Dr. Steven Cummings, a professor of medicine, epidemiology and biostatistics at University of California–San Francisco, has grown accustomed to what he describes as the “phases of enthusiasm” vitamins go through. First, there’s the halo effect — you take vitamins, because that’s what you do. “Because it’s a vitamin,” he says.
Then, he notes, observational studies reinforce the behavior: People who are found to be sick, for example, have depleted levels of vitamins — so the opposite must be true: Taking vitamins must make us healthier and less likely to develop disease. But then follow-up research taking a closer look, such as that evaluating what happens when vitamins are taken compared with a placebo, “almost always leads to disappointment and even realization that there’s risk,” says Cummings, who directs the San Francisco Coordinating Center, which designs and coordinates very large studies, including randomized controlled trials — considered a gold-standard in research; Cummings also has expertise in the causes and treatments of osteoporosis. “That sometimes takes 20 years to go through that cycle, and it looks like vitamin D is headed that same way.”
Doctors have long routinely advised older patients, who are more likely to have low vitamin D levels, to up their intake through supplementation. But in recent years, some experts have shifted to a more tepid, cautious approach, as the accepted benefits of vitamin D and the notion that many, if not most people, were deficient has been challenged. The Institute of Medicine declared in 2010 that the majority of Americans and Canadians are already getting enough vitamin D and calcium, while noting widespread confusion over how much vitamin D is necessary to ward off a deficiency. In addition to establishing new daily vitamin D and calcium intake recommendations, an IOM report also set upper limits on what’s considered safe.
A study published online in JAMA Internal Medicine in January found that, despite some previous indications that boosting vitamin D levels above IOM-recommended levels might reduce fall risk in seniors — and thereby decrease the likelihood of related injuries, like fractures — that turned not to be the case for patients ages 70 and older who were studied in the randomized clinical trial.
“Entering the trial, all 200 participants had fallen in the prior year,” said lead study author Dr. Heike Bischoff-Ferrari, chair of the Department of Geratrics and Aging Research at the University Hospital of Zurich and the University of Zurich in Switzerland, in an email. In fact, giving doses of vitamin D that exceeded the current recommendation of up to 800 international units per day or 24,000 IUs monthly — for example, giving patients 60,000 IUs of vitamin D per month — was associated with an increased risk of falls. “Higher percentages of participants … fell compared with the standard dose group,” Bischoff-Ferrari says. Upping vitamin D dosage has been proposed — and recommended by many physicians — as a way to reduce fall risk in older people who aren’t as steady on their feet, including to improve leg muscle strength.
Those in the standard dose group saw their fall risk drop. But while findings from the trial support low-dose over high-dose vitamin D supplementation, without a placebo group for comparison, the researchers note they couldn’t establish a benefit of low dose over placebo.
It wasn’t clear why high-dose vitamin D supplementation was associated with a higher rate of falls, but the researchers say it’s unlikely it was due to chance.
Bischoff-Ferrari remains steadfast that vitamin D supplementation at recommended levels remains an effective, safe way to treat deficiency and prevent falls. “The best way forward for seniors is to not be vitamin D deficient — and the safest way to avoid that is take 800 IU vitamin D daily or 24,000 IU monthly. This is important for bone and muscle health — and possibly for general health as well,” she says.
Cummings, who co-authored an editorial that accompanied the research Bischoff-Ferrari led, was more sparing, but agreed at least it seemed safe to do so: “There’s uncertainty whether supplements are valuable at all. But, in addition, avoid taking supplements with higher doses than the 800 [IU per day].”
Bischoff-Ferrari says there’s previous research to show that this level of vitamin D supplementation can help prevent falls for “community-dwelling” seniors — those who live independently in the community. But Cummings says it’s only been proven effective in this regard, in combination with calcium, for individuals in institutional settings, like nursing homes, where it’s presumed their diet is poorer and they’re not exposed to as much sunlight — two sources of vitamin D. “We know in that situation, the combination of calcium, vitamin D is very beneficial — needs to be given,” he says, adding that the evidence consistently shows that it reduces the risk of fracture — and probably mortality — “and that’s probably due to a decreased risk of falls.”
In advocating more broadly for vitamin D supplementation, Bischoff-Ferrari emphasizes that it would be nearly impossible to get enough vitamin D from dietary sources alone, like fish, and health experts vary on recommending sun exposure for seniors due to risks of skin cancer from over-exposure. She notes research finds about half the world’s population is vitamin D deficient. But where big claims about the health benefits of vitamin D have fallen away under closer scrutiny — it hasn’t been proven to prevent heart disease and cancers, for example, Cummings points out, as once widely believed — others are more “meh” about vitamin D supplementation.
“There was quite a push to have people take supplements to raise their serum levels of vitamin D, but I think we’re now getting more and more data that there’s really a middle level that’s optimal, and going above that is not improving the situation,” says Catharine Ross, professor of nutrition at Penn State, who chaired the IOM committee that set dietary intake levels for calcium and vitamin D. Due to things like vitamin-fortified foods, people are consuming higher levels of vitamins, where current recommendations find about 600 IUs meets the needs of most people — including to promote skeletal growth and bone health — though individuals over age 70 may need up to 800 IUs. “I doubt that a supplement is really necessary. But if one wants it as a kind of safety measure, then just stay at the recommended dietary intake level,” Ross says.
Up to 4,000 IUs is deemed the “safe upper boundary” — though experts stress that’s a limit, not a goal.
Even at doses below the recommended levels for vitamin D intake, Cummings notes research has found a small increase in the risk of kidney stones when vitamin D and calcium are given together. The IOM has also previously warned that excessive vitamin D can damage the kidneys as well as the heart, though studies on the long-term harms of vitamin D supplementation are lacking. In some case studies, Ross notes, where people inadvertently took very high, unsafe levels of vitamin D, there were changes in bone and fractures.
“The history of research in other vitamins should give people cause to pause, Cummings says; he stresses that it’s important to wait for research trials that compare any vitamin or pill with a placebo to prove benefit, before taking that vitamin supplement or medicine. “If there’s no benefit to taking something, as far as we know, and we don’t know about the harms — why do it?” That goes, too, for upping one’s daily dose of vitamin D above recommended levels, he says: “Why take a higher dose if so far there is no benefit?”
More from U.S. News
11 Changes Women Go Through in Menopause
Pharmacist Recommended Vitamins and Supplements
Do You Really Need a Vitamin D Supplement? originally appeared on usnews.com
