A recently published paper considers the role of vitamin D in the outcome of Covid-19 cases.
One mostly overlooked factor that could influence outcome of COVID-19 is the relative vitamin D status of populations, says the author.
Whether low vitamin D levels are a cause or consequence of disease remains a point of heated debate. Intervention trials have rarely shown benefits of vitamin D supplementation as treatments or preventive measures.
However, there appears to be one important exception to this generalisation: upper respiratory tract infections. A 2017 study that drew on 25 trials showed that vitamin D supplementation protected against acute respiratory tract infections in patients with very low vitamin D levels. The study found that Vitamin D supplementation resulted in a statistically significant reduction in the proportion of participants experiencing at least one acute respiratory tract infection.
In addition, some groups experiencing higher Covid-19 mortality, older people and those with darker skin, are also more likely to suffer from vitamin D deficiency.
Vitamin D seems to support antimicrobial activity in the respiratory epithelium, cells which line the lungs. And it might reduce the inflammatory response to infection with SARS-CoV-2. In addition, Vitamin D is known to interact with angiotensin-converting enzyme 2 (ACE2), which is used by SARS-CoV-2 to enter cells.
Rose Anne Kenny from Trinity College Dublin, who has led a number of studies on vitamin D, is adamant that the recommendations from all public health bodies should be for the population to take vitamin D supplements during this pandemic. “The circumstantial evidence is very strong”, she said. “We know vitamin D is important for musculoskeletal function, so people should be taking it anyway”.
Adrian Martineau, from Barts and Queen Mary University of London says: “At best vitamin D deficiency will only be one of many factors involved in determining outcome of COVID-19, but it’s a problem that could be corrected safely and cheaply; there is no downside to speak of, and good reason to think there might be a benefit”.
The NHS in the UK suggests considering taking 10 micrograms of vitamin D a day.
A study funded by the Swiss National Science Foundation (SNF) shows that Switzerland’s weak winter sunlight doesn’t provide a level of vitamin D anywhere close to the minimum recommended by the World Health Organisation (WHO). Another study estimates 40% of Switzerland’s population is deficient in vitamin D.
See full paper considering the role of vitamin D in the outcome of Covid-19 cases here.