Role of vitamin D in insulin resistance in obese individuals

BACKGROUND: Vitamin D is a fat-soluble compound responsible for promoting intestinal absorption of calcium, and this, in turn, acts as a signal transmitter or activator as protein in secretory processes and release of hormones. VitaminD receptors are distributed in various tissues of the body and involved in biochemical reactions in the pathogenesis of several diseases, such as obesity. OBJECTIVE: The aim of this article is to provide updated information on the role of vitamin D in insulin resistance inobese individuals. METHODS: It was conducted a search of articles published in PubMED, SciELO, and LILACS database, without limit forthe year of publication, using the keywords"vitamin D","insulin resistance",and "obesity". RESULTS: Excess adipose tissue seems to impair insulin signaling by inhibiting the phosphorylation of its receptor, resultingin insulin resistance. Studies have evidenced role of vitamin D in mechanisms involved in the pathogenesis of insulin resistance in obesity by acting in improving glycemic control both by increasing hepatic and peripheral glucoseup take and by promoting the secretion of this hormone. CONCLUSIONS: Vitamin D exerts a protective effect in the treatment and prevention of insulin resistance in patients with obesity and protects the body against oxidative stress and chronic inflammation, contributing to glycemic control. Unfortunately, current data related to the effects of vitamin D supplementation on insulin resistance are still inconclusive

Dietary intake of vitamin D and its relation to insulin resistance in obese women / Ingestão dietétíca de vitamina D e sua relação com a resistência à insulina em mulheres obesas

The aim of this study was to assess the relation between dietary intake of vitamin D and insulin resistance in obese and nonobese women. This cross-sectional study included 93 women, aged between 20 and 50 years, who were subdivided into two groups: the obese group (n = 46) and the agematched control group (n = 47). Vitamin D and calcium intake was monitored using 3-day food records and Dietpro software version 5.1. Measurements of serum glucose and serum insulin were based on an enzymatic colorimetric method and a chemiluminescence assay, respectively. Insulin resistance was assessed by means of homeostasis model assessment of insulin resistance (HOMA-IR). The median values of vitamin D content in the diet were found to be lower than those recommended, although there was a significant difference between groups (p < 0.001). The mean values of calcium intake were found to be above the recommendations, although there was no significant difference between the groups (p > 0.05). The values of serum glucose, serum insulin, and HOMA-IR were higher in obese women than in the control group. The correlation analysis indicated that the association between the dietary intake of vitamin D and insulin resistance was not significant. The results of this study indicate that dietary vitamin D does not influence parameters of glycemic control in obese women (AU)

O objetivo do estudo foi avaliar a relação entre a ingestão dietética de vitamina D e resistência à insulina em mulheres obesas e não obesas. Este estudo transversal incluiu 93 mulheres, com idades entre 20 e 50 anos, que foram subdivididos em dois grupos: obesos (n = 46) e o grupo controle pareados por idade (n = 47). A ingestão de vitamina D e cálcio foi estimada por meio dos registros alimentares de 3 dias e analisada pelo software DietPro versão 5.1. As mensurações séricas de glicose e insulina foram baseadas em um método colorimétrico enzimático e um ensaio de quimiluminescência, respectivamente. A resistência à insulina foi avaliada por meio do modelo de avaliação da homeostase da resistência à insulina (HOMA-IR). Os valores médios do teor de vitamina D na dieta foram mais baixos do que os recomendados, embora houvesse uma diferença significativa entre os grupos (p <0,001). Os valores médios de ingestão de cálcio estavam acima das recomendações, apesar de não haver diferença significativa entre os grupos (p> 0,05). Os valores de glicose sérica, insulina sérica, e HOMA-IR foram maiores em mulheres obesas que no grupo de controle. A análise de correlação indicou que a associação entre a ingestão de vitamina D e resistência à insulina não foi significativa. Os resultados deste estudo indicam que a vitamina D na dieta não influencia os parâmetros de controle glicêmico em mulheres obesas (AU)