Vitamin D supplements have cultivated a bit of a reputation for their role in maintaining bone health. The promise was that popping a dose could help prevent fractures and tackle other diseases too. A new clinical trial though calls their purported benefits into question, showing that they may offer little or no added advantages for bone healthin healthy adults.

Published in the New England Journal of Medicine this week, the study details the findings of large-scale, randomized clinical trials on what vitamin D supplements can — and can’t do.

The researchers used data from an existing research project, the VITamin D and OmegA-3 TriaL (VITAL), which documented the health data of more than 25,000 adults over the age of 50. The clinical trial in itself had a different scope: it wanted to assess whether these supplements reduced the risk of cardiovascular disease and cancer among the participants. For a period of five years, the participants were asked to take vitamin D and omega-3 supplements or a placebo. This allowed the researchers to also measure other health outcomes, such as bone fractures.

Thus began deeper scrutiny of whetherpeople ages 50 and up were at lower risk of fractures if they added vitamin D alone in their regimen. The researchers compared the frequency of fractures in two groups: those taking supplemental vitamin D3 (a form of the vitamin that is easier for the body to absorb) and those who were given the placebo instead. Out of the 2,000 cases of bone fractures, those who were taking the supplement were not any more protected than the latter group. “No possible benefit was seen when looking more specifically at any of the different types of fracture we can get, such as hip or wrist fractures, nor was there any difference when accounting for factors like a person’s age, gender, or baseline weight,” explained Gizmodo.

Thus for healthy, older adults without any preexisting conditions, or who were not severely deficient in vitamin D, there was a lack of evidence around vitamin D supplements’ many benefits.

“The takeaway is that in general, people shouldn’t be popping vitamins left and right and if you’re trying to prevent fractures, vitamin D alone is not enough,” said Dr. Ethel Siris, an endocrinologist who works with osteoporosis patients at Columbia University Medical Center in New York, who was not involved with the trial.

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Do Multivitamins Really Make People Healthier?

Vitamin D is a magic bullet in the realm where culture meets science. Past research has illustrated that the vitamin allows for absorbing calcium and phosphorus from the foods we eat, and further decreases bone deterioration. But it has proven difficult to measure the vitamin’s effects in silos; studies have contradicted each other in examining the role of supplementing the body with vitamin D. One research showed that an excess of vitamin D levels with the help of supplements could be inimical to health.

The science around Vitamin D supplements builds on the contentious benefits of multivitamins in general. During the pandemic, multivitamins’ sales jumped as people scoured for any and every immunity booster. The pharma industry has leveraged the anxiety around wellness to frame supplements as the end-all and be-all of “good health.” The emergence then makes it necessary to contextualize the efficacy of these pills.

When it comes to vitamin D in general, experts note that people can get a healthy dose from their diets and exposure to the sun. Supplements then offer no added benefits and may even be unnecessary with the sole goal of bolstering bone health.

“In the context of reducing fractures, supplements won’t do much for most people,” said Connie Weaver, a distinguished research professor of nutrition science at San Diego State University, who was not involved in the study.

There are some important caveats to keep in mind. The findings do not apply to people with osteoporosis or those who have a low bone mass and severe vitamin D deficiency. “Most participants in the trial were not deficient and may have already reached the vitamin D level needed for bone health,” the researchers noted. In those cases, supplements have been proven to play a role, but vitamin D pills may still not be enough. Experts recommendexercise, extra doses of calcium and vitamin D, and dietary changes.

For a largely healthy adult population, however, a dose a day may not keep fractures — and other ailments — away. As Dr. Meryl S. LeBoff, lead author of the current study said, sometimes, “more is not better.”