Meta study | Vitamin D protects against the coronavirus
We have already written a few times that vitamin D protects against the coronavirus. Those posts do not do justice to the persuasiveness of the entire scientific research into this subject published so far. The meta-study published by the Italian physician Fausto Petrelli in the Journal of Steroid Biochemistry and Molecular Biology does.





Study

Petrelli and his colleagues found 43 studies on the effect of vitamin D status on coronavirus infection. A total of 621,601 subjects participated in the studies.Results
The risk of infection with the coronavirus was 26 percent higher in the group with a low vitamin D level. When the researchers looked at the subjects with a vitamin D level of less than 20 nanograms per milliliter, a low vitamin D level increased the chance of infection by as much as 50 percent.

A low vitamin D level increased the risk of serious complications during an infection by a factor of 2.6 percent. You can see this in the figure below. Click on it for a larger version.





A low vitamin D level increased the risk of death from the coronavirus by a factor of 1.22.Supplementation
The Italians found 6 studies in which researchers compared subjects with corona who took vitamin D with infected subjects who did not take vitamin D. It showed that supplementation reduced the risk of serious side effects by 73 percent.

In 7 studies, the researchers determined the effect of vitamin D supplementation on the risk of a fatal outcome of the infection. According to these studies, vitamin D supplementation reduced the risk of death by 59 percent.
Mechanism
An adequate vitamin D status has a positive effect in 2 ways during contamination with germs, Petrelli deduces from the published molecular studies. This shows that good vitamin D status "inhibits the expression of pro-inflammatory cytokines interfering with the TNF-induced NFkB1 signaling pathway, and [...] initiates the expression of interferon-stimulating genes deputed to antiviral response activating the IFN-alpha-induced YAK-STAT signaling pathway".

Simply put, an immune system that has enough vitamin D reacts more quickly and more effectively to viruses, reducing the risk of infection. If the virus does manage to infect the body, vitamin D makes that the severity of inflammation is kept within limits.
Conclusion
"Reduced vitamin D values resulted in a higher infection risk, mortality and severity COVID-19 infection", writes Petrelli. "Supplementation may be considered as preventive and therapeutic measure."

Source:
J Steroid Biochem Mol Biol. 2021 Mar 26;211:105883.