Taking vitamin D supplements daily doesn’t help a person prevent bone fractures, a large study suggests — contradicting years of medical advice that claimed otherwise.
Researchers led by Harvard Medical School in Boston, Massachusetts, found that people who took the supplements were no less likely to have broken bones than those who didn’t.
Their results go against years of doctors telling patients to take the pills to promote calcium absorption and make bones stronger. About a third of American adults over the age of 60 already take the pills every day.
Some scientists not involved in the study said it showed people “shouldn’t be popping vitamins left and right.” But others cautioned that it didn’t show that people with osteoporosis should stop taking the vitamin.
The chart above shows the number of fractures recorded in the group that took vitamin D (left) and the number that took the placebo or dummy pill (right). It shows that there was no difference between the two groups, despite one increasing vitamin levels. Scientists said this should ‘rest’ any idea that vitamin D alone can make bones stronger
The study — published Thursday in the New England Journal of Medicine — recruited 26,000 participants from the general population.
It was not limited to people with vitamin D deficiency, low bone density, or high risk of fractures. But testing showed that thousands of participants at the start of the study had what would be considered low or insufficient vitamin D levels.
The participants were almost evenly distributed by gender with a mean age of 67 years. About 20 percent were black, which may be more at risk for low vitamin D levels because dark skin reduces the amount of sunlight the body absorbs, which is essential for making the vitamin.
What is vitamin D and how do I get it?
Vitamin D is a type of vitamin that the human body both obtains from food and produces when exposed to sunlight.
What does it do?
It helps regulate the amount of calcium and phosphate in the body.
These nutrients are needed to keep bones, teeth and muscles healthy.
People who do not get enough vitamin D can develop bone disorders such as rickets in children and osteomalacia (a softening of the bones) in adults.
How do I get enough vitamin D?
In the US, most people get the vitamin D they need from sunlight between April and September, as long as they go outside.
The body naturally produces vitamin D when it is exposed to sunlight.
Vitamin D is also found in foods such as oily fish, liver and egg yolks.
Should I take a supplement?
Doctors say people should consider taking a vitamin D supplement in the winter month, when sunlight is weaker.
Other people may need vitamin D all year round because they are housebound, or if they have dark skin, which reduces the amount of sunlight their skin absorbs.
Children ages one to four should also receive a 10-microgram (µg) vitamin D supplement daily throughout the year.
What happens if I take too much?
Taking too much for a long time can lead to a dangerous build-up of calcium in the body, which can weaken the bones and also damage the heart and kidneys.
Doctors recommend taking no more than 800 international units (IUs) per day.
Vitamin D is often sold in units called IU. One microgram of vitamin D is equal to 40 IU.
In the study, participants were given vitamin D3 pills every day. This is a type used in many supplements because it is easier for the body to absorb.
They were then followed for five years and questioned annually to see if they were still taking the pills or had suffered a fracture.
Half took supplements containing up to 800 International Units (IU) of vitamin D, which was the upper limit of the recommended daily allowance.
The rest received a placebo.
The results showed that there was no difference in the number of fractures recorded in both groups.
Among those who received vitamin D, 769 of the 12,927 participants had fractures — equivalent to six percent.
And for those who received the placebo, 782 of the 12,944 suffered fractures — also six percent.
Fractures were recorded on the pelvis, wrist, hips and other areas.
dr. Meryl LeBoff, the skeletal health expert who led the study, and colleagues wrote in the paper, “Vitamin D3 supplementation did not result in a significantly lower risk of fracture than placebo in generally healthy midlife and older adults.”
The study is the first large randomized controlled trial to examine the effects of vitamin D, and marks the latest blow to suggestions it may help strengthen bones in otherwise healthy adults.
Initially, the researchers — who were funded by the government — set out to investigate the optimal intake of vitamin D per day.
Since 2011, the National Academy of Medicine — now the National Institutes of Health — had told people to get up to 800 IU a day to prevent bone fractures.
The Centers for Disease Control and Prevention (CDC) had also recommended vitamin D to help with bone health.
But upon review, the scientists found that most studies suggesting vitamin D supplements were “inadequate,” leaving them at the center of whether the pills are really necessary.
Write in a editorial dr. Steven Cummings, a top osteoporosis expert at the University of California, San Francisco, said his findings should “calm down” any idea that vitamin D supplements alone can prevent fractures.
“Providers should stop… recommending vitamin D supplements, and people should stop taking vitamin D supplements to prevent serious illness or prolong life,” he said.
Over the years, successive studies have been conflicting as to whether the supplements are helpful — with many failing to show whether vitamin D is really good for bone health.
The latest study is reliable because of the large sample size and high adherence among participants.
But it doesn’t show whether people with a vitamin D deficiency benefit from the pills.
dr. Ethel Siris, an endocrinologist at Columbia University Medical Center in New York who was not involved in the study, said it had a big impact.
She said NBC“The takeaway is that people in general shouldn’t be popping vitamins left and right. If you’re trying to prevent fractures, vitamin D alone isn’t enough.
“But an adequate intake of calcium and vitamin D remains, in my view, a necessary part of the treatment of people with osteoporosis.”