Hello, readers! I am trying to make good on a recurring promise I make in this blog, to provide more papers on how gut bacteria affect the human immune system (and so by doing, affect many of the maladies that humans suffer from). Today I’m focusing on COVID-19 and two papers describing how dysbiosis (or a non-optimal assortment of organisms) can impact progression of symptoms. One is a hypothesis paper, and the other study is an actual investigation of samples from patients.
The first article was first published online in May 2020: Gut microbiota and COVID-19- possible link and implications. This is basically an hypothesis paper, and it outlines the case for the assortment of bacteria in your gut to affect pathologies occurring in the rest of your body. It mentions the gut-lung axis, how influences which affect gut microbiota composition will also affect immune system functioning (diet, exercise, stress) and suggests use of probiotics or prebiotics (food which helps promote the growth of probiotics) in preventing COVID-19 symptoms. I’ve suggested something along these lines myself, although I specifically suggest lactic acid bacteria and dairy products (see my last post).
The second article was published just last month, in September 2020, and is an investigation of the actual composition of the gut microbiome versus susceptibility to COVID-19. As suspected, there is a link: they found increases in bacteria which seem to promote inflammation and decreases in ones that had the opposite effects, when patients sick from COVID-19 were contrasted with healthy controls. This was a study on a limited number of patients (6 severely ill versus 15 healthy controls) but it is intriguing.
It’s not surprising that there is a link between dysbiosis and probability of contracting serious symptoms upon viral infection, since (a) the worst symptoms of COVID-19 have to do with runaway inflammatory reactions that over-stimulate your immune system (a cytokine storm) and we already know that many bacteria influence the human immune system, and (b) it’s already known that people who are older or have more pre-existing conditions (both states in which the gut microbiome is more likely to be dysbiotic) are also more likely to suffer severe symptoms when infected.
A treatment which is nonliving and yet can mimic the effects of a healthy microbiome containing many immune system modulating probiotics (I say “modulating” because you want your immune system to be at a healthy state somewhere between over-exertion and under-exertion) would be ideal, and I have some ideas about that but they obviously require development. If I had collaborators this would be possible, but I can’t really see a point at which this will happen.