Vitamin D May Help Reduce Long COVID Risk, Study Suggests

According to the World Health Organization (WHO), about every six in 100 people who have COVID-19 go on to develop post-COVID-19 condition, also known as long COVID .

Previous research shows that long COVID symptoms can last from 3 months to as long as a few years. Common symptoms of long COVID include constant fatigue , respiratory problems like a chronic cough or shortness of breath , “ brain fog ,” sleeping issues , headache , digestive issues like diarrhea and stomach pain , joint pain , depression , and anxiety .

There is currently no cure for long COVID. Symptoms are managed through medications and treatments for specific symptoms, such as physical therapy , cognitive rehabilitation , pulmonary rehabilitation , and mental health interventions .

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.

Past studies show that certain lifestyle choices, such as maintaining a healthy body weight , being physically active , prioritizing sleep , and avoiding smoking , may help reduce a person’s long COVID risk.

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.