With huge interest in the potential of vitamin D to protect against COVID-19, data from 24 European countries suggest no association between vitamin D status and COVID-19.
The potential protective role of vitamin D in either preventing or reducing the risk of infection with COVID-19 has attracted much attention during the pandemic. In an assessment of the available evidence by NICE in the UK, it was recommended not to provide vitamin D to either prevent or treat COVID-19 except as part of a clinical trial. Furthermore, in an analysis of the correlation between vitamin D levels and COVID-19 cases in 20 European countries, although a significant negative correlation was observed, the study also reported a non-significant correlation between vitamin D levels and death from COVID-19. In an attempt to further explore this relationship, a team from the School of Medicine, Faculty of Health Sciences, Aristotle University, Greece, looked at the problem from a different angle. The team collated statistics on COVID-19 infections, recoveries and mortalities from the worldometer website and data on vitamin D levels from a comprehensive review of the literature. However, rather than calculating a “mean” vitamin D level for each country, which was the approached taken in previous studies, the team used the prevalence of vitamin D deficiency for each country, based on data from the last decade. This information was derived from a comprehensive search of the literature, including only studies that were population-based, in adults and where vitamin D deficiency was reported as a serum concentration < 20ng/ml. The final analysis involved exploring the relationship between the prevalence of vitamin D deficiency and variables such as the number of COVID-19 infections, recoveries and mortalities per 1 million population.
The results suggested that vitamin D deficiency was common throughout the 24 European countries studied. It ranged from 6% (Finland) to 75.5% (Turkey) and in 11 of the countries the data suggested that more than 50% of the population were vitamin D deficient. Cases of COVID-19 were found to be positively correlated with the prevalence of vitamin D deficiency although this was non-significant (Pearson’s correlation, r = 0.19, p = 0.374). Similarly, there was a non-significant correlation between vitamin D deficiency and recovery from COVID-19 (r = 0.31, p = 0.131) and death (r = 0.129, p = 0.549) per one million population. In discussing their findings the authors noted that their analysis shows that there was no apparent relationship between vitamin D deficiency among the European populations studied and COVID-19 infection, recovery or mortality.
They concluded that vitamin D deficiency is not a strong risk factor for any of the outcomes associated with COVID-19.
Bakaloudi D, Chourdakis M. Prevalence of vitamin D is not associated with the COVID-19 epidemic in Europe. A judicial update of the existing evidence. MedRxiv 2021 doi: https://doi.org/10.1101/2021.03.04.21252885