The idea made so much sense that it was accepted almost unconditionally: Vitamin D pills can protect bones from fractures. Finally, the body needs the vitamin for the gut to absorb calcium, which bones need to grow and stay healthy.
But now researchers in the first large randomized controlled trial in the United States, funded by the federal government, report that vitamin D pills taken with or without calcium have no effect on bone fracture rates. The findings, published Thursday in the New England Journal of Medicine, apply to people with osteoporosis and even those whose blood tests showed vitamin D deficiency.
These results followed other conclusions from the same study, which found no support for a long list of purported benefits of vitamin D supplements.
For the millions of Americans who take vitamin D supplements and the labs that perform more than 10 million vitamin D tests each year, an editorial published with the newspaper offers some advice: Stop it.
“Providers should stop looking 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, senior scientist at the Maine Medical Research Institute. dr Rosen is editor of the New England Journal of Medicine.
There are exceptions, they say: People with conditions like celiac disease or Crohn’s disease need vitamin D supplements, as do those who live in conditions where they’re sun-deprived and may not get any of the minerals from foods routinely used Vitamin D supplements can be taken like cereals and dairy products.
Getting into such severe vitamin D deficiency is “very difficult to accomplish in the general population,” said Dr. Cummings.
The two scientists know that with such strong claims they are taking on vitamin vendors, testing labs and advocates who have claimed that taking vitamin D, often in large amounts, can cure or prevent a wide variety of diseases and even help people to live longer.
Vitamin D levels are often checked as part of routine blood tests.
The study involved 25,871 participants – men 50 and older and women 55 and older – who were given 2,000 international units of vitamin D daily or a placebo.
The research was part of a comprehensive vitamin D study called VITAL. Funded by the National Institutes of Health, it began after a panel of experts 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. Expert panel members were asked to set a minimum daily requirement for the vitamin, but found that most of the clinical studies that had looked at the issue were inadequate and questioned whether the claims that vitamin D improved health were true be.
The prevailing opinion at the time was that vitamin D could prevent bone fractures. The researchers thought that when vitamin D levels fell, parathyroid hormone levels would rise at the expense of bones.
dr Rosen said these concerns led him and the other members of the National Academy of Medicine’s expert panel to set what he called an “arbitrary value” of 20 nanograms per milliliter of blood as a target for vitamin D levels and give people a shot advise reaching this 600 to 800 international units of vitamin D supplements to achieve this goal.
Laboratories across the United States then arbitrarily set 30 nanograms per milliliter as the cut-off for normal vitamin D levels, a level so high that almost everyone in the population would be considered vitamin D deficient.
The suspected relationship between vitamin D and parathyroid levels has not held up in later research, said Dr. roses. But uncertainty lingered, so the National Institutes of Health funded the VITAL study to get solid answers about vitamin D’s relationship to health.
The first part of VITAL, published earlier, found that vitamin D did not prevent cancer or cardiovascular disease in study participants. It also prevented falls, improved cognitive function, reduced atrial fibrillation, altered body composition, reduced migraine frequency, improved strokes, protected against macular degeneration or relieved knee pain.
Another large study in Australia found that people who took the vitamin did not live longer.
dr JoAnn Manson, director of preventive medicine at Harvard Medical School’s Brigham and Women’s Hospital and leader of the VITAL main study, said the study was so large that it included thousands of people with osteoporosis or with vitamin D levels in what is considered a low range included or “insufficient”. This allowed the investigators to determine that they also received no fracture reduction benefit from the supplement.
“This will come as a surprise to many,” said Dr. manson “But we only seem to need small to moderate amounts of the vitamin for bone health. Larger amounts do not bring greater benefit.”
The first 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 an advantage.
However, she cautioned that the study did not address the question of whether people with osteoporosis or low bone mass who are about to develop the disease 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 follow them in her own practice.
dr Dolores Shoback, an osteoporosis expert at the University of California, San Francisco, will continue to advise people 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 “does little or no harm and may have benefits,” he would still advise his patients with osteoporosis to take it and recommend the 600 to 800 Units per day in the National Academy of Medicine report.
“I will still tell my family and friends who don’t have osteoporosis to take a daily multivitamin to make sure they don’t become vitamin D deficient,” he said.
dr Khosla follows that advice himself. Many multivitamin tablets now contain 1,000 units of vitamin D, he added.
But dr Cummings and Dr. Roses remain adamant, even challenging the idea of vitamin D deficiency for healthy people.
“If vitamin D doesn’t help, then what is vitamin D deficiency?” asked Dr. Cummings. “That means you should take vitamin D.”
and dr Rosen, who signed the National Academy of Medicine report, has become a therapeutic vitamin D nihilist.
“I don’t believe in 600 units anymore,” he said. “I don’t think you should do anything.”