People who tested positive for COVID-19 had lower Vitamin D levels on average than people who tested negative, according to a massive peer-reviewed Israeli study published in the FEBS Journal.

The study found that the average plasma Vitamin D level – or the level of vitamin D in the liquid part of the blood – was 19.00 nanograms per mililitre (ng/mL) in 782 individuals that tested positive for COVID-19, compared to an average of 20.55 ng/mL in 7,025 individuals who tested negative for the virus. The study was conducted on a cohort of patients who were part of Leumit Health Services.

However, some experts urge caution in reading too much into the study’s findings, saying that other factors may explain the relationship observed in the study.

Still, low plasma Vitamin D was associated with a higher risk of COVID-19 infection and hospitalization, even after taking preexisting conditions, socioeconomic status, age, and gender into account, according to the study. In COVID-19 patients who were hospitalized, the average plasma vitamin D level was even lower at 178.38 ng/mL.

Vitamin D could act like a steroid, study author Milana Frenkel-Morgenstern of Bar Ilan University told the Times of Israel. Some steroids, such as dexamethasone, have been shown in clinical studies to improve outcomes for patients facing more serious COVID-19 disease.

Frenkel-Morganstern encouraged the government to maintain adequate outdoor spaces so that people could get sunlight, which is absorbed through the skin and helps the body make Vitamin D. The vitamin has been associated with a wide variety of health benefits, including maintaining bones and regulating calcium levels in the body.

However, others have said that it is too early to tell whether Vitamin D actually reduces the risk of COVID-19 infection. For example, people who get more exercise could have higher Vitamin D levels, and it could ultimately be exercise that is impacting COVID-19 risk, according to Ella Sklan, head of a molecular virology lab at Tel Aviv University.

And proving whether Vitamin D has any benefits as a potential treatment against COVID-19 requires clinical trials. The World Health Organization did not comment on whether Vitamin D would be considered a candidate for its massive Solidarity clinical trials testing potential COVID-19 treatments at the time of publication.

However, maintaining a healthy diet, and supplementing diets with appropriate vitamins is a “positive way to keep oneself healthy,”  and keeping healthy allows the body to help fight infectious diseases, according to a WHO statement.

“In situations where individuals’ vitamin D status is already marginal or where foods rich in vitamin D (including vitamin D-fortified foods) are not consumed, and exposure to sunlight is limited, a vitamin D supplement in doses of the recommended nutrient intakes (200-600 IU, depending on age) or according to national guidelines may be considered,” added the statement.

This story was updated 30 July to include the WHO’s statement

Image Credits: Flickr: Filip Patock.