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Research Uncovers Promising Vitamin D Link to Long Covid Symptoms

August 24, 2026 by Logan Hamilton

Vitamin D supplements did not reduce COVID-19 severity or spread.
Image courtesy of Pexels.

Sometimes important answers appear in unexpected and surprising places. People often find lost items hidden under cushions or inside drawers. Researchers discovered a similar surprise while studying vitamin D and COVID-19.

Scientists found regular vitamin D intake may reduce Long COVID risk. This finding came from researchers at Mass General Brigham. Their results were published in the Journal of Nutrition.

How Did Research Find the Link?

Earlier studies explored vitamin D because it supports immune system function. However, past research linking vitamin D and COVID-19 showed unclear results. Researchers designed this study to better understand that relationship.

They created the VIVID trial to study vitamin D and COVID-19. The study included adults recently diagnosed with COVID-19 and their families. Participants came from both the United States and Mongolia.

A total of 1,747 adult participants were included in the analysis. Additionally, 277 family members joined the study under separate conditions. These family members received either vitamin D3 supplements or a placebo daily.

Participants took supplements or a placebo for a period of four weeks. Most participants began supplementation about three days after testing positive.

The United States trial ran from December 2020 through September 2022. The Mongolia portion ran from September 2021 through April 2022.

Researchers used randomization to reduce bias across the study groups. They also adjusted for factors that could influence results. These included age, sex, body mass index, race, and ethnicity. Vaccination status was also considered as a possible influencing factor.

The study found no meaningful change in COVID-19 symptom severity. It also showed no reduction in the likelihood of virus transmission.

However, researchers noticed a possible connection to Long COVID outcomes. Participants taking vitamin D showed a slightly lower risk of symptoms.

These long-term symptoms were measured eight weeks after initial infection. Participants taking supplements had a 21 percent chance of symptoms. Those taking a placebo had a 25 percent chance of symptoms.

This represents a 4 percent reduction in Long COVID risk. The difference was considered barely statistically significant by researchers.

What’s Next?

Even so, the findings remain important for future investigation efforts. Long COVID can cause wide-ranging and serious long-term health effects.

Because of this, even small improvements may have meaningful impacts. Researchers believe this signal could guide future clinical studies.

Further research will help confirm whether vitamin D truly reduces risk. Scientists will need larger studies and stronger statistical evidence. For now, the findings offer a cautious but promising direction forward.

Conclusion

Vitamin D supplements did not reduce COVID-19 severity or spread. However, participants showed a small decrease in Long COVID risk. Researchers say more studies are needed to confirm these early findings.

Have an upcoming trip? Passport Health offers a wide variety of options to help keep you safe from disease, including vaccines. Call or book online to schedule your appointment today.

Logan Hamilton is a health and wellness freelance writer for hire. He’s passionate about crafting crystal-clear, captivating, and credible content that elevates brands and establishes trust. When not writing, Logan can be found hiking, sticking his nose in bizarre books, or playing drums in a local rock band. Find him at loganjameshamilton.com.

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