Poor gut health may increase the severity of COVID-19, which is often accompanied by gastrointestinal symptoms like diarrhea. According to the American Society for Microbiology, a growing collection of evidence shows that having an altered gut microbiome allows the virus to gain entry into the GI tract.
Dr. Heenam Stanley Kim, an expert at the Korea University Laboratory for Human-Microbial Interactions, reports that gut dysfunction may exacerbate the severity of infection by enabling the virus to access the surface of the digestive tract and internal organs.
COVID-19 patients experience a wide range of symptoms, the most common of which are high fevers and respiratory problems. Autopsies have confirmed that COVID-19 infection can also affect the liver, kidney, heart, spleen, and the gastrointestinal tract. These organs are vulnerable to infection because they have a number of ACE2 receptors that are targeted by the SARS-CoV-2 spike protein.
A substantial amount of hospitalized patients with breathing problems also have diarrhea, nausea, and vomiting. This indicates that when the virus breaches the GI tract, it worsens the severity of the disease. “There seems to be a clear connection between the altered gut microbiome and severe COVID-19,” explained Dr. Kim.
Older adults and people with underlying medical conditions including high blood pressure, diabetes, and obesity are known to face a higher risk of severe COVID-19. Both of these factors – age and chronic conditions – are also associated with an altered gut microbiome.
Dr. Kim noted that this imbalance can affect gut barrier integrity, which can give pathogens easier access to cells in the intestinal lining. He is not the only expert who has promised the idea that unhealthy gut microbiomes may be an underlying reason for why some people have such severe infections.
In Singapore, a study on symptomatic COVID-19 patients found that about half had a detectable level of the coronavirus in fecal tests, but only about half of those experienced GI symptoms. Dr. Kim pointed out that a person’s gut health at the time of infection may be critical for symptom development.
The disease has been linked to a decrease in beneficial gut bacterial species, as well as an increase in pathogenic bacteria. Furthermore, many recent studies have found reduced bacterial diversity in gut samples collected from COVID-19 patients compared to samples from healthy people.
The researchers have identified bacterial species which may provide resistance to COVID-19 infection, including some families that are responsible for producing butyrate, a short-chain fatty acid. This bacteria plays a critical role in gut health by reinforcing gut-barrier function.
Dr. Kim said he started analyzing studies on the link between COVID-19 severity and gut health after realizing that wealthy countries with a good medical infrastructure, including the United States and nations in Western Europe, were among the hardest hit by the virus. The most common diets in these countries are low in fiber.
“A fiber-deficient diet is one of the main causes of altered gut microbiomes, and such gut microbiome dysbiosis leads to chronic diseases,” explained Dr. Kim.
Eating more fiber, he said, may lower a person’s risk of serious disease. And fecal microbiota transplantation might be a treatment worth considering for patients with the worst cases of COVID-19.
According to Dr. Kim, the problem with poor gut health goes beyond COVID-19. “The whole world is suffering from this COVID-19 pandemic, but what people do not realize is that the pandemic of damaged gut microbiomes is far more serious now.”
The study is published in the journal mBio.