The idea made so much sense that it was accepted almost without question: Vitamin D pills could protect bones from fractures. After all, the body needs the vitamin so that the intestines can absorb calcium, which the 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 had no effect on bone fracture rates. The results, published Thursday in The New England Journal of Medicine, hold true for people with osteoporosis and even those whose blood tests show vitamin D deficiency.
These results followed other conclusions from the same study that found no support for a long list of purported benefits of vitamin D supplementation.
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 with the paper has some advice: Stop.
“Providers should stop testing 25-hydroxyvitamin D levels or recommending vitamin D supplements, and people should stop taking vitamin D supplements to prevent serious disease or prolong life,” Dr. Stephen wrote R. Cummings, a researcher at the California Pacific Research Institute of the Medical Center and Dr. Clifford Rosen, a senior scientist at the Maine Institute for Medical Research. Dr. Rosen is an editor at The New England Journal of Medicine.
They say there are exceptions: people with conditions like celiac disease or Crohn’s disease need vitamin D supplements, as do those who live in conditions where they are deprived of sunlight and may not get any of the mineral from food , which are routinely supplemented with vitamin D, such as cereals and dairy products.
Getting into such a severe state of vitamin D deficiency is “very difficult for the general population,” Dr. Cummings said.
The two scientists know that by making such strong statements, they are pitted against vitamin sellers, testing labs and advocates who claim that taking vitamin D, often in massive amounts, can cure or prevent a wide variety of diseases and even help people live longer.
Doctors often check vitamin D levels as part of routine blood tests.
The study included 25,871 participants — men aged 50 and over and women aged 55 and over — who were assigned to take 2,000 international units of vitamin D each day or a placebo.
The study is part of a comprehensive vitamin D study called VITAL. It was funded by the National Institutes of Health and started after an expert panel convened by what is now the National Academy of Medicine, a nonprofit organization, studied the health effects of vitamin D supplements and found little evidence. The panel members had to come up with a minimum daily requirement for the vitamin, but found that most of the clinical studies that examined the topic were inadequate, leading them to question whether there was any truth to the claims that vitamin D improves health.
The prevailing opinion at the time was that vitamin D probably prevented bone fractures. Researchers believe that when vitamin D levels drop, parathyroid hormone levels will rise to the detriment of bone.
Dr. Rosen said those concerns led him and other members of the National Academy of Medicine panel to set what he called an “arbitrary value” of 20 nanograms per milliliter of blood as a target for vitamin D levels and to advise people to receive 600 to 800 international units of vitamin D supplementation to achieve this goal.
Laboratories in the United States then arbitrarily set 30 nanograms per milliliter as the cutoff point for normal vitamin D levels, a reading so high that almost everyone in the population would be considered vitamin D deficient.
The hypothesized link between vitamin D and parathyroid levels has not been sustained in subsequent research, Dr. Rosen said. But uncertainty persists, so the National Institutes of Health funded the VITAL study to get some solid answers about vitamin D’s connection to health.
The first part of VITAL, published earlier, found that vitamin D did not prevent cancer or cardiovascular disease in study participants. Nor does it prevent falls, improve cognitive functioning, reduce atrial fibrillation, change body composition, reduce migraine frequency, improve stroke outcomes, protect against macular degeneration, or reduce knee pain.
Another large study in Australia found that people taking the vitamin did not live longer.
Dr. JoAnn Manson, chief of preventive medicine at Brigham and Women’s Hospital at Harvard Medical School and leader of the pivotal VITAL study, said the study was so large that it included thousands of people with osteoporosis or with vitamin D levels in a range considered for low or “not enough”. This allowed the researchers to determine that they also did not receive a fracture reduction benefit from the supplement.
“This will surprise many,” Dr. Manson said. “But it seems we only need small to moderate amounts of the vitamin for bone health. Larger amounts do not bring greater benefits.
The first author and principal investigator of the bone study, Dr. Meryl S. LeBeouf, an osteoporosis expert at Brigham and Women’s Hospital, said she was surprised. She expected a benefit.
But she cautioned that the study did not address the question of whether people with osteoporosis, or low bone mass, less than the condition, should take vitamin D and calcium along with osteoporosis drugs. Professional guidelines say to take vitamin D and calcium, and she will continue to follow them in her own practice.
Dr. Dolores Shobak, 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 is “a simple intervention 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 because vitamin D “will do little or no harm and may have benefits,” he will continue to advise his osteoporosis patients to take it, as recommends 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 multivitamin a day to make sure they don’t get vitamin D deficient,” he said.
Dr. Khosla himself follows this advice. Many multivitamin tablets now contain 1,000 units of vitamin D, he added.
But Dr. Cummings and Dr. Rosen remain adamant, 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 means you need to take vitamin D.”
And Dr. Rosen, who signed the National Academy of Medicine report, 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.”
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