Observational studies have reported an association between low levels of vitamin D and the susceptibility to acute respiratory tract infections, as vitamin D modulates the response of white blood cells to prevent them from releasing too many inflammatory cytokines. COVID-19 is known to cause an excess of pro-inflammatory cytokines, meaning the findings may be useful in the battle against the virus.
Recent studies from Italy and Spain (both experienced high COVID-19 mortality rates) have shown that both countries have lower than average vitamin D levels than most Northern European countries which is partly due to people, particularly the elderly, avoiding the strong sun and skin pigmentation reducing the natural vitamin D synthesis.
Northern Europe has been found to have the highest average levels of vitamin D due to the consumption of cod liver oil, supplements, and possibly less sun avoidance; Scandinavian nations are among the countries with the lowest mortality rates due to this virus per head of population in Europe.
According to Dr. Lee Smith, of Anglia Ruskin University, “We found a significant crude relationship between average vitamin D levels and the number COVID-19 cases, and particularly COVID-19 mortality rates, per head of population across the 20 European countries. Vitamin D has been shown to protect against acute respiratory infections, and older adults, the group most deficient in vitamin D, are also the ones most seriously affected by COVID-19.”
“A previous study found that 75% of people in institutions, such as hospitals and care homes, were severely deficient in vitamin D. We suggest it would be advisable to perform dedicated studies looking at vitamin D levels in COVID-19 patients with different degrees of disease severity,” adds Dr. Smith.
“Our study does have limitations however, not least because the number of cases in each country is affected by the number of tests performed, as well as the different measures taken by each country to prevent the spread of infection. Finally, and importantly, one must remember correlation does not necessarily mean causation;” notes Mr Petre Cristian Ilie, lead urologist of Queen Elizabeth Hospital King’s Lynn NHS Foundation Trust.
