Role of vitamin D in insulin resistance in obese individuals

Abstract

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. Vitamin D 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 in obese individuals. Methods: It was conducted a search of articles published in PubMED, SciELO, and LILACS database, without limit for the 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, resulting in 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 glucose uptake 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.

Assessment of insulin resistance in patients with primary hyperparathyroidism before and after Parathyroidectomy

“…Vitamin D deficiency and hyperparathyroidism can lead to a decreased calcium levels in serum compared to the normal range 25 . Furthermore, vitamin D deficiency reduces calcium level in peripheral tissues leading to a reduction in insulin secretion from the beta cells of pancreatic and subsequently increases insulin resistance in obese patients 26 …”

“… 25 Furthermore, vitamin D deficiency reduces calcium level in peripheral tissues leading to a reduction in insulin secretion from the beta cells of pancreatic and subsequently increases insulin resistance in obese patients. 26 …”

“…25 Furthermore, vitamin D deficiency reduces calcium level in peripheral tissues leading to a reduction in insulin secretion from the beta cells of pancreatic and subsequently increases insulin resistance in obese patients. 26 In another study, 21 patients with symptoms of PHPT underwent parathyroidectomy. Fasting blood glucose, calcium, phosphorus, plasma insulin and vitamin D were measured at baseline and two months after parathyroidectomy.…”

Association of Serum Calcium and Phosphate Concentrations with Glucose Metabolism Markers: The Furukawa Nutrition and Health Study

“…We further adjusted for work-related physical activity (<3, 3 to <7, 7 to <20, or ≥ 20 METs-h/day), leisure-time physical activity (0, 0.1 to <3, 3 to <10, or ≥10 METs-h/week), smoking status (never-smoker, quitter, current smoker consuming < 20 cigarettes/day, or current smoker consuming ≥ 20 cigarettes/day), alcohol consumption (non-drinker, including infrequent drinker consuming less than one drink per week, drinkers consuming < 23 g of ethanol/day, drinkers consuming ≥ 23 to <46 g of ethanol/day, and drinkers consuming ≥ 46 g of ethanol/day), night or rotating shift work (yes or no), and BMI (kg/m 2 , continuous) in the second model. To assess whether serum calcium and phosphate concentrations were associated with glucose metabolism markers independently of other specific nutrient intakes and risk factors that have been associated with glucose metabolism markers in previous studies [ 19 , 25 , 26 , 27 , 28 ], we further adjusted for logarithmic CRP (mg/dL), serum magnesium (mg/dL), serum ferritin (ng/mL), dietary calcium intake (mg/1000 kcal/day, continuous), and vitamin D intake (mg/1000 kcal/day, continuous) in the third model. Trends for associations of serum calcium, phosphate, and calcium–phosphate product concentrations with glucose metabolism markers were determined by assigning the median value of each exposure quartile to the appropriate category and modeling it as a continuous variable.…”

Interaction between Dietary Fat Intake and Metabolic Genetic Risk Score on 25-Hydroxyvitamin D Concentrations in a Turkish Adult Population

“…Several hypotheses have been proposed to define the potential mechanisms of the associations between metabolic diseases including obesity and one's vitamin D status [69][70][71][72][73][74][75][76][77][78]. These include the volumetric dilution of serum vitamin D levels [68,73,74], adipocyte hypertrophy contributing to overexpression of proinflammatory cytokines [77,79], modifications of vitamin D-related enzymes [75,76] affected by high fat diet-induced obesity, and lower endogenous vitamin D synthesis in the skin as a consequence of less outdoor activity [75,80], less physical activity [71], and less exposure to sunlight in obese individuals [73][74][75][76][77][78][79][80].…”