COVID-19 is a pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Early reported symptoms include fever, cough, and respiratory symptoms. There were few reports of digestive symptoms. However, with COVID-19 spreading worldwide, symptoms such as vomiting, diarrhoea, and abdominal pain have gained increasing attention. Research has found that angiotensin-converting enzyme 2 (ACE2), the SARS-CoV-2 receptor, is strongly expressed in the gastrointestinal tract and liver. Whether theoretically or clinically, many studies have suggested a close connection between COVID-19 and the digestive system. In this review, we summarize the digestive symptoms reported in existing research, discuss the impact of SARS-CoV-2 on the gastrointestinal tract and liver, and determine the possible mechanisms and aetiology, such as cytokine storm. In-depth exploration of the relationship between COVID-19 and the digestive system is urgently needed.
COVID-19/complications , Gastrointestinal Diseases/etiology , Liver Diseases/etiology , Pandemics , SARS-CoV-2/pathogenicity , Angiotensin-Converting Enzyme 2/metabolism , Anorexia/etiology , Antiviral Agents/adverse effects , Bile Ducts/metabolism , Bile Ducts/virology , COVID-19/epidemiology , COVID-19/immunology , COVID-19/pathology , Chemical and Drug Induced Liver Injury/etiology , Comorbidity , Cytokine Release Syndrome/etiology , Cytopathogenic Effect, Viral , Gastrointestinal Diseases/epidemiology , Gastrointestinal Microbiome , Gastrointestinal Tract/metabolism , Gastrointestinal Tract/pathology , Gastrointestinal Tract/virology , Humans , Immunosuppressive Agents/adverse effects , Liver/metabolism , Liver/pathology , Liver/virology , Liver Diseases/epidemiology , Liver Transplantation , Non-alcoholic Fatty Liver Disease/etiology , Non-alcoholic Fatty Liver Disease/pathology , Non-alcoholic Fatty Liver Disease/virology , Postoperative Complications , Receptors, Virus/metabolism
