Vitamin D has become synonymous with sunshine and strong bones, ever since the British scientist Edward Mellanby discovered its role in preventing rickets in 1919. Now it’s a standard supplement, added to everyday foods like milk and orange juice to prevent bendy bones. But in early October, a re-analysis of the effects of the popular vitamin sparked confusion and uproar. Vitamin D, it turns out, may not be the wonder compound it appears to be.
Mark Bolland, Ph.D., an associate medical professor at the University of Auckland in New Zealand, concluded after reviewing 81 recent studies spanning a total of 53,537 participants that vitamin D has no effect on preventing bone fractures or increasing bone mineral density, a measure of strength-conferring minerals like calcium in bones. Even the highest doses of vitamin D, he found, didn’t have any effect.
"Perhaps people aren’t interested in getting to the truth of the story.
In the week following its release in The Lancet Diabetes and Endocrinology together with a commentary by J. Chris Gallagher, MD, a professor of medicine at Creighton University who also studies vitamin D, his article prompted hot takes from news sites, scientists, and the authors of the studies involved in the review. Bolland, for his part, is merely trying to get to the truth, which is not always straightforward when it comes to supplements. The public wants to know whether or not they should take a thing. But the fact of the matter is that it’s not always clear. According to Bolland’s paper, adding more and more vitamin D to the average diet doesn’t continue to make bones stronger and stronger — especially for someone who is already doing fine in the vitamin D department.
“In the end, as a reader, we’re left with ‘What should we believe?’” Bolland tells Inverse, reflecting on the events of the past week. “It adds to the narrative that experts don’t agree. Perhaps people aren’t interested in getting to the truth of the story.”
The media was quick to raise the alert about the long-beloved vitamin. WebMD reported wrote that “a new study contends that claims of benefits from supplements of the ‘sunshine vitamin’ fall flat.” A headline on Forbes mused: “How well did Vitamin D fare? Is there a grade worse than a D?”
The surprising results of Bolland’s review struck a chord because vitamin D is ever-present in our lives. In some places it’s literally government-mandated: In the ]US and Canada](https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/), all infant formulas must contain between small amounts of vitamin D, and in Canada (where sunshine is less abundant) all milk is fortified by law. NIH guidelines, based on the National Academies of Sciences’ Food and Nutriton Board, recommend that men and women aged one through 70 take 600 IU or 15 micrograms of vitamin D every day to maintain bone health. With vitamin D supplements on the market that provide as many as 10,000 IU, meeting those guidelines is not that difficult.
But Bolland’s study, which shows that even that much additional supplementation is probably superfluous for the bones of healthy people, suggests that all of these guidelines are a waste of time.
Not long after the release of Bolland’s paper, the Guardian published three letters, penned by UK doctors, under the headline “Keep Taking The Vitamin D Tablets.” One of the letters argued that if everyone followed the advice of Bolland’s paper, some especially vulnerable populations, like infants and young children, would have an increased risk of developing vitamin D insufficiency, which can cause weak bones, seizures, and even heart failure.
Bolland and Gallagher admit that there are some people who do need vitamin D supplements more than others, but those populations are at least in part determined by geography.
"I thought that was an odd comment asking for more trials. How many more trials do you need?
“There are some people who need vitamin D, but that’s in people who are already low,” says Gallagher. “That’s not a problem we have in this country [the US] because dairy products are fortified with vitamin D. But if you go to Northern Europe, England, Scotland, Holland, lower levels of vitamin D are still quite common. So it’s still important to treat that population. Whereas here, with the craze — what I call the vitamin D craze — people are taking 5,000 units a day.”
In a critical write-up of Bolland’s paper, published in the British Medical Journal, some experts attacked the studies used in the review, recommending that more trials should be done before the world rethinks vitamin D. This seemed to be the final straw for Bolland, who responded with his own BMJ comment. “In fact, there are ample trial data to permit reliable conclusions,” he wrote.
“I thought that was an odd comment asking for more trials,” he says. “How many more trials do you need? The trials for falls and fractures — there’s more than 35,000 people in the trials today. I don’t think any more trials will be useful at all.”
From this tangled mess of back-and-forth, one thing is clear: vitamin D is having an identity crisis.
The Final Verdict
Bolland is sticking to his guns: For the most of us, he says, there’s no need to consume extra vitamin D. He’s confident that his statistical analysis is enough to settle this once and for all. Gallagher agrees with him on the power of this statistical evidence.
“I think it’s a definitive study,” Gallagher says. “The other point he makes is that it doesn’t matter how many more studies you do, it’s not going to change the results. And he does this with sophisticated statistical analysis.”
"Why don’t people believe the evidence that’s out there? It’s a very strange thing.
Bolland argues that we have all the data we need to draw conclusions about vitamin D and that if we were to redo existing studies, we’d likely see the same effect. Nevertheless, redundant studies are ongoing in Australia, England and throughout the United States, suggesting the science community is unwilling to accept it’s time to draw a line in the sand about vitamin D and bone health.
“Why don’t people believe the evidence that’s out there? It’s a very strange thing. I guess, wearing my research hat, it’s really disappointing,” Bolland laments.
“When you do clinical trials and the results of those clinical trials are clear, you expect people read it and think, ‘Well, that settles the question,’ and it hasn’t. So why is that? I think there are people who passionately believe that vitamin D will be beneficial even though it’s not.”
Is This The End of Vitamin D?
To be fair, a lot would change if vitamin D supplementation for bone health suddenly became a thing of the past. That said, its effects on other parts of human physiology remain to be studied, and Bolland and Gallagher have no problem with doing that.
“There are about a 100,000 people in trials at the current time, and some of these endpoints are heart disease and cancer and we need to see if vitamin D has an effect on these endpoints, say Gallagher. “All we can say from Bolland’s article is that there’s no effects on fractures and falls. We need to keep an open mind.”