Inclusion Criteria:  Diagnosis of covid-19 diseased patients admitted to the ICU with enteral nutrition.  Exclusion Criteria:  Renal failure (creatinine >180 mmol/l) Hepatic failure (bilirubin >40 mmol/l, alanine aminotransferase >100 U/l and aspartate aminotransferase >100 U/l) Severe neutropenia (<500 cells/mm3) Patients receiving cytotoxic, radiation and/or steroid therapy Hemodynamic instability