Background Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) is the cause of the COVID-19 pandemic and is the cause of increased mortality, especially among elderly patients and those who have severe complications, such as chronic pulmonary obstruction, hypertension, diabetes, and cancer. Nutrition, especially micronutrients, plays an important role in reducing mortality and complications from COVID-19 because micronutrients strengthen our immune system and nutritional status is an important factor that affects the outcome of patients with COVID-19. Among micronutrients, selenium has an important effect on both intrinsic and acquired immunity. Host selenium deficiency affects the viral genome and increases the virulence of viruses. We have investigated the serum selenium levels in COVID-19 patients and healthy control individuals. Methods A total of 50 patients with COVID-19 infection were included in this study. During hospitalization, 13 patients died (non-survivor group) and 37 patients recovered (survivor group). We assessed the serum selenium levels in 50 COVID-19 patients and 50 healthy individuals by Agilent SpectrAA-240 Z atomic absorption spectrometer. Results The serum selenium level was significantly lower in COVID-19 patients (77. 8 ± 13.9 μg/L) as compared to healthy control individuals (91.7 ± 16.7 μg/L), but there was no significant difference between the survivor and non-survivor groups. Also, there was no significant relationship between serum selenium levels and laboratory findings of COVID-19 patients. Conclusions These results suggest that decreased serum selenium levels may be a risk factor for the COVID-19 infection, but there was no significant relationship between selenium and severity and mortality of COVID-19 disease.

Esophageal cancer (EC) is one of the most common types of cancer, especially in Asia. Esophageal squamous cell cancer (ESCC) is the most important histological subtype of EC, which accounts for 90% of all EC cases worldwide. ESCC is highly prevalent in Turkey, Iran, Kazakhstan and northern and central parts of China. Selenium is an essential micronutrient that is required for cellular functioning and synthesis of several selenoproteins. It also modulates the antioxidant defense system, cell cycle and apoptosis. This article reviews the most important molecular mechanisms of EC and investigates the association between selenium level and incidence of EC in high-risk areas.

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