Metabolic diseases are associated with a higher risk of a severer coronavirus disease 2019 (COVID-19) course, since fatty liver is commonly associated with metabolic disorders, fatty liver itself is considered as a major contributor to low-grade inflammation in obesity and diabetes. Recently a comprehensive term, metabolic (dysfunction) associated fatty liver disease (MAFLD), has been proposed. The hepatic inflammatory status observed in MAFLD patients is amplified in presence of severe acute respiratory syndrome coronavirus 2 infection. Intestinal dysbiosis is a powerful activator of inflammatory mediator production of liver macrophages. The intestinal microbiome plays a key role in MAFLD progression, which results in non-alcoholic steatohepatitis and liver fibrosis. Therefore, patients with metabolic disorders and COVID-19 can have a worse outcome of COVID-19. This literature review attempts to disentangle the mechanistic link of MAFLD from COVID-19 complexity and to improve knowledge on its pathophysiology.

The coronavirus disease 2019 (COVID-19) pandemic may present with a broad range of clinical manifestations, from no or mild symptoms to severe disease. Patients with specific pre-existing comorbidities, such as obesity and type 2 diabetes, are at high risk of coming out with a critical form of COVID-19. Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease, and, because of its frequent association with metabolic alterations including obesity and type 2 diabetes, it has recently been re-named as metabolic-associated fatty liver disease (MAFLD). Several studies and systematic reviews pointed out the increased risk of severe COVID-19 in NAFLD/MAFLD patients. Even though dedicated mechanistic studies are missing, this higher probability may be justified by systemic low-grade chronic inflammation associated with immune dysregulation in NAFLD/MAFLD, which could trigger cytokine storm and hypercoagulable state after severe acute respiratory syndrome coronavirus 2 infection. This review focuses on the predisposing role of NAFLD/MAFLD in favoring severe COVID-19, discussing the available information on specific risk factors, clinical features, outcomes, and pathogenetic mechanisms.

The incidence of liver injury after coronavirus disease 2019 (COVID-19) infection ranged from 15%-53%. The mechanism includes direct viral cytopathic effect, cytokinesis, and treatment drug-induced liver injury. The symptoms include nausea, vomiting, diarrhea, and loss of appetite. The laboratory results include increased liver enzyme levels, decreased monocyte count, and longer prothrombin time. The most common imaging findings are hepatomegaly on ultrasound, ground-glass opacity on chest computed tomography (CT), and liver hypodensity and pericholecystic fat stranding on abdominal CT. Patients may also have different presentations and poor outcomes of different liver diseases concomitant with COVID-19 infection. Liver function test (LFT) results should be monitored, and all factors known to cause or predispose liver injury should be investigated while managing the patients. The risks of transfer to an intensive care unit, need for mechanical ventilator support, and acute kidney injury is higher in COVID-19 patients with than without abnormal LFTs. Increased mortality and length of hospital stay are both observed.

The incidence of liver injury after coronavirus disease 2019 (COVID-19) infection ranged from 15%-53%. The mechanism includes direct viral cytopathic effect, cytokinesis, and treatment drug-induced liver injury. The symptoms include nausea, vomiting, diarrhea, and loss of appetite. The laboratory results include increased liver enzyme levels, decreased monocyte count, and longer prothrombin time. The most common imaging findings are hepatomegaly on ultrasound, ground-glass opacity on chest computed tomography (CT), and liver hypodensity and pericholecystic fat stranding on abdominal CT. Patients may also have different presentations and poor outcomes of different liver diseases concomitant with COVID-19 infection. Liver function test (LFT) results should be monitored, and all factors known to cause or predispose liver injury should be investigated while managing the patients. The risks of transfer to an intensive care unit, need for mechanical ventilator support, and acute kidney injury is higher in COVID-19 patients with than without abnormal LFTs. Increased mortality and length of hospital stay are both observed.

There has been a deluge of scientific data since coronavirus disease 2019 (COVID-19) was first reported. The effects of COVID-19 on the digestive system are now increasingly well understood. This article aims to review the current data on the effects of COVID-19 on the digestive system with particular emphasis on preexisting digestive diseases and its implications on nutrition practices.

Evidence has shown that Severe acute respiratory syndrome coronavirus 2 virus affects the gastrointestinal (GI) tract, pancreas and hepatobiliary system resulting in different GI manifestations. Several preexisting digestive diseases have been investigated. These studies have revealed that these special patient population groups are generally not at an increased risk to contract COVID-19, but are susceptible to develop increasing severity of disease. Aside from medical therapy, optimizing nutritional care has a beneficial role in this group of patients.

GI manifestations of COVID-19 in addition to preexisting digestive diseases have an impact on patient's nutrition. Digestion, absorption and transport of nutrients may be impaired. To date, there are no existing guidelines on the nutritional management of patients for this particular at-risk group. Most nutrition practices are based only on observations and clinical experience. Basic prepandemic nutrition care principles are primarily followed but often individualized based on clinical judgment.

Based on recent evidence on the importance of the presence of diabetes mellitus (DM) and fibrosis-4 (FIB-4) index in coronavirus disease 2019 (COVID-19) mortality, we analyzed whether these factors could additively predict such mortality.

This multicenter observational study included 1,019 adult inpatients admitted to university hospitals in Daegu. The demographic and laboratory findings, mortality, prevalence of severe disease, and duration of quarantine were compared between patients with and without DM and/or a high FIB-4 index. The mortality risk and corresponding hazard ratio (HR) were analyzed using the Kaplan-Meier method and Cox proportional hazard models.

The patients with DM (n=217) exhibited significantly higher FIB-4 index and mortality compared to those without DM. Although DM (HR, 2.66; 95% confidence interval [CI], 1.63 to 4.33) and a high FIB-4 index (HR, 4.20; 95% CI, 2.21 to 7.99) were separately identified as risk factors for COVID-19 mortality, the patients with both DM and high FIB-4 index had a significantly higher mortality (HR, 9.54; 95% CI, 4.11 to 22.15). Higher FIB-4 indices were associated with higher mortality regardless of DM. A high FIB-4 index with DM was more significantly associated with a severe clinical course with mortality (odds ratio, 11.24; 95% CI, 5.90 to 21.41) than a low FIB-4 index without DM, followed by a high FIB-4 index alone and DM alone. The duration of quarantine and hospital stay also tended to be longer in those with both DM and high FIB-4 index.

Both DM and high FIB-4 index are independent and additive risk factors for COVID-19 mortality.