Severe Course of COVID-19 May Be Associated With Poor GI Health

Significant numbers of patients hospitalized with severe cases of COVID-19 also experience gastrointestinal (GI) symptoms, including diarrhea and vomiting, which suggests an association between GI involvement and severity of COVID-19, according to a new review.  

In the journal of the American Society for Microbiology (ASM), mBio, microbiologist Heenam Stanley Kim, PhD, from the Laboratory for Human-Microbial Interactions at Korea University in Seoul, noted that high-income nations with advanced medical infrastructures were among those most severely affected by the COVID-19 pandemic. He hypothesized that poor outcomes could be associated with the so-called “Western diet” popular in wealthier countries, which lacks sufficient dietary fiber and has been implicated in creating gut dysbiosis.

Both older age and chronic illnesses—risk factors for more severe cases of COVID-19—are known to also be associated with altered intestinal microbiota. Researchers have observed that samples of intestinal microbiota obtained from patients with COVID-19 showed reductions in bacterial diversity when compared with samples from healthy controls. These samples also exhibited greater numbers of pathogens as well as reductions in beneficial bacteria. Another study reported that patients whose samples showed abundant beneficial gut bacteria were less likely to develop severe COVID-19.  

Dr Kim proposed that altered microbiomes and “leaky gut” might enable the SAR-CoV-2 virus to infiltrate the gastrointestinal system and other organs where the protein angiotensin-converting enzyme 2 is populous on the surface, and then to enter the bloodstream. However, the author stated, the presence of SARS-CoV-2 in the GI system does not consistently lead to vomiting, diarrhea, and other gastric symptoms. In a study conducted in Singapore, half of the patients with COVID-19 who were examined showed detectable virus in fecal samples, but only half of those patients presented with any GI symptoms.

Should additional studies support the hypothesis that gut health affects COVID-19 prognosis, the association could provide direction for efforts to prevent and treat COVID-19. However, Dr Kim stated in a news release from ASM, gut health remains a major global health issue that should be addressed.

"The whole world is suffering from this COVID-19 pandemic," Dr Kim said, "but what people do not realize is that the pandemic of damaged gut microbiomes is far more serious now."


—Rebecca Mashaw



  1. Kim HS. Do an altered gut microbiota and an associated leaky gut affect COVID-19 severity? mBio. 2021;12(1). doi:10.1128/mBio.03022-20
  2. Poor gut health connected to severe COVID-19, new review shows. News release. Washington, DC. American Society for Microbiology. January 12, 2021. Accessed January 13, 2021.,-New.