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 intestine to absorb calcium, which the bones need to grow and stay healthy.
But now, in the first large randomized controlled study in the United States, funded by the federal government, researchers are reporting 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, hold true for people with osteoporosis and even those whose blood tests found them deficient in vitamin D.
These findings followed other findings from the same study that found no support for 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 perform more than 10 million vitamin D tests each year, an editorial published with the journal offers some advice: Stop.
“Providers should stop testing 25-hydroxyvitamin D levels or recommending vitamin D supplements and people should stop taking vitamin D supplements in order to prevent major illnesses or prolong life,” wrote the Dr. Steven R. Cummings, researcher at California Pacific. Medical Center Research Institute, and Dr. Clifford Rosen, Principal Investigator at Maine Medical Research Institute. Dr. Rosen is editor of 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 are sun deprived and may not not get minerals from foods regularly supplemented with vitamin D, such as cereals and dairy products.
Getting into such a severe state of vitamin D deficiency is “very hard to do in the general population”, Dr Cummings said.
Both scientists know that by making such strong statements, they are attacking vitamin vendors, testing labs and advocates who have claimed 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 vitamin D levels as part of routine blood tests.
The study involved 25,871 participants – men aged 50 and over and women aged 55 and over – who were required to take 2,000 international units of vitamin D each day or a placebo.
The research was part of a comprehensive vitamin D study called VITAL. It was funded by the National Institutes of Health and started after a panel of experts convened by what is now the National Academy of Medicine, a nonprofit organization, looked at the health effects of supplements. of vitamin D and found little evidence. The members of the expert panel were supposed to propose a minimum daily requirement for the vitamin, but found that most clinical trials that had studied the subject were inadequate, leading them to wonder if there was a part of truth in claims that vitamin D improves health.
The prevailing opinion at the time was that vitamin D was likely to prevent bone fractures. Researchers thought that as vitamin D levels decreased, parathyroid hormone levels would increase to the detriment of bone.
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 goal for vitamin D levels and to advise people to obtain 600 to 800 international units of vitamin D supplements to achieve this goal.
Laboratories in the United States then arbitrarily set 30 nanograms per milliliter as the threshold for normal vitamin D levels, a reading so high that almost everyone in the population would be considered vitamin D deficient.
The alleged relationship between vitamin D and parathyroid levels has not been confirmed in subsequent research, Dr. Rosen said. But uncertainty remained, so the National Institutes of Health funded the VITAL trial to get solid answers about the relationship between vitamin D and health.
The first part of VITAL, published previously, found that vitamin D did not prevent cancer or cardiovascular disease in trial participants. It also did not prevent falls, improve cognitive functioning, reduce atrial fibrillation, alter body composition, reduce the frequency of migraines, improve stroke outcomes, protect against macular degeneration, or reduce neck pain. knee.
Another large study, in Australia, found that people taking the vitamin did not live longer.
Dr. JoAnn Manson, chief of preventive medicine at Harvard Medical School’s Brigham and Women’s Hospital and head of the main VITAL trial, said the study was so large it included thousands of people with osteoporosis. or with vitamin D levels in a range considered low. or “insufficient”. This allowed the investigators to determine that they also received no fracture reduction benefit from the supplement.
“It will surprise many,” Dr. Manson said. “But we seem to only need low to moderate amounts of the vitamin for bone health. Larger amounts don’t confer greater benefits.
The bone study’s first author and principal investigator, Dr. Meryl S. LeBoff, an osteoporosis specialist at Brigham and Women’s Hospital, said she was surprised. She expected an advantage.
But she warned the study did not address whether people with osteoporosis or low bone mass just before the disease should take vitamin D and calcium, as well as osteoporosis medication. . 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 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, 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 osteoporosis patients to take it, recommending 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 have vitamin D deficiency,” he said. .
Dr. Khosla follows this advice himself. Many multivitamin tablets now contain 1,000 units of vitamin D, he added.
But Dr. Cummings and Dr. Rosen stand firm, even questioning the very idea of vitamin D deficiency in healthy people.
“If Vitamin D Doesn’t Help, What Is Vitamin D Deficiency?” asked Dr. Cummings. “It implies that 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 says. “I don’t think you should do anything.”