Mar 16, 2026
3 min read
Vitamin D supplements can reduce the risk of long-term COVID by 4%, according to a Mass General Brigham study.Dr. Joanne Manson reports promising results in a clinical trial with 1,747 participants.
Vitamin D supplements may offer researchers new clues about lingering COVID symptoms that persist after infection, according to a new study.
Mass. researchers investigated.Brigham General whether high doses of vitamin D could affect the outcome of COVID-19, including the risk of developing chronic COVID-19, a condition with symptoms such as fatigue, shortness of breath and brain fog weeks or months after initial infection.
The results were published in the Journal of Nutrition.
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The randomized clinical trial included 1,747 adults and 277 household members who had recently tested positive for COVID-19.Participants were assigned to take vitamin D3 supplements or a placebo for four weeks.
Dr. JoAnn Manson, the study's lead author and a Brigham, Mass. General physician, told Fox News Digital that the results suggest a possible benefit related to long-term symptoms.
"The main finding is that vitamin D supplementation appears to be promising for reducing the risk of developing persistent COVID-19, but does not affect the severity of acute infection," Manson said.
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Researchers found that vitamin D supplementation did not significantly change short-term outcomes such as symptom severity, hospital visits or emergency care.
The study also showed no difference between the vitamin D and placebo groups in the likelihood of household contacts becoming infected with the virus.
However, when the researchers analyzed the participants who closely followed the supplement regimen, they noticed a potential difference in long-term symptoms.
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About 21 percent of participants who took vitamin D reported at least one persistent symptom eight weeks after infection, compared with 25 percent of those who received a placebo.
"There is a lot of interest in whether vitamin D supplementation can help with COVID, and this is one of the largest and most rigorous randomized trials on the subject," Manson said in a press release.
"Although we did not find that high levels of vitamin D reduced the severity of COVID-19 or hospitalizations, we did see promising signs of prolonging the duration of COVID-19 that warrant further study," he added.
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Manson said vitamin D may contribute to long-term complications because the nutrient plays a role in regulating inflammation in the body.
The researchers noted several limitations of the test.The study had to be conducted far into the pandemic, and the participants started taking vitamin D a few days after their COVID diagnosis.
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Ideally, Manson said, supplementation would begin before infection or shortly after diagnosis.
He added that larger studies will be needed to confirm whether vitamin D can reduce the risk or severity of long-term COVID symptoms.
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The researchers are planning more trials to see if vitamin D can help treat people who have had COVID for a long time.
