Adipose tissue is considered an endocrine organ that promotes excessive production of reactive oxygen species when in excess, thus contributing to lipid peroxidation. Magnesium deficiency contributes to the development of oxidative stress in obese individuals, as this mineral plays a role as an antioxidant, participates as a cofactor of several enzymes, maintains cell membrane stability and mitigates the effects of oxidative stress. The objective of this review is to bring together updated information on the participation of magnesium in the oxidative stress present in obesity. We conducted a search of articles published in the PubMed, SciELO and LILACS databases, using the keywords 'magnesium', 'oxidative stress', 'malondialdehyde', 'superoxide dismutase', 'glutathione peroxidase', 'reactive oxygen species', 'inflammation' and 'obesity'. The studies show that obese subjects have low serum concentrations of magnesium, as well as high concentrations of oxidative stress marker in these individuals. Furthermore, it is evident that the adequate intake of magnesium contributes to its appropriate homeostasis in the body. Thus, this review of current research can help define the need for intervention with supplementation of this mineral for the prevention and treatment of disorders associated with this chronic disease.

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Breast cancer is a disease of high mortality, characterized by the progressive accumulation of mutations that contribute to the uncontrolled development of breast tissue cells. Literature shows that disturbances in mineral homeostasis, such as magnesium, may interfere with tumor progression. The objective of this study is to provide updated information about magnesium's role in the pathogenesis of breast cancer. A review of literature was carried out from a search for articles in the PubMed and CAPES Periodicals databases published between 1995 and 2016 with the cross-references of the descriptors "magnesium," "breast neoplasms," and "oxidative stress" and the corresponding words in Portuguese. We included studies on the metabolism and bioavailability of magnesium and studies related to breast cancer and excluded articles in which only the abstract was available, dissertations, theses, articles involving adjuvant and/or neoadjuvant therapies, and supplementation of minerals in breast cancer patients. Magnesium is a mineral that participates in the metabolism of various nutrients and nucleic acids. In the presence of breast cancer, neoplastic cells increase the expression of magnesium transport channels, which raises the intracellular concentration of the mineral, contributing to tumor growth through its function of increasing energy demand. The data obtained in this review illustrates the influence of magnesium on the progression of breast cancer. However, the existing data are scarce and inconsistent, which demonstrates a need for further studies on the subject with a goal to have better control of the disease.

Zinc deficiency compromises its biological functions, its effect on the immune system and its antiviral activity, increasing vulnerability to infectious diseases. This narrative review aims at presenting and discussing functional aspects and possible mechanisms involved in the potential role of zinc in the immune response and antiviral activity for COVID-19 prevention and control. The searches were conducted in PubMed and Science Direct databases, using clinical trials, experimental studies in animals and humans, case-control studies, case series, letters to the editor, and review articles published in English, without restrictions on year of publication. Search approach was based on using the terms: “zinc”, “COVID-19”, “antiviral agents”, “immunologic factors”, and “respiratory tract infections”. Literature shows the importance of zinc as an essential mineral immunomodulator with relevant antiviral activity in the body. Thus, although there is still a scarcity of studies evaluating zinc supplementation in patients with COVID-19, the results on the topic show the necessity of controlling zinc mineral deficiency, as well as maintaining its homeostasis in the body in order to strengthen the immune system and improve the prevention of highly-complex viral infections, such as that of the COVID-19.

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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.

Background: Selenium deficiency appears to limit antioxidant defense in obese individuals. This study evaluated the association between adiposity indices, selenium status, and oxidative stress in obese women. Methods: This was a cross-sectional study involving 139 women who were divided into the following two groups: the case group (obese women, n = 63) and the control group (normal-weight women, n = 76). Plasma, erythrocyte, and urinary selenium levels were determined using inductively coupled plasma optical emission spectrometry. Body weight, height, waist circumference, hip circumference and neck circumference were measured. Body mass index, waist/height ratio, conicity index, body fat index, body adiposity index, body circularity index, and visceral adiposity index were calculated. Plasma levels of thiobarbituric acid reactive substances were determined. The erythrocyte glutathione peroxidase activity was determined using an automatic biochemical analyzer and Ransel kit. Results: Obese women had selenium deficiency characterized by reduction in plasma and erythrocyte concentrations (P < .001). The urinary selenium excretion was higher in the case group compared to the control group (P < .001).Adiposity indices values and plasma concentrations of thiobarbituric acid reactive substances were significantly elevated in obese women (P < .001). There was a significant association between adiposity indices and selenium status (P < .001), and between erythrocyte selenium and erythrocyte glutathione peroxidase activity (P < .001). Conclusion:Obese women evaluated in the study have reduced plasma and erythrocyte concentrations of selenium and an increased urinary excretion of selenium. The correlation analysis reveals an association between intra-abdominal fat accumulation and selenium metabolism and oxidative stress.

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