen, who signed the report from the National Academy of Medicine, has become a vitamin D therapeutic nihilist.
“I don’t believe in 600 units anymore,” he said. “I don’t believe you should do anything.”