OBJECTIVE: Considering the rapid spread of COVID-19, the scientific community has been looking for ways to recognize factors that may interfere with the outcome of viral infection. Despite the lack of studies with the new coronavirus, it is known that adequate serum levels of micronutrients are essential for the organic response to infectious diseases. Thus, we aim to review the effects of vitamin A, D, iron, zinc, or folate deficiency on the prognosis of patients with respiratory infections with manifestations similar to COVID-19 and discuss about supplementation of the nutrients analyzed in this review. METHODS: The search was conducted in the databases PubMed, Lilacs, and SciELO, including observational studies published between 2010-2020, with results for individuals with respiratory tract infections with manifestations similar to COVID-19. RESULTS: Six articles met the inclusion criteria, all of which were related to deficiencies of vitamins A and D. In general, vitamin A deficiency was associated with cough, fever, and greater total respiratory resistance. Regarding vitamin D, the lack of this nutrient led to higher rates of ICU admission, the need for mechanical ventilation, and mortality. Evidence linking specific relationships between nutritional deficiencies and COVID-19 remain lacking due to the small number of studies and heterogeneities in population subgroups. CONCLUSION: In conclusion, deficiencies of vitamins A and D seem to negatively affect the prognosis of respiratory tract infections. Supplementation of these nutrients for prevention or treatment of patients diagnosed with COVID-19 should respect serum levels, nutritional status and housing conditions (e.g.,endemic location) of individuals.
To review scientific evidence on the effects of a gluten-free diet on body composition and improvement of clinical and biochemical parameters of metabolic syndrome. The Preferred Reporting Items for Systematic Reviews and Meta-Analyzes -PRISMA guidelines were followed. A literature search was performed in the PubMed, ScienceDirect, Trip Database, Bireme and Scielo databases, without language restriction, until March 2021. The terms "gluten-free diet", "obesity", "metabolic syndrome", and "weight loss", and Boolean operators (AND/OR) were used. The clinical hypothesis was structured according to the acronym PICOT. Randomized clinical trials with adult and elderly humans without a diagnosis of celiac disease, consuming a gluten-free diet, evaluating associations of the effects of this diet on weight loss and metabolic syndrome components were considered eligible. To assess the risk of bias, the RoB2 was used. A total of 3,198 articles were identified and, after the screening and evaluation of pre-defined eligibility criteria, four studies were included in the qualitative analysis. Weight loss was not associated with a gluten-free diet. However, individuals under a gluten-free diet had lower mean waist circumference, fat percentage (-2.3%) and serum triglyceride levels. The impact of a gluten-free diet on metabolic syndrome parameters is still controversial. In individuals without gluten sensitivity or celiac disease, the consumption of a gluten-free diet appears to provide no nutritional benefit.
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