Magnesium, selenium and zinc deficiency compromises antioxidant defense in women with obesity.

Studies have shown that deficiencies in magnesium, selenium, and zinc in individuals with obesity compromise the endogenous antioxidant defense system. This study aimed to evaluate the impact of mineral deficiency on enzymatic antioxidant defense in women with obesity. The study involved 63 women with obesity (BMI ≥ 35 kg/m2) and 77 eutrophic women (BMI between 18.5 and 24.9 kg/m2). Variables such as fasting glucose, glycated hemoglobin, fasting insulin, and serum lipids were analyzed. Insulin resistance was measured using the homeostasis assessment model (HOMA-IR) and beta cell function using the homeostasis assessment model (HOMA-ß). Dietary intake of energy, macronutrients (including magnesium, zinc, and selenium), and plasma, erythrocyte, and urinary concentrations of these minerals were measured and analyzed. Serum cortisol, plasma leptin, plasma thiobarbituric acid reactive substances, and the activity of erythrocyte superoxide dismutase (SOD), erythrocyte glutathione peroxidase (GPX), and erythrocyte catalase were also analyzed. Women with obesity had reduced plasma and erythrocyte concentrations and greater urinary excretion of all minerals compared to normal weight women (p < 0.05). There was a positive association between erythrocyte concentrations of zinc and selenium and the activity of the GPX and SOD enzymes in erythrocytes in women with obesity (p < 0.05), in addition to a positive association between serum insulin and the enzyme GPX, which is dependent on dietary selenium (p < 0.05). Individuals with obesity are deficient in magnesium, selenium, and zinc, which appears to impair the antioxidant defense system and contribute to important metabolic disorders such as oxidative stress in these patients.

Adipose Tissue Dysfunction: Impact on Metabolic Changes?

Adipose tissue is a metabolically dynamic organ that is the primary site of storage for excess energy, but it serves as an endocrine organ capable of synthesizing a number of biologically active compounds that regulate metabolic homeostasis. However, when the capacity of expansion of this tissue exceeds, dysfunction occurs, favoring ectopic accumulation of fat in the visceral, which has been implicated in several disease states, most notably obesity. This review highlights the mechanisms involved in the structure of adipose tissue, tissue expandability, adipocyte dysfunction, as well as the impact of these events on the manifestation of important metabolic disorders associated with adipose tissue dysfunction. A literature search using Pubmed, Web of Science, Scopus, and Cochrane databases were used to identify relevant studies, 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. The excessive ectopic lipid accumulation leads to local inflammation and insulin resistance. Indeed, overnutrition triggers uncontrolled inflammatory responses white adipose tissue, leading to chronic low-grade inflammation, therefore fostering the progression of important metabolic disorders. Thus, it is essential to advance the understanding of the molecular mechanisms involved in adipose tissue dysfunction in order to mitigate the negative metabolic consequences of obesity.

Antiviral and immunological activity of zinc and possible role in COVID-19.

Zn 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 Zn in the immune response and antiviral activity for coronavirus infectious disease-19 (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 Zn as an essential mineral immunomodulator with relevant antiviral activity in the body. Thus, although there is still a scarcity of studies evaluating Zn supplementation in patients with COVID-19, the results on the topic show the necessity of controlling Zn mineral deficiency, as well as maintaining its homoeostasis 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.

No association between zinc and thyroid activity in obese women.

Obesity is characterized by changes in the metabolism of zinc and thyroid hormones. Studies have also shown the role of zinc in the function and metabolism of thyroid. The present study aimed to evaluate the relationship between serum concentrations of thyroid hormones, dietary zinc intake and zinc distribution in obese women. A case-control study was conducted enrolling 98 women aged between 20 and 50 years old who were divided into case group (BMI ≥ 35 kg/m2) and control group (BMI = 18.5-24.9 kg/m2). Patients underwent anthropometric measurements and analysis of dietary zinc intake, which was performed by a three-day food record. Zinc concentrations in plasma and erythrocytes were determined by inductively coupled plasma optical emission spectrometry. Serum concentrations of thyroid hormones and antibodies were determined by chemiluminescence. Mean values of dietary zinc intake were higher than recommended (10.37 ± 3.12 mg/day and 11.37 ± 4.36 mg/day for control and obeses, respectively). Obese women had reduced plasma (67.22 ± 5.96 µg/dL) and erythrocyte (37.16 ± 3.64 µg Zn/gHb) zinc concentrations when compared to the control group (plasma: 89.71 ± 13.33 µg/dL; erythrocyte: 42.68 ± 3.73 µg Zn/gHb) (p < 0.001). Serum TSH (control: 2.62 ± 1.29 µIU/mL; obeses: 3.08 ± 1.13 µIU/mL), Free T3 (control: 2.19 ± 0.63 pg/dL; obeses: 2.09 ± 0.34 pg/dL), and Free T4 (control: 1.12 ± 0.31 ng/dL; obeses: 1.09 ± 0.19 ng/dL) concentrations were within the normal range in both groups, without significant difference between them (p > 0.05). There was no correlation between thyroid hormone concentrations and zinc parameters (p > 0.05). Although obese women presented hypozincemia, they had normal levels of thyroid hormones and no correlation was found between the studied parameters.

Zinc gluconate supplementation impacts the clinical improvement in patients with ulcerative colitis.

Ulcerative colitis is an inflammatory bowel disease that affects the mucous membrane of the colon. The pathogenesis is not clear, but there is evidence of a complex interaction between genetic, environmental, and immunological factors. In this regard, we highlight the role of zinc in the immune system and probable control of the disease. This study evaluated the effect of zinc supplementation on the inflammatory response in patients with ulcerative colitis. A blind interventional study involving 41 patients of both sexes, who underwent either zinc gluconate supplementation (n = 23), or treatment with a placebo (corn starch) (n = 18). Patients were evaluated for dietary zinc intake, plasma and erythrocyte zinc concentrations, and serum levels of Th1/Th2/Th17 type cytokines at baseline (T0) and 30 (T1) and 60 (T2) days after intervention. Patients in the zinc supplementation group had a lower probability of having an adequate zinc intake than placebo. In this same group, there was a significant difference between plasma zinc concentrations (T1 in relation to T0, T2 in relation to T1, and T2 in relation to T0) and erythrocyte zinc (T1 in relation to T0 and T2 in relation to T1). Zinc supplementation resulted in significant changes in the concentrations of IL-2 and IL-10 without differences in the other interleukins. Zinc gluconate intervention in patients with ulcerative colitis improves the nutritional status of this mineral in these patients and positively influences their clinical outcome, reinforcing the role of zinc as an important dietary component in disease control.

No Relation Between Zinc Status and Inflammatory Biomarkers in Adolescent Judokas.

This study aimed to assess the relation between zinc status and inflammation biomarkers in adolescent judokas. This cross-sectional study included 52 male adolescents, aged between 14 and 19 years, who were subdivided into two groups: judoka group (n = 25) and control group (n = 27). Zinc intake was monitored using 3-day food records and the NutWin software version 1.5. The plasma and erythrocyte zinc concentrations were determined by flame atomic absorption spectrophotometry. Analysis of cytokines (IL-1ß, IL-6, and TNF-α) was performed. The mean values of zinc concentration in the diet were found to be higher than those recommended (11.0±3.9 mg/day and 20.3±11.9 mg/day for control group and judokas, respectively) although there was no significant difference between the groups. The mean plasma concentrations of zinc were below the reference range (71.4±16.0 µg/dL and 71.9±13.8 µg/dL for control group and judokas, respectively), without a significant difference between the groups. The mean concentrations of zinc erythrocyte were within the reference range (41.2±8.6 µg/gHb and 42.6±11.3 µg/gHb for control group and judokas, respectively), without a significant difference between the groups. There was no significant difference in the inflammatory biomarkers between the judokas and controls. There was not a significant correlation between biochemical parameters of zinc and inflammation biomarkers in adolescent judokas. Regarding the data found in the study, it can be concluded that the athletes evaluated have low plasma zinc concentrations, normal erythrocyte values, and high dietary intake of zinc. Moreover, the study don't show a relationship between zinc parameters and inflammatory markers evaluated.

Nutritional status of selenium in overweight and obesity: A systematic review and meta-analysis.

BACKGROUND & AIMS: Selenium is an antioxidant and anti-inflammatory nutrient and regulates important physiological processes, such as carbohydrate and lipid metabolism, immune system actions, and adipocyte differentiation. Given these important functions, several studies have assessed the nutritional status of selenium to elucidate whether its homeostasis is impaired by excess adiposity, which in turn could contribute to the adipose tissue dysfunction and metabolic disorders. However, the results of these studies are quite controversial. Therefore, this systematic review and meta-analysis aimed to assess differences in the nutritional status of selenium in overweight/obese individuals. METHODS: We searched the PubMed, Scopus, Web of Science, Embase, Cochrane Library, and Virtual Health Library databases. Studies comparing overweight or obese individuals with eutrophic individuals and assessing at least one marker of selenium were included. Comprehensive Meta-Analysis software was used to perform meta-analysis. The effect size was calculated using the raw mean difference or the standardized mean difference, with 95% confidence interval and a p-value of <0.05. Heterogeneity was determined using the I2 index. Subgroup analyses were performed according to sex, body mass index (BMI), and selenium content in the soil. The protocol of this review was registered in the Prospective Register of Systematic Reviews (registration number: CRD42020185405). RESULTS: This systematic review included 73 articles, of which 65 articles were eligible for meta-analysis. There were no significant differences between the overweight/obesity and eutrophy groups in terms of dietary intake and plasma/serum levels of selenium and selenoprotein P levels. The activity of plasma/serum glutathione peroxidase was decreased in the overweight/obese children and adolescents; however, the difference was no statistically significant when the enzyme activity was analyzed in erythrocytes and whole blood. In the adult age group, overweight/obese individuals had decreased activity of both glutathione peroxidase isoforms compared to those individuals with eutrophy. In particular, the activity of erythrocyte glutathione peroxidase was significantly decreased in obese individuals and those living in regions with low-to-moderate selenium content in the soil. Regarding selenium excretion markers, overweight/obese individuals had lower levels of selenium in the urine and nails and a trend of higher levels of selenium in the hair than eutrophic individuals. CONCLUSIONS: In conditions of excess adiposity, the main alteration in the nutritional status of selenium is a decrease in glutathione peroxidase activity, particularly in adults with obesity. In addition, reduced levels of selenium in urine and nails can be found in overweight or obese individuals.

Relationship between zinc-related nutritional status and the progression of multiple sclerosis.

BACKGROUND: Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system. OBJECTIVE: To investigate plasma and erythrocyte zinc status and its relationship to MS. METHODS: Cross-sectional study, including 98 participants, distributed in groups: case (MS, n = 49), diagnosed with MS and control (n = 49), matched by age and sex with the case group. Zinc was analyzed by flame atomic absorption spectrophotometry, and superoxide dismutase (SOD) activity by spectrophotometry. RESULTS: Mean plasma zinc was 94.6 (22.1) µg/dL for MS patients and 81.5 (31.3) µg/dL for control group, with statistical difference (p = 0.023). The mean erythrocyte zinc was 83.6 (41.6) µg/gHb for case group and 72.6 (31.5) µg/gHb for control. Erythrocyte SOD activity was above reference values, significantly different for MS patients (p = 0.003). There was a significant direct correlation between erythrocyte zinc and SOD (r = 0.835; p < 0.001). SOD showed inverse correlation with MS outbreaks (r = -0.317; p = 0.027). CONCLUSION: Patients with MS have normal plasma and elevated erythrocyte zinc. Erythrocyte zinc showed positive correlation with SOD, which correlated inversely to outbreaks.

Selenium status and its relationship with thyroid hormones in obese women.

BACKGROUND AND AIMS: Studies have been conducted with the purpose of elucidating thyroid gland dysfunction in obesity, however the contributing factors for such dysfunction are not yet fully understood. Selenium is notable for its role in thyrocyte protection against oxidative damage and control of thyroid hormone synthesis. In addition, subjects with obesity may exhibit alterations in the selenium homeostasis. Therefore, the present study aimed to examine the selenium status and its relationship with serum thyroid hormone levels in obese women. METHODS: This cross-sectional study included 69 euthyroid women, aged between 18 and 50 years, who were divided in two groups: an obese group (n = 35) and a control group with women of normal weight (n = 34). Selenium intake was assessed by three-day diet records and analyzed using NutWin software version 1.5. Plasma, erythrocyte, and urinary selenium levels were determined using inductively coupled plasma optical emission spectrometry. Testing for thyroid hormones and thyroid autoantibodies was performed based on chemiluminescence. RESULTS: The median dietary selenium content was adequate according to the recommendations, with no statistical difference between groups. Obese women had reduced plasma and erythrocyte selenium levels compared to the control group, although selenium concentration in erythrocytes was adequate within the normal range for both groups. There was no significant difference between the urinary selenium concentrations in the subjects; however, the mineral clearance was higher in the obese group. Free triiodothyronine (fT3) and free thyroxine (fT4) levels were higher in obese women with class II obesity when compared to the control group. There was a negative correlation between plasma selenium and serum fT4 levels. CONCLUSIONS: Obese women showed impairment in selenium homeostasis, however, this fact did not seem to adversely affect thyroid metabolism.

Hypomagnesemia and Its Relationship with Oxidative Stress Markers in Women with Breast Cancer.

Reduced serum magnesium concentrations in women with breast cancer compromises one of the antioxidant defense system involved in the carcinogenesis process. To evaluate parameters of magnesium, the enzyme activity of superoxide dismutase, and its relation with oxidative stress markers in women with breast cancer. A case-control study was conducted, involving 60 women in the age range between 29 and 65 years, divided into two groups: women with breast cancer (n = 30) and women without breast cancer (n = 30). Plasma; ionized, erythrocytic, and urinary magnesium intake; plasma concentrations of thiobarbituric acid reactive substances; and erythrocyte superoxide dismutase enzyme activity were evaluated. The mean value of the amount of dietary magnesium was below the recommended level in both groups studied, with no statistical difference (p > 0.05). Plasma, ionized, and erythrocyte magnesium concentrations of women with breast cancer were reduced in relation to the control group (p < 0.0001) and inadequate according to the reference values. Urinary excretion was high, with a significant difference between groups (p < 0.0001). The mean concentration of thiobarbituric acid reactive substances was high in the study participants, with no significant statistical difference between the groups (p > 0.05). The mean values of superoxide dismutase enzyme activity were adequate, with no statistically significant difference between the groups (p > 0.05). Women with breast cancer have impaired magnesium homeostasis, characterized by its reduction in diet, plasma, and erythrocytes and its increase in urine.

Expression of metalloproteinases 2 and 9 and plasma zinc concentrations in women with fibroadenoma.

OBJECTIVE: This study aims to investigate the association between the immunohistochemical expression of matrix metalloproteinase-2 and matrix metalloproteinase-9 and plasma zinc in women with fibroadenoma. METHODS: This cross-sectional study included 37 premenopausal women with fibroadenoma. Waist circumference and body mass index of the participants were measured. Plasma zinc concentrations were determined using atomic flame absorption spectrophotometry. Fragments of breast tissue were fixed and incubated with primary mouse monoclonal antibodies (monoclonal antibodies matrix metalloproteinase -2 -507 and monoclonal antibodies matrix metalloproteinase -9-439). Semi-quantitative analysis of matrix metalloproteinase-2 and matrix metalloproteinase-9 immunoreactivity was performed. Spearman's test and Friedman's test were used for statistical analyses. The p<0.05 were considered statistically significant. RESULTS: The average age of the participants was 32.81±9.51 years. The body mass index and waist circumference values were within the normal range. The mean plasma zinc concentration was 42.73±13.84 µg/dL, with 94.6% inadequacy. A statistically significant difference was found between the positive expression of matrix metalloproteinase-2 and matrix metalloproteinase-9 (p=0.0184). There was no significant correlation between the matrix metalloproteinase expression and the plasma zinc levels. CONCLUSIONS: Women with fibroadenoma had hypozincemia and positive expression of metalloproteinases.

Nutritional status and vitamin A and zinc levels in patients with kala-azar in Piauí, Brazil.

INTRODUCTION: Malnutrition and kala-azar (or visceral leishmaniasis) are significant public health problems in different parts of the world. Immunity and susceptibility to infectious and parasitic diseases are directly linked to the host's nutritional state, but little is known about the interaction between nutrition and kala-azar. This study aimed to evaluate nutritional status with kala-azar and correlate these findings with the clinical and laboratory manifestations of the disease, and zinc and retinol levels. METHODS: This was a cross-sectional study of 139 patients with kala-azar. Nutritional status classification was performed according to international recommendations. Parametric or nonparametric tests were applied whenever indicated in a two-sided test with a 5% significance level. RESULTS: Weight loss and malnutrition were more frequent in adults. Body mass index-for-age, fat area of the arm, and upper arm muscle area were significantly associated with probability of death. The presence of human immunodeficiency virus, hepatomegaly, and splenomegaly was correlated with nutritional assessment. Blood leukocyte and lymphocyte, serum creatine, and vitamin A levels were significantly higher in adult men. Vitamin A levels were highly associated with the level of hemoglobin and C-reactive protein (CRP) in multivariate analysis. All patients had reduced plasma zinc levels, but this finding had no association with the outcome variables. CONCLUSIONS: Malnutrition was correlated with severe disease and was more prevalent in older people with kala-azar. Vitamin A deficiency was associated with hemoglobin and CRP. Zinc levels were reduced in patients with kala-azar.

Relationship between selenium status and biomarkers of oxidative stress in Crohn's disease.

OBJECTIVE: Crohn disease (CD) is characterized by chronic intestinal inflammation and various factors involved in its pathogenesis including oxidative stress. The oxidative stress in CD may compromise antioxidant nutrients, such as selenium. The aim of this study was to assess the status of selenium and its relationship with markers of oxidative stress in patients with CD in comparison to controls. METHODS: The study included 47 patients with CD (20 with active disease and 27 in remission) and 25 healthy individuals. Blood samples were collected for the analysis of plasma and erythrocyte selenium concentrations using inductively coupled plasma optical emission spectrometry (ICP-OES). Selenoprotein P (SepP) was evaluated by sandwich enzyme-linked immunosorbent assay, erythrocyte glutathione peroxidase (GPx1) activity was assessed by using an automatic biochemistry analyzer, and the concentration of thiobarbituric acid reactive substances (TBARS) was measured. Comparative analyses were performed using one-way analysis of variance and Tukey's post hoc test. For correlations, Pearson's coefficient test was used. The determinants for CD and lipid peroxidation were indicated by odds ratio. RESULTS: Plasma and erythrocyte selenium levels and SepP concentrations were lower in the CD patient groups than in the healthy group. GPx1 activity and the concentration of TBARS were significantly higher in the CD groups. In the univariate analysis, plasma and erythrocyte selenium and TBARS were associated with CD. CONCLUSION: Patients with CD have impaired selenium status, which is related to the increased oxidative stress observed in these patients.

Zinc and Insulin Resistance: Biochemical and Molecular Aspects.

Studies have shown the participation of minerals in mechanisms involved in the pathogenesis of insulin resistance. Zinc, in particular, seems to play an important role in the secretion and action of this hormone. Therefore, the aim of this review is to understand the role of zinc in increasing insulin sensitivity. We conducted a search of articles published in the PubMed and ScienceDirect database selected from March 2016 to February 2018, using the keywords "zinc," "insulin," "insulin resistance," "insulin sensitivity," and "supplementation." Following the eligibility criteria were selected 53 articles. The scientific evidences presented in this review show the importance of zinc and their carrier proteins in the synthesis and secretion of insulin, as well as in the signaling pathway of action of this hormone. Zinc deficiency is associated with glucose intolerance and insulin resistance; however, the effectiveness of the intervention with the zinc supplementation is still inconclusive.

The effect of Roux-en-Y gastric bypass on zinc nutritional status.

BACKGROUND: Researchers have found that zinc nutritional status in obese and diabetic subjects is altered: low zinc concentrations in plasma and erythrocytes, with high urinary zinc excretion, were observed. This study evaluated the effect of Roux-en-Y gastric bypass (RYGBP) on plasma, erythrocyte and urinary zinc concentration. METHODS: 22 morbidly obese patients were studied before and 6 months after RYGBP. Fasting blood sample and 24-hour urine were collected in the pre- and postoperative phases. A software analyzed the diet information from 3-day food records after RYGBP. Zinc nutritional status was evaluated by determination of the concentration of this mineral in plasma and erythrocytes, and the urinary excretion of zinc / 24 hours by atomic absorption spectrophotometry. RESULTS: The diets consumed by the patients had adequate average concentrations of zinc. Zinc concentration in plasma, erythrocytes and urine were within the values of normality before RYGBP, with mean values of 93.25 +/- 19.34 microg/dL, 43.85 +/- 7.76 microg Zn/gHb and 583.05 +/- 359.30 microg Zn/24 hours, respectively. At 6 months after RYGBP, there was a change in these parameters to 69.82 +/- 10.95 microg/dL, 51.80 +/- 6.92 microg Zn/gHb, 535.29 +/- 216.40 microg Zn/24 hours in the concentration of plasma, erythrocyte and urinary zinc. CONCLUSION: These results suggest that RYGBP promoted, besides change in body composition, an alteration in the zinc plasma and erythrocytes concentrations which in the medium and long term, could cause problems for these patients.

Zinc nutritional status in adolescents with Down syndrome.

Studies have evidenced that zinc metabolism is altered in presence of Down syndrome, and zinc seems to have a relationship with the metabolic alterations usually present in this syndrome. In this work, the Zn-related nutritional status of adolescents with Down syndrome was evaluated by means of biochemical parameters and diet. A case-control study was performed in a group of adolescents with Down syndrome (n = 30) and a control group (n = 32), of both sexes, aged 10 to 19 years. Diet evaluation was accomplished by using a 3-day dietary record, and the analysis was performed by the NutWin program, version 1.5. Antropometric measurements were performed for evaluation of body composition. The Zn-related nutritional status of the groups was evaluated by means of zinc concentration determinations in plasma and erythrocytes, and 24-h urinary zinc excretion, by using the method of atomic absorption spectroscopy. The diet of both groups presented adequate concentrations of lipids, proteins, carbohydrates, and zinc. The mean values found for zinc concentration in erythrocytes were 49.2 +/- 8.5 microg Zn/g Hb for the Down syndrome group and 35.9 +/- 6.1 microg Zn/g Hb for the control group (p = 0.001). The average values found for zinc concentration in plasma were 67.6 +/- 25.6 microg/dL for the Down syndrome group and 68.9 +/- 22.3 microg/dL for the control group. The mean values found for zinc concentration in urine were 244.3 +/- 194.9 microg Zn/24 h for the Down syndrome group and 200.3 +/- 236.4 microg Zn/24 h for the control group. Assessment of body composition revealed overweight (26.7%) and obesity (6.6%) in the Down syndrome group. In this study, patients with Down syndrome presented altered zinc levels for some cellular compartments, and the average zinc concentrations were low in plasma and urine and elevated in erythrocytes.

Urinary excretion of zinc and metabolic control of patients with diabetes type 2.

The objective of this study was to assess urinary excretion of zinc and evaluation parameters of metabolic control in type 2 diabetic patients. Thirty-one type 2 diabetic patients, of both genders, with 5.8 +/- 5.6 years average time of the disease, age range 20-60 years, were selected. Evaluation of the nutritional status was performed using anthropometric measurements. To evaluate food consumption, the 3-day alimentary log method was used, and its analysis was performed using a software. Determination of urinary zinc was by atomic absorption spectrophotometry. From the obtained results, it was concluded that 51.6% of the patients were overweight. The mean of found waist circumference was 100.4 and 92.2 cm for men and women, respectively. Blood glucose and glycated hemoglobin values were higher than reference values, and plasma albumin concentration was adequate. The median of found urinary zinc excretion was 474.9 mug/24 h, within normal standards (300-600 mug/day). Regarding diet composition, calorie and protein concentration were above recommendation, while mean zinc concentration was adequate. This data allow the conclusion that the evaluated patients presented adequate urinary zinc excretion in comparison with reference values.

The Effect of Zinc Supplementation on Insulin Resistance in Obese Subjects: a Systematic Review.

Obesity is a chronic disease characterized by excessive accumulation of body fat and the presence of metabolic disorders such as insulin resistance. In this sense, zinc is an important nutrient that stimulates insulin secretion and increases sensitivity to insulin. The aim of this study was to investigate the effect of zinc supplementation on insulin resistance in obese subjects through a systematic review of the available clinical trials. The search for articles was conducted using the PubMed, SciVerse Scopus, SciVerse ScienceDirect, and Cochrane databases, on May 25, 2016, by two authors independently. The recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) were followed in the conduct of this review. The Cochrane Collaboration tool was used to assess the risk of bias of the trials included in this review. After screening of the articles, six clinical trials were included in this systematic review. The scientific evidence presented in this systematic review shows that zinc supplementation improves insulin resistance in obese individuals of both sexes.

Zinc and Oxidative Stress: Current Mechanisms.

Oxidative stress is a metabolic dysfunction that favors the oxidation of biomolecules, contributing to the oxidative damage of cells and tissues. This consequently contributes to the development of several chronic diseases. In particular, zinc is one of the most relevant minerals to human health, because of its antioxidant properties. This review aims to provide updated information about the mechanisms involved in the protective role of zinc against oxidative stress. Zinc acts as a co-factor for important enzymes involved in the proper functioning of the antioxidant defense system. In addition, zinc protects cells against oxidative damage, acts in the stabilization of membranes and inhibits the enzyme nicotinamide adenine dinucleotide phosphate oxidase (NADPH-Oxidase). Zinc also induces the synthesis of metallothioneins, which are proteins effective in reducing hydroxyl radicals and sequestering reactive oxygen species (ROS) produced in stressful situations, such as in type 2 diabetes, obesity and cancer. Literature provides strong evidence for the role of zinc in the protection against oxidative stress in several diseases.

Hypomagnesemia and its relation with chronic low-grade inflammation in obesity.

INTRODUCTION:: The accumulation of visceral fat in obesity is associated with excessive production of proinflammatory adipokines, which contributes to low-grade chronic inflammation state. Moreover, the literature has shown that mineral deficiency, in particular of magnesium, has important role in the pathogenesis of this metabolic disorder with relevant clinical repercussions. OBJECTIVE:: To bring updated information about the participation of hypomagnesemia in the manifestation of low-grade chronic inflammation in obese individuals. METHOD:: Articles published in PubMed, SciELO, LILACS and ScienceDirect, using the following keywords: "obesity," "magnesium" and "low grade inflammation." RESULTS:: Scientific evidence suggests that magnesium deficiency favors the manifestation of low-grade chronic inflammation in obese subjects. CONCLUSION:: From literature data, it is evident the participation of magnesium through biochemical and metabolic reactions in protecting against this metabolic disorder present in obesity.