Vitamin D: Immune system and respiratory infections, we’re going to talk about how Vitamin D regulates the immune system and particularly we’re going to talk about how it regulates the immune system against respiratory infections, so what is Vitamin D, there are actually multiple forms of Vitamin D, Vitamin D is a fat-soluble vitamin involved in calcium homeostasis but it is also known to have roles in immune system modulation, Vitamin D plays a role in modulating the immune system there has been questioned, as to does it play a role, and what role does it play in SARS or Covid-19 infections, Vitamin D has been associated with increased susceptibility to infections like acute respiratory tract infections and Vitamin D has been shown to decrease risk of respiratory infections and or severity of respiratory infections,
Vitamin D actually reduces morbidity associated with tuberculosis another infection that’s associated with Vitamin D deficiency is influenza and another one is bacterial vaginitis, there are other infections but these are a few that I wanted to mention here, Vitamin D supplementation to prevent acute respiratory tract infections systematic review and meta-analysis of individual participant data which was published in BMJ in 2017, meta-analysis which means that the authors of this meta-analysis have that many different other articles and conglomerated the evidence and data into this article so what this meta-analysis has shown is that Vitamin D supplementation is associated with the reduction in acute respiratory tract infections, some of these studies actually show an increase in respiratory tract infections with Vitamin D supplementation but for the most part most of them show a negative or a decrease in respiratory tract infections with Vitamin D supplementation, looking at the combined adjusted odds ratio we see that the combined adjusted odds ratio for all of these studies comes to showing that Vitamin D supplementation reduces the incidence of respiratory tract infections and this data is statistically significant, additionally because of the variation in the data from these articles the authors of the meta-analysis also did a subgroup analysis so subgroup analysis is essentially where the authors looked more specifically at certain groups of participants,
What they found was that Vitamin D supplementation has the strongest protective effect in groups with Vitamin D deficiency so groups where their baseline Vitamin D levels were less than 25 Nano moles per liter the authors of this meta-analysis also looked at how dosing plays a role in Vitamin D supplementation and acute respiratory tract infections, what was that dosing is also an important factor daily or weekly dosing of Vitamin D was found to be protective but colas dosing did not show protective effects so what is bolus dosing, bolus dosing is where an individual takes a very large amount of Vitamin D all at once and doesn’t take consistently over time so they only take big large amounts once in a while so dosing in the context of this article was described as 30,000 units of Vitamin D,
So very large dose of Vitamin D so what this means is that taking a layer weekly dosing of Vitamin D consistently over long periods of time at appropriate doses so doses that are recommended are better at reducing the risk of respiratory infections, so if you haven’t taken any dose of Vitamin D and your take a very large dose it doesn’t actually show any protective effects, it’s important to do it over a consistent period of time with appropriate doses so now having said all that how does Vitamin D actually protect against respiratory tract infections, so Vitamin D is involved in immune system regulation as we mentioned before and Vitamin D receptors are actually present in many immunological cells, these include B cells and T cells macrophages and dendritic cells, and by way of activating their Vitamin D receptors Vitamin D can modulate innate and adaptive immune system function, and it does this by up regulating immune system proteins like catholicity pens and defensing these antimicrobial proteins have antibacterial antiviral and antifungal properties.
I’m only going to talk briefly about Vitamin D, supplementation can modulate levels of interleukins like interleukin 6 it can actually decrease interleukin 6 so this is another mechanism by which Vitamin D may have a possible role in reducing the morbidity and mortality of Covid-19, now that we know that background information, Vitamin D levels are inversely correlated with many of these factors so what I mentioned here was talked about in this article entitled evidence, that Vitamin D supplementation could reduce risk of influenza and Covid-19 infections, which was published in the journal nutrients in 2020 and here is a table from that article