- About every six in 100 people who have COVID-19 go on to develop post-COVID-19 condition, dubbed ‘long COVID.’
- There is currently no cure for long COVID and anyone who is infected with the coronavirus that causes COVID-19 can develop it.
- Past studies show that certain lifestyle choices, such as following a healthy diet, may help reduce a person’s long COVID risk.
- A new study found that while vitamin D supplements may not reduce the severity of COVID-19, they may help reduce a person’s risk of developing long COVID.
Anyone who is infected with the coronavirus that causes COVID-19 can develop long COVID. However, older adults, those with severe COVID-19, and people with underlying health conditions are generally at a higher risk of developing long COVID.
Now, a new study published in The Journal of Nutrition has found that, while vitamin D supplements may not reduce the severity of a COVID-19 infection, they may help reduce a person’s risk of developing long COVID.
For this study, researchers recruited more than 1,700 adults in the United States and Mongolia who had recently tested positive for COVID-19, as well as 277 members of their household who came in contact with the infected individual.
Participants were randomly selected to receive either a daily vitamin D3 supplement or placebo for 4 weeks. The average time between a participant’s positive COVID-19 test and start of the vitamin D3 supplement or placebo was 3 days.
“Long COVID continues to impact the lives and quality of life of millions of people worldwide,” JoAnn Manson, MD, DrPH, chief of the Division of Preventive Medicine at Mass General Brigham, Michael and Lee Bell Professor of Women’s Health at Harvard Medical School, and senior author of this study, told Medical News Today.
“Research to date has provided few answers on causes, prevention, or treatment of long COVID,” Manson noted.
At the study’s conclusion, scientists found that study participants who kept to their vitamin D regimen demonstrated a signal that they were at a lower risk of developing long COVID symptoms at 8 weeks, when compared to those taking the placebo.
Additionally, of those in the vitamin D group, 21% reported at least one persistent symptom, while 25% did in the placebo group.
“Vitamin D is known to have favorable effects on immune health and to tamp down inflammation, which is believed to be a key driver of long COVID,” Manson explained. “It was surprising to us to see a signal for benefit against long COVID, given that the treatment period lasted only four weeks.”
“Our VIVID trial showed suggestive benefits of vitamin D for prevention of long COVID, which merits further study,” she added. “A larger randomized trial is necessary to provide greater statistical certainty.”
The researchers also noted that there was no difference between the vitamin D and placebo groups over a 4-week period when looking at rate of hospitalizations, clinic visits, ER trips, or deaths, and no significant difference was found in terms of COVID symptom severity between the two groups.
Additionally, taking high-dose vitamin D did not lower the rate at which household members contracted COVID-19.
“A key takeaway is that vitamin D supplementation looks promising for reducing the risk of developing long COVID, but does not appear to affect the severity of the acute infection,” Manson said.
“This is probably because vitamin D tamps down inflammation and prevents the longer-term complications of long COVID, but not symptoms that are already underway,” she added.
“These findings are consistent with our earlier findings in VITAL that vitamin D lowers biomarkers of inflammation — such as CRP (c-reactive protein) — and reduces the future risk of autoimmune disease but doesn’t affect symptoms that are already ongoing,” she continued.
“A recommendation would be to increase background intake of vitamin D during the winter or other periods when COVID and other viral infections become more prevalent. This may also reduce the risk of developing long COVID. We are planning an additional randomized trial to test high-dose vitamin D for treating the symptoms of long COVID.”
– JoAnn Manson, MD
MNT had the opportunity to speak with Fady Youssef, MD, a board-certified pulmonologist, internist and critical care specialist at MemorialCare Long Beach Medical Center in Long Beach, CA, about this study.
Youssef, who was not involved in the the research, commented that his first reaction to the research results was that the story of vitamin D remains somewhat unresolved.
“We’ve known for years that vitamin D seems to influence a number of health outcomes beyond bone health, but we still don’t fully understand the mechanisms or the circumstances in which it provides benefit,” he told us.
Hypothesizing on how vitamin D might be able to help reduce long COVID risk, Youssef noted that vitamin D plays a role in regulating immune responses and inflammation.
“One possibility is that adequate vitamin D helps the immune system resolve infection in a more balanced way, potentially reducing the lingering inflammation or immune dysregulation that many researchers believe contributes to long COVID,” he told us.
“It’s also possible that vitamin D affects metabolic and endothelial pathways that influence recovery after viral illness,” Youssef continued.
“Long COVID can significantly affect quality of life for months or even years, and we still lack clear diagnostic markers and a full understanding of the underlying biology,” he added. “Understanding what long COVID is and what causes it will inform future medical care and epidemic preparedness.”
