A large number of COVID-19 cases and high death rates could be related to vitamin D deficiency, a study has found.
Past studies have suggested that low status of vitamin D increases the likelihood of respiratory tract infections.
Vitamin D is crucial for immediate immune response through adjusting white blood cell reaction and reducing their production of cytokines.
Inflammatory cytokines are signalling molecules secreted from immune cells to promote inflammation.
An overload of cytokines would make a disease worse, as it is pro-inflammatory.
The COVID-19 virus triggers the body’s defence system, resulting in an extreme production of pro-inflammatory cytokines.
Researchers tracked data across 20 countries in Europe and found that vitamin D can help prevent coronavirus disease and death.
Older people are at the most risk of COVID-19 infection and the study shows that this age group across countries such as Italy, Switzerland, and Spain are seriously deficient in vitamin D.
Low levels of vitamin D in southern Europe seems to be related to factors such as avoiding strong sun and preferring the shade, and skin pigmentation, which reduces the synthesis of natural vitamin D.
Conversely, vitamin D levels are higher in Northern Europe as a result of vitamin D supplements, cod liver oil intake, vitamin D fortification of milk and dairy products in countries like Sweden and Finland, and less avoiding of the sun.
These may be a factor in Scandinavians being among the countries with the least cases of coronavirus and lowest death rates per capita.
Dr Lee Smith, study lead author, said:
“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.”
The study was published in Aging Clinical and Experimental Research (Ilie et al., 2020).