Sobrepeso, obesidade e associações com o status de vitamina A: uma revisão narrativa

Abstract

Obesity is characterized by an excess of body fat, defined an amount capable of causing damage to the individual's health. It is a chronic, progressive disease involving multifactorial causes linked especially to lifestyle and genetic, hereditary, psychological, cultural and ethnic factors. The changes that have taken place in recent decades regarding to dietary patterns have contributed to nutritional deficiencies, which tend to impair important functions in the body. Studies show that vitamin and mineral deficiencies tend to be common in people with obesity, as in the case of vitamin A, which can be influenced by both low consumption and excess weight, as it is a fat-soluble vitamin and can accumulate in adipose tissue. It is therefore important to investigate the associations between the development of obesity and its implications for serum vitamin A concentrations in obese people. The aim of this study was to understand and explain the possible relationships between overweight and obesity and vitamin A. It was guided by the following question: “Are overweight and obesity capable of triggering changes in serum vitamin A concentrations?”. A narrative review was carried out using the PubMed, Web of Science, ScienceDirect, Embase and Scopus search engines in order to evaluate content linked to the aim of this study. This review included clinical studies carried out on humans from 2014 to 2024. After the searches, 9 articles were selected, which involved research on children and adolescents (n=4), women only (n=3) and adult men and women (n=2). In children and adolescents, the results varied between studies that did not indicate a relationship between vitamin A and excess weight and others that showed significantly higher concentrations in the overweight or obese group; reduced serum concentrations of retinol and of β-carotene in girls and boys with obesity, respectively. The studies involving women indicated higher percentages of serum vitamin A inadequacy in the overweight and obese groups; a higher prevalence of inadequate serum retinol concentration, worsening vitamin A deficiency and low serum β-carotene concentrations in those with body adiposity measurements above the cut-off points, as well as a significant decrease in serum retinol and β-carotene concentrations as BMI increased and lower dietary intake of vitamin A in the overweight and obese group. In the adult population, one study indicated that BMI was inversely associated with serum retinol concentrations and another study reported that vitamin A concentrations were significantly lower in the obese group. It can be concluded that the associations between overweight and obesity and vitamin A are not yet conclusive, and further clinical studies in humans are needed to confirm and discuss the possible causes between the variables studied