New research from Trinity College Dublin and the University of Edinburgh has investigated the link between vitamin D and COVID-19 and found that residential ultraviolet B (UVB) radiation in the weeks leading up to COVID-19 infection provides strong protection against severe illness and death.
Connection between Vitamin D Deficiency and COVID-19
Previous studies have found an association between vitamin D deficiency and increased susceptibility to viral and bacterial respiratory infections. Similarly, several observational studies have found a strong association between vitamin D deficiency and COVID-19, but it could be that these effects are confounded and are actually the result of other factors, such as obesity, advanced age, or chronic diseases, which are also associated with low vitamin D levels.
To address this issue, researchers were able to calculate “genetically predicted” vitamin D levels that are not affected by other demographic, health, and lifestyle factors by using information from more than 100 genes that determine vitamin D status.
Mendelian randomization is a particular analytic approach that allowed researchers to use genetic data to examine whether there is a causal relationship between vitamin D and COVID-19. Few previous studies have attempted this but failed to demonstrate a causal relationship. This may be because they ignored UVB radiation from the sun, which is the main source of vitamin D for most people.
The researchers studied genetically predicted and UVB-predicted vitamin D levels together for the first time. Nearly half a million people in the United Kingdom participated in the study, and environmental UVB exposure prior to COVID-19 infection was assessed individually for each participant.
Comparing the two variables, the researchers found that the correlation with vitamin D concentration measured in the bloodstream was three times stronger for the UVB-predicted vitamin D level than for the genetically predicted one. The researchers also found that UVB radiation at a person’s residence before COVID-19 infection was strongly and inversely related to hospitalization and death. This suggests that vitamin D may protect against severe COVID-19 disease and death.
Recommendation of Vitamin D Supplementation
Although the results of the Mendelian randomization analysis were inconclusive, there was some evidence of a possible causal effect.
Because of the relatively weak association between genetically predicted vitamin D levels used for the Mendelian randomization analysis, it is possible that the number of cases in the current study was too small to convincingly determine a causal effect.
Professor Lina Zgaga, associate professor of epidemiology at Trinity College’s School of Medicine and lead author of the study, said:
“Our study provides further evidence that vitamin D may protect against severe COVID-19 infection. A properly designed randomized controlled COVID-19 trial of vitamin D supplementation is essential. Until then, given that vitamin D supplements are safe and inexpensive, it is definitely advisable to take supplements and protect oneself from vitamin D deficiency, especially when winter is around the corner.
Evropi Theodoratou, professor of cancer epidemiology and global health at the University of Edinburgh and lead researcher of the study, said:
“Given the lack of highly effective therapies against COVID-19, we believe it is important to be open-minded to the new results of rigorously conducted studies on vitamin D.”
“Covid-19 can be treated with vitamin D,” concluded a VITAL study involving 61 physicians from the Academy of Medicine in Turin.
Dr. Xue Li, study researcher from Zhejiang University, said:
“Our study supports the recommendation of vitamin D supplementation not only to maintain bone and muscle health during the blockade, but also because of the potential benefits in terms of protection against COVID-19.”
Given the strict blockade imposed by governments around the world, it is up to citizens, thinkers, researchers and scientists to question whether such methods are actually correct and uniquely useful in combating the COVID-19 outbreak.