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.

Zinc is an essential micronutrient for growth and development. Its deficiency causes growth retardation in children and adolescents. The present study analyzes the effect of zinc on growth hormone (GH) secretion, insulin-like growth factor 1 (IGF1), and insulin-like growth factor-binding protein 3 (IGFBP3) in normal children before puberty. Thirty normal children were studied, 15 boys and 15 girls, aged 6-9 years. They were orally supplemented with 5 mg Zn/day for 3 months and 0.06537 mg Zn/kg body weight was injected before and after oral supplementation. Dietary intake and anthropometric measurements were assessed at baseline and end of study. Plasma GH levels increased during intravenous zinc administration and IGF1 and IGFBP3 increased after oral zinc supplementation. There was a positive correlation between the areas under the curves of GH and zinc after oral supplementation. Zinc supplementation was possibly effective in improving the body zinc status of the children, secretory levels of IGF1 and IGFBP3, GH potentialization, and height.

The parameters derived from bioelectrical impedance, phase angle (PA) and bioelectrical impedance vector analysis (BIVA) have been associated with cell membrane integrity and body cell mass. Zinc is a micronutrient that exerts important structural functions and acts in maintaining cellular functionality. To evaluate cell integrity and body cell mass, PA and BIVA were evaluated in children orally supplemented with zinc at different concentrations. Anthropometric, bioelectrical (resistance and reactance) and serum zinc variables were collected from two randomized, triple-blind, controlled clinical trials. Sampling was composed of 71 children consisting of three groups: a control group who received a placebo and two experimental groups who received oral supplementation of 5 or 10 mg-Zn/day for three months. The three groups presented increases (p < 0.001) in the linear height and weight. In the group supplemented with 10 mg-Zn/day, there was an increase in reactance values (p = 0.036) and PA (p = 0.002), in addition to vector displacement (p < 0.001) in relation to the confidence ellipses. An increase in serum zinc concentration was found (p < 0.001) in all three groups. Whit this, the supplementation with 10 mg-Zn/day promotes changes in the integrity of the cell membrane associated with the increase in the cellular mass of healthy children.

Assessing severity and nutritional prognosis in critical patients has become increasingly important in recent years, since these parameters are related to morbidity/mortality and used to guide therapeutic options. Determine nutritional prognosis through the Phase Angle (PA) and Onodera's Prognostic Nutritional Index (OPNI) and its relationship with severity, hospitalization time and mortality of critically ill patients. Descriptive cross-sectional study, involving adult patients hospitalized in an Intensive Care Unit (ICU). Data were collected from the patients' medical records to calculate severity indicators (APACHE II, SOFA and SAPS 3) and determine the length of hospitalization and outcome. Bioimpedance was conducted to calculate the PA, using resistance and reactance data. A total of 35 patients (26% men and 74% women), with mean age of 55.5 ± 16.7 years, were included. The mortality rate (17%) was similar to that expected by APACHE II and SOFA, but higher than that predicted by SAPS 3. The mean values for the PA (4.2 ± 1.0) and OPNI (38.7 ± 8.3) were lower than the reference values adopted. Individuals with PA < 5.1 exhibited significantly lower reactance and albumin and higher APACHE II and SOFA values, in addition to longer hospitalization time and higher mortality. The PA was inversely correlated with all the severity indicators under study (APACHE II, SOFA and SAPS 3), and the length of hospitalization. By contrast, there was no correlation between OPNI and these parameters, or between PA and OPNI. The PA proved to be a good tool in assessing nutritional prognosis in critically ill patients. By contrast, more studies using the OPNI with this type of patients are needed.