Dear Doctor: I heard on the news that if your gut isn’t in good shape, you’ll probably get a worse case of COVID-19. Is that true?
A. A study published earlier this year put forth an intriguing theory about a link between the state of someone’s gut microbiome and the severity of their COVID-19.
Research has taught us that the vast colonies of microscopic creatures living in our guts are in constant communication with the brain and have an effect on everything from mood, emotions, sleep and weight to metabolism, blood-sugar control and a range of diseases. Considering this inextricable connection, looking into a potential relationship between the trillions of microbes in our intestinal tracts and the coronavirus seems logical.
For the study, published in the journal Gut, researchers analyzed samples of blood and stool taken from 100 patients with COVID-19 whose disease was severe enough that they were admitted to the hospital and compared the results to samples drawn from 78 healthy control subjects. They found that species of certain bacteria known to play a role in the immune system were present in much lower numbers in the guts of the patients hospitalized with COVID.
They also found larger populations of certain bacteria in the patients with COVID-19, including several associated with inflammation. The researchers saw this as evidence that an imbalance in certain bacterial colonies within the gut might influence how severe illness could or would become.
They also found evidence of a potential link between these gut imbalances and the lingering symptoms known as long-haul COVID. The bacterial overgrowth included a species known as Ruminococcus gnavus, which previous studies have shown to produce a simple sugar that causes inflammation. This bacterium has been linked to Crohn’s disease and diverticulitis.
Though results of this study suggest a connection between certain gut microbiome imbalances and a more severe case of COVID-19, they do not offer conclusive proof. There’s no way to know whether the specific array of microbes in these patients’ guts existed before they became infected with the novel coronavirus or whether they arose as a result of the infection and subsequent illness.
Some are holding out hope that this line of research into the gut microbiome of COVID-19 patients might someday lead to microbe-based therapies tailored to a person’s specific gut microbiome.
Dr. Eve Glazier is an internist and associate professor of medicine at UCLA Health. Dr. Elizabeth Ko is an internist and assistant professor of medicine at UCLA Health.
