Nutritional status, diet and viral respiratory infections: perspectives for severe acute respiratory syndrome coronavirus 2

Abstract

COVID-19, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), was recognised by the WHO as a pandemic in 2020. Host preparation to combat the virus is an important strategy to avoid COVID-19 severity. Thus, the relationship between eating habits, nutritional status and their effects on the immune response and further implications in viral respiratory infections is an important topic discussed in this review. Malnutrition causes the most diverse alterations in the immune system, suppressing of the immune response and increasing the susceptibility to infections such as SARS-CoV-2. On the other hand, obesity induces low-grade chronic inflammation caused by excess adiposity, which increases angiotensin-converting enzyme 2. It decreases the immune response favouring SARS-CoV-2 virulence and promoting respiratory distress syndrome. The present review highlights the importance of food choices considering their inflammatory effects, consequently increasing the viral susceptibility observed in malnutrition and obesity. Healthy eating habits, micronutrients, bioactive compounds and probiotics are strategies for COVID-19 prevention. Therefore, a diversified and balanced diet can contribute to the improvement of the immune response to viral infections such as COVID-19.

Keywords: COVID-19; Inflammation; Malnutrition; Obesity; Ultra-processed foods.

Fig. 1.

Relationship between malnutrition, dietary imbalance, obesity and impaired immune response, leading to greater susceptibility to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Nutritional status is related to inflammation so that both malnutrition and obesity alter the innate and adaptive immune responses, increasing the risk of infections by various pathogens^(–,,–33). There is a synergic vicious cycle where infections induce a response that produces fever, increased catabolism, loss of appetite and altered intestinal absorption. These changes increase nutritional demands and, in addition to the loss of appetite, induce or aggravate malnutrition^(41,43). Otherwise, pro-inflammatory cytokines (TNF-α, IL-6 and IL-8) that act to fight pathogens are produced to a lesser extent in malnutrition, while anti-inflammatory cytokines, such as IL-10 increase⁽⁴⁷⁾. The post-infection prognosis of obese individuals is worse^(53,55) because there are higher expressions and productions of angiotensinogen, angiotensin-converting enzyme 2 (ACE2), leptin and pro-inflammatory cytokines: TNF-α, IL-6 and IL-1β^(18,52,53). The dietary imbalance caused by the consumption of refined sugars, hydrogenated fats, poorly digested allergenic proteins, processed and ultra-processed foods increase the inflammatory index of the diet and has been associated with respiratory infection of the airways^(,,–77). Besides, this dietary pattern provides a small content of vitamins (especially vitamins A, C, D and E) and minerals (iron, zinc and selenium), which can be deficient in situations of malnutrition and obesity^(16,69). These vitamins and minerals are also essential for immunocompetence against infections.