Can Taking Vitamin D Keep You From Getting Sick? What New Research Reveals Here's what new research found and what to know about vitamin D
Supplementing with the sunshine vitamin might not help you prevent a cold, after all
- A new study found that vitamin D supplementation offered no statistically significant protection against acute respiratory infections.
- Vitamin D may be helpful for protecting some groups of people, but researchers say it’s difficult to study it in isolation.
- Other healthy lifestyle habits might be more effective for warding off the common cold.
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Taking vitamin D to fend off the common cold might not be as effective as previously believed. A new analysis published in The Lancet found that vitamin D supplementation didn't provide statistically significant protection against the development of acute respiratory infections—aka the coughing, sneezing, and runny nose you might experience with a cold.
According to the Centers for Disease Control and Prevention, vitamin D is the second most commonly taken dietary supplement in the United States after multivitamins. Many believe supplementing with this fat-soluble nutrient, present in only a few foods and well absorbed from the sun, is key to preventing your run-of-the-mill illness.
Historically, this belief has had some scientific backing. A 2021 meta-analysis conducted by the same research team, for example, found a “modest protective effect” of taking vitamin D daily to ward off respiratory infections.
In the latest study, researchers aimed to review the science again, this time including more recently published papers.
“There’s lots of evidence that vitamin D influences the immune system, and many people have low vitamin D levels,” study author Carlos A. Carmago, Jr., MD, professor of epidemiology at Harvard T.H. Chan School of Public Health, told Health. We wanted to know, he added, “Would giving a vitamin D supplement help?”
The Latest Findings on Vitamin D and the Common Cold
Carmago and the other researchers added six additional studies for this new systemic review and meta-analysis, bringing the total number of studies and participants to 46 and over 64,000, respectively.
The scientists examined whether people who took any vitamin D were less likely to get acute respiratory infections than those who took a placebo and whether additional factors like age, dosage, or pre-existing blood levels of vitamin D made any difference. They then analyzed this information using a statistical method called a random-effects model.
The results? Taking vitamin D didn’t significantly lower people’s chances of contracting a cold, no matter where they fell on the spectrum of age, dosage, or existing vitamin D status. (Fortunately, however, vitamin D also did not cause any more side effects than a placebo.)
According to pulmonologist Neil W. Schluger, MD, dean of the School of Medicine at New York Medical College, who was not involved with the study, these results aren’t surprising.
“Although the prior (2021) review suggested a small benefit in preventing acute respiratory tract infections from vitamin D supplementation, that finding just barely reached statistical significance,” he pointed out in an email. “With the addition of several large, recent randomized controlled trials to the review, there is no longer evidence of a statistically or clinically significant reduction in the risk of acute respiratory infection (common colds but also bronchitis and pneumonia) in persons taking supplementation.”
Schluger added that, despite widespread attention around vitamin D for respiratory illness, the largest and most well-conducted randomized controlled trials have generally not shown a benefit of taking it for this purpose.
Carmago said, however, that his team’s research paints a complex picture of vitamin D’s effects on respiratory infections. “Looking at all vitamin D regimens as one intervention is challenging,” he said. For example, people with low baseline vitamin D levels might receive an immune health benefit from a frequent, low-dose supplement. But if other populations don’t, this drives the overall result toward the “null,” making it not statistically significant.
“Many people want to know if vitamin D supplements ‘work’ as a yes or no question—but the answer is ‘it depends,’” he said.
What to Consider Before Taking Vitamin D
Although vitamin D supplements might not be a panacea for cold prevention, it’s important to know that having adequate levels of the nutrient is still critical for good health. In addition to supporting immune function, vitamin D is essential for bone and neuromuscular health and can help reduce inflammation.
While it's always best to ask your healthcare team whether vitamin D is worth taking for your specific health concerns, Darby said that some people might benefit from supplementation. For example, it might be helpful for those living in a climate that doesn’t get much sun, who might be deficient in vitamin D as a result. People with osteoporosis may also need an added dose of vitamin D.
You can also boost your consumption through diet. “Most people can reach their vitamin D needs with fortified foods,” Darby said, noting that it’s important to also pay attention to diet quality and diversity. Look for milk, cereal, orange juice, and breads fortified with this nutrient, or reach for fatty fish as a natural source of vitamin D.
Evidence-Based Ways to Prevent a Cold
There’s no silver bullet for keeping respiratory infections at bay. However, certain lifestyle habits can impact your immune system’s ability to hold them off.
“Maintaining a healthy diet, avoiding tobacco use, and staying up to date on recommended vaccinations for viruses and bacteria that cause pneumonia are the best ways to avoid respiratory infections,” Schluger says.
As for loading up on supplements, though, he advises approaching with caution. “Many people take vitamins and supplements, but there is little evidence for health benefits of any kind unless a physician has identified a specific vitamin deficiency.”
This story originally appeared on: Health News - Author:Sarah Garone
