Sodium Toxicity in the Nutritional Epidemiology and Nutritional Immunology of COVID-19

Abstract

Dietary factors in the etiology of COVID-19 are understudied. High dietary sodium intake leading to sodium toxicity is associated with comorbid conditions of COVID-19 such as hypertension, kidney disease, stroke, pneumonia, obesity, diabetes, hepatic disease, cardiac arrhythmias, thrombosis, migraine, tinnitus, Bell's palsy, multiple sclerosis, systemic sclerosis, and polycystic ovary syndrome. This article synthesizes evidence from epidemiology, pathophysiology, immunology, and virology literature linking sodium toxicological mechanisms to COVID-19 and SARS-CoV-2 infection. Sodium toxicity is a modifiable disease determinant that impairs the mucociliary clearance of virion aggregates in nasal sinuses of the mucosal immune system, which may lead to SARS-CoV-2 infection and viral sepsis. In addition, sodium toxicity causes pulmonary edema associated with severe acute respiratory syndrome, as well as inflammatory immune responses and other symptoms of COVID-19 such as fever and nasal sinus congestion. Consequently, sodium toxicity potentially mediates the association of COVID-19 pathophysiology with SARS-CoV-2 infection. Sodium dietary intake also increases in the winter, when sodium losses through sweating are reduced, correlating with influenza-like illness outbreaks. Increased SARS-CoV-2 infections in lower socioeconomic classes and among people in government institutions are linked to the consumption of foods highly processed with sodium. Interventions to reduce COVID-19 morbidity and mortality through reduced-sodium diets should be explored further.

Keywords: COVID-19; SARS-CoV-2; coronavirus; mucosal immune system; nutritional epidemiology; nutritional immunology; pathophysiology; pulmonary edema; sodium toxicity; virology.

Figure 1

Pulmonary congestion following sodium chloride infusion. (a) Patient before a large infusion of sodium chloride and water in a 1969 controlled clinical trial. (b) Same patient two days after infusion, showing severe congestion from pulmonary edema due to fluid retention. Reprinted from Hutchin et al., 1969 (132). Pulmonary congestion following infusion of large fluid loads in thoracic surgery patients, The Annals of Thoracic Surgery, 8(4), 339–347, with permission from Elsevier.

Figure 2

Sodium toxicity potentially mediates the association of SARS-CoV-2 infection and COVID-19. SARS-CoV-2 is associated with COVID-19, shown in pathway C. Sodium toxicity is a common causative factor that impairs the mucociliary clearance of noninfectious virion aggregates in the nasal mucosa, causing SARS-Cov-2 infection, shown in pathway A. Sodium toxicity also causes pulmonary edema, hyperthermia, and nasal sinus edema in COVID-19, shown in pathway B. Pathway A is potentially weak or absent in post-acute COVID-19 syndrome, and pathway B is potentially weak or absent in asymptomatic infections.