Bicarbonate: An Ancient Concept to Defeat Pathogens in Light of Recent Findings Beneficial for COVID-19 Patients?

A century ago during the Spanish influenza pandemic bicarbonate was suggested to be effective in pathogen defense. Nevertheless, modern physiology has focused on its role as the principal buffer of extracellular fluid. Recently, scientific data have accumulated pointing to critical roles of bicarbonate in calcium chelation and antimicrobial defense. In view of the worldwide attention focused on the COVID-19 pandemic, we analyze possible roles of bicarbonate in viral infections. Since SARS-CoV entry is heavily dependent on extracellular Ca2+, bicarbonate may hamper the viral replication. Respiratory viruses could inhibit epithelial bicarbonate secretion, which decreases the airway pH. Administration of bicarbonate increases the pH thus, enhances the activity of antimicrobial peptides. Bicarbonate potentiates neutrophil extracellular trap formation and regulates macrophage polarization modulating inflammatory responses. Most importantly, inhalation of nebulized NaHCO3 has been reported to be safe in various pulmonary diseases. Thus, we propose bicarbonate as a simple management option for COVID-19 patients.