Study finds no link between vitamin D and COVID-19 outcomes

New research shows a lack of an association between Vitamin D deficiency and the number of coronavirus disease 2019 (COVID-19) cases, recoveries, or mortality rates in European countries.

Malnutrition can increase a person’s risk of mortality from various diseases. Previous studies have examined if vitamin D deficiency could influence the prevalence of COVID-19, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Some postulate that vitamin D can protect against lung infection by attenuating an overactive immune system and preventing acute respiratory syndrome (ARS), both of which are associated with severe and critical COVID-19.

However, Dimitra Rafailia Bakaloudi and Michail Chourdakis from the Aristotle University of Thessaloniki in Greece argue there’s no clinical evidence to corroborate these claims.

The team writes:

In the light of the most recent evidence of the COVID-19 pandemic, as well as by using updated Vit D deficiency prevalence for each included country, we can end up in more accurate conclusions.”

The study “Prevalence of vitamin D is not associated with the COVID-19 epidemic in Europe. A judicial update of the existing evidence” is available as a preprint on the medRxiv* server, while the article undergoes peer review.

Collecting data

The researchers compiled data on COVID-19 infections, recoveries, and mortality rates using the Worldometer website. They gathered information on the prevalence of Vitamin D deficiency in 24 European countries through the PubMed database, with the last data point being February 6, 2021.

They evaluated vitamin D deficiency by its prevalence instead of mean Vitamin D levels.

Study population size on Vitamin D deficiency varied by country, with Slovenia being the lowest at 280 and Italy being the highest at 74,235.

Vitamin D deficiency differed across Europe

Finland had the lowest Vitamin D deficiency at 6%, whereas Turkey reported the highest Vitamin D deficiency at 75.5%.

About 11 of the 24 countries had their adult populations more than 50% deficient in Vitamin D.

When evaluating larger countries, the researchers looked at the total number of COVID-19 cases per 1 million of the total population. Based on this measurement, Russia had the lowest amount at 2.684 per 1 million in the population infected with SARS-CoV-2. The Czech Republic had the highest coronavirus infections when looking at the total population. They reported 94,522 per 1 million.

Norway experienced the lowest COVID-19 mortality rate with 105 deaths for every 1 million. The highest COVID-19 mortality rate was in Belgium, with 1,826 deaths.

In terms of recovery, Switzerland had the lowest number of COVID-19 libraries, and the Czech Public had the highest number of recoveries.

There was no significant association between Vitamin D and COVID-19 cases and mortality.

“Although only 24 European countries satisfied our inclusion criteria, the analysis included a significant part of the European population. Therefore, the results of our study could be generalized to most of the excluded European countries too. Moreover, along with most high-income countries, upper-middle income countries, such as Russia and Bosnia and Herzegovina, were also included in the analysis, reflecting the effect of economic status in the outcomes.”

The researchers only evaluated Vitamin D deficiency data and not from a national level survey, which could have been more representative of countries current population.

A “mean” value cannot represent the Vit D status of a whole country because outliers and skewed populations influence it. However, we have also conducted these analyses using updated data regarding Vit D mean concentration (only from the last decade) without finding any statistical significance,” wrote the team.

Based on the findings, the researchers suggest the government should create more preventative measures to increase awareness of the risk of Vitamin D deficiency in high-risk groups. They should also increase information on the lack of significant association between Vitamin D and the coronavirus pandemic outcomes.

*Important Notice

medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.

Written by

Jocelyn Solis-Moreira

Jocelyn Solis-Moreira graduated with a Bachelor's in Integrative Neuroscience, where she then pursued graduate research looking at the long-term effects of adolescent binge drinking on the brain's neurochemistry in adulthood.