Zinc status in plasma of obese individuals during glucose administration

Zinc homeostasis and redox alterations in obesity

Impairment of both cellular zinc and redox homeostasis is a feature of several chronic diseases, including obesity. A significant two-way interaction exists between redox metabolism and the relatively redox-inert zinc ion. Redox metabolism critically influences zinc homeostasis and controls its cellular availability for various cellular functions by regulating zinc exchange from/to zinc-binding proteins. Zinc can regulate redox metabolism and exhibits multiple pro-antioxidant properties. On the other hand, even minor disturbances in zinc status and zinc homeostasis affect systemic and cellular redox homeostasis. At the cellular level, zinc homeostasis is regulated by a multi-layered machinery consisting of zinc-binding molecules, zinc sensors, and two selective families of zinc transporters, the Zinc Transporter (ZnT) and Zrt, Irt-like protein (ZIP). In the present review, we summarize the current state of knowledge on the role of the mutual interaction between zinc and redox homeostasis in physiology and pathophysiology, pointing to the role of zinc in the alterations responsible for redox stress in obesity. Since zinc transporters primarily control zinc homeostasis, we describe how changes in the expression and activity of these zinc-regulating proteins are associated with obesity.

The Association between Index of Nutritional Quality (INQ) and Obesity: Baseline Data of Kharameh Cohort

Obesity is an increasing problem that can lead to noncommunicable diseases. The role of dietary factors on one's obesity is confirmed in many studies. One nutritional approach that can be used for assessment of the foods and diets is the Index of Nutritional Quality (INQ). Our study is aimed at exploring the association between INQ and obesity. Our hypothesis is that enriched and high-quality diets reduce the risk of overweight or obesity. This study was carried out on 6248 overweight and obese participants, from whom 4356 (69.7%) and 1892 (30.3%) were overweight and obese, respectively. To assess the dietary intake for the participants, a valid food frequency questionnaire (FFQ) with 130 food items was utilized. The analysis revealed an inverse association between the overweight and the INQ of iron, thiamin, riboflavin, B6, folate, zinc, magnesium, calcium, and vitamin C and E. For the obese group, this inverse association was found for iron, B6, folate, zinc, magnesium, calcium, and vitamin C and E. These results approved our hypothesis that a rich nutrition diet may lead to a lower risk of obesity.

Third reported case of rare necrolytic migratory erythema associated with bacteraemia due to severe zinc deficiency after revisional Roux-En-Y gastric bypass: case report and literature review

INTRODUCTION

Obesity is a risk factor for zinc deficiency. After bariatric surgery, non-compliance to diet/vitamin supplements, surgical complications leading to vomiting/diarrhea, poor follow-up and malabsorption can precipitate or exacerbate pre-existing zinc deficiency.

CASE REPORT

We report a patient with rare necrolytic migratory erythema associated with bacteraemia due to severe zinc deficiency after revisional Roux-en-Y gastric bypass (following primary laparoscopic sleeve gastrectomy).

CONCLUSION

Bariatric teams should screen patients before bariatric surgery for nutritional deficiencies and continue surveillance of their nutritional status after surgery. They should maintain a high index of suspicion for zinc deficiency in patients with skin rash after bariatric surgery.

LEVEL OF EVIDENCE

Level V, case report.

Nutritional Management in Bariatric Surgery Patients

The obesity epidemic, mainly due to lifestyle changes in recent decades, leads to serious comorbidities that reduce life expectancy. This situation is affecting the health policies of many nations around the world. Traditional measures such as diet, physical activity, and drugs are often not enough to achieve weight loss goals and to maintain the results over time. Bariatric surgery (BS) includes various techniques, which favor rapid and sustained weight loss. BS is a useful and, in most cases, the best treatment in severe and complicated obesity. In addition, it has a greater benefit/risk ratio than non-surgical traditional therapies. BS can allow the obese patient to lose weight quickly compared with traditional lifestyle changes, and with a greater probability of maintaining the results. Moreover, BS promotes improvements in metabolic parameters, even diabetes remission, and in the quality of life. These changes can lead to an increase of life expectancy by over 6 years on average. The nutrition of people before and after BS must be the subject of indications from a trained staff, and patients must be followed in the subsequent years to reduce the risk of malnutrition and the associated problems. In particular, it is still debated whether it is necessary to lose weight prior to surgery, a procedure that can facilitate the surgeon's work reducing the surgical risk, but at the same time, lengthens preparation times increasing the risks associated with concomitant pathologies. Furthermore, preventing nutritional deficiencies prior to the intervention can improve the results and reduce short- and long-term mortality.

Beneficial effects of Se/Zn co-supplementation on body weight and adipose tissue inflammation in high-fat diet-induced obese rats

This research investigated the effect of co-supplementation of selenium with zinc on weight control and the inflammatory and oxidative status in relation to obesity. Male Wistar rats (N = 32) were randomly divided into four groups after induction of obesity model: 1) "Zn" was supplemented with zinc sulfate (15 mg/kg BW), 2) "Se" supplemented with selenium as sodium selenate (0.5 mg/kg BW), 3) "Zn + Se" which received Zn (15 mg/kg BW) + Se (0.5 mg/kg BW), and 4) "HFD" as the control group. The intervention was done for eight weeks. At the end of treatment, serum and tissue level of Zn, Se, SOD, GSH-Px, MDA, leptin, TNF-α, and IL-6 was evaluated. Weight and food intake were significantly reduced in the Se group(p < .001), while in the Zn group, weight gain due to obesity was prevented compared to the control group (p = .48). There was a significant and stronger increase in SOD, GSH-Px levels and a remarkable decrease in MDA, leptin, TNF-α, and IL-6 in the group receiving the combination of two supplements than either alone(p < .001). Leptin had a positive correlation with inflammatory factors and lipid peroxidation marker and showed an inverse relationship with Zn and Se levels and anti-oxidative enzymes(p < .05). The analysis showed the mediating role of leptin in the effects of zinc. Co-supplementation of selenium and zinc may have a synergistic effect in reduction of oxidative and inflammatory markers. Regarding the effect of zinc on inflammatory factors and lipid peroxidation, leptin can play a mediating role.

The association between deficiency of nutrient intake and resting metabolic rate in overweight and obese women: a cross-sectional study

OBJECTIVE

The double burden of malnutrition is an emerging public health concern nowadays which a correlation with obesity. This study aimed to examine the relationship between resting metabolic rate (RMR) and dietary intake of zinc, vitamin C, and riboflavin in overweight and obese women.

RESULTS

The RMR/FFM showed a significant association with riboflavin (β = 1.59; 95% CI 1.04-23.26, P = 0.04) and zinc (β = 0.78; 95% CI 1.04-4.61, P = 0.03) in the crude model. Moreover, differences in vitamin C and RMR/FFM was marginal significant (β = 0.75; 95% CI 0.95-4.77, P = 0.06). After adjusting for confounders the riboflavin association change to marginal significance (β = 1.52; 95% CI 0.91-23.04, P = 0.06). After controlling for potential confounders, the associations change between zinc and RMR/FFM (β = 0.66; 95% CI 0.78-4.86, P = 0.15) and between RMR/FFM and vitamin C (β = 0.48; 95% CI 0.66-3.96, P = 0.28). Our study showed a significant association between dietary intake of zinc, riboflavin, and vitamin C and change in RMR/FFM in overweight and obese women.

Index of Nutritional Quality (INQ) and the Risk of Obesity in Male Adolescents: a Case-Control Study

Dietary factors may play a key role in the etiology of obesity. The Index of Nutritional Quality (INQ) provides a comprehensive overview of the nutrients content of the diet. This study aimed to investigate the association between INQ and obesity in male adolescents. We hypothesize that receiving a high-quality diet reduces the risk of overweight or obese. This study was carried out on 214 obese/overweight as the case group and 321 normal-weight male adolescents as the control group. Dietary intakes of the participants were collected using a food frequency questionnaire (FFQ). The FFQ-derived dietary data were used to calculate the INQ scores. After adjustments for age and height, an inverse association was found between obesity and INQ of iron, vitamin B6, and magnesium, and a positive association was found between obesity and INQ of zinc (all P < 0.05). After further adjustments for nutritional knowledge and calorie intake, an inverse association was observed between obesity and INQ of vitamin C, iron, vitamin B6, pantothenic acid, selenium, and magnesium (all P < 0.05). The positive association of obesity and INQ of zinc remained significant after adjustments. A higher intake of vitamin C, iron, vitamin B6, pantothenic acid, selenium, and magnesium and a lower intake of zinc may be protective against adolescent obesity. More longitudinal studies are required to investigate the relationship between these nutrients and obesity.

Malnutrition in obesity before and after bariatric surgery

Bariatric surgeries are considered the only effective way of weight loss therapy in morbidly obese patients, i.e. body mass index ≥ 35. However, micronutrient deficiencies and malnutrition are common after most bariatric procedures and thus, pre- and postoperative nutritional assessment and corrections are advised. The present review is presented in an effort to describe in some detail about prevalence, and mechanisms of macro- and micronutrient deficiencies in obese and post-bariatric surgery individuals. We also aimed to summarize the data on screening and supplementation of macro- and micronutrients before and after bariatric surgeries.

[Association between serum zinc level and hypercholesterolemia and insulin resistance in Brazilian children]

The objective of the study was to assess the association between serum zinc level and cardiometabolic factors in prepubertal Brazilian children. This was a cross-sectional study in a representative sample of schoolchildren 8 to 9 years of age in public and private urban schools in Viçosa, Minas Gerais State, Brazil. Body composition was assessed with dual-energy x-ray absorptiometry. The study measured serum glucose, insulin, total cholesterol, high and low density lipoprotein cholesterol, triglycerides, apolipoproteins A (Apo A) and B, uric acid, leptin, homocysteine, ultrasenstive C-reactive protein, and serum zinc. Arterial pressure was measured with automatic inflation equipment. Zinc deficiency was observed in 1.3% of the children. Girls showed the worst cardiometabolic profile, with higher prevalence of increased android fat, triglycerides, insulin resistance, leptin, zinc, and Apo A. In the first tertile of serum zinc concentration, prevalence of insulin resistance was 96% higher (PR = 1.96; 95%CI: 1.04-3.66) and hypercholesterolemia was 23% lower (PR = 0.77; 95%CI: 0.61-0.96) than in the reference category (grouped 2nd and 3rd tertiles of serum zinc concentration). Despite the low prevalence of zinc deficiency, insulin resistance was more prevalent in children in the lowest third of serum zinc concentration. It is important to prevent cardiometabolic alterations in childhood, especially insulin resistance, with an emphasis on serum zinc level.

Association Between Antioxidant Intake/Status and Obesity: a Systematic Review of Observational Studies

The global prevalence of obesity has doubled in recent decades. Compelling evidences indicated that obesity was associated with lower concentrations of specific antioxidants which may play a role in the development of obesity-related diseases such as cardiovascular disease. The present review aimed to synthesize the evidence from studies on the association between obesity and antioxidant micronutrients in a systematic manner. Data bases including MEDLINE, Science Direct, and Cochrane were searched from inception to October 2015. Thirty-one articles were reviewed using the MOOSE checklist. Lower concentrations of antioxidants have been reported in obese individuals among age groups worldwide. Circulatory levels of carotenoids, vitamins E and C, as well as zinc, magnesium, and selenium were inversely correlated with obesity and body fat mass. However, studies demonstrated inconsistencies in findings. Lower status of carotenoids, vitamins E and C, zinc, magnesium, and selenium appears to be associated with adiposity. Intervention studies may be needed to establish the causality of these associations.

Effects of zinc supplementation on obesity: study protocol for a randomized controlled clinical trial

BACKGROUND

The prevalence of obesity is escalating alarmingly worldwide, and it is now becoming a rapidly growing epidemic in developing countries. Recent studies have reported that zinc has been implicated in altered lipid markers, insulin resistance and some obesity markers. There is a lack of evidence on zinc as a potential therapeutic agent to reduce weight and improve metabolic parameters in obese adults. The present study is designed to evaluate the effects of zinc supplementation on obese adults in Sri Lanka. Furthermore, we aim to evaluate the effects of zinc supplementation on metabolic parameters in this population.

METHODS/DESIGN

This study will be conducted as a randomized, double-blind, placebo-controlled clinical trial for a period of 3 months at the clinical laboratory, Department of Applied Nutrition, Wayamba University of Sri Lanka to assess the efficacy of daily zinc 20 mg supplementation in obese subjects. There will be a total of 80 subjects, aged between 18-60 years, of both genders, who are obese (body mass index (BMI) ≥25). Subjects will be stratified according to age, gender and BMI and randomly assigned into the test and placebo groups in a 1:1 ratio. The treatment drug is a capsule containing elemental zinc 20 mg as the active ingredient (as zinc sulphate). The placebo capsule will contain lactose monohydrate. The subjects will receive either zinc capsules or placebo daily for 3 months. The study treatments will be double blinded to both investigator and subject. The visits and the evaluations will be as follows: screening (visit 0), baseline (visit 1) and 3 month (visit 2). The primary outcome will be weight reduction among the obese subjects. Secondary outcome measures include glycaemic status (fasting blood glucose), lipid parameters (total cholesterol, triglyceride levels, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol) and blood pressure.

DISCUSSION

The trial protocol will aim to establish the effects of zinc supplementation on weight reduction and metabolic risk parameters among obese subjects.

TRIAL REGISTRATION

Sri Lanka Clinical Trials Registry: SLCTR/2014/020 . Registered on 18 September 2014.

Zinc transporter 7 deficiency affects lipid synthesis in adipocytes by inhibiting insulin-dependent Akt activation and glucose uptake

Mice deficient for zinc transporter 7 protein (ZnT7) are mildly zinc deficient with low body weight gain and body fat accumulation. To investigate the underlying mechanism of ZnT7 deficiency in body adiposity, we examined fatty acid composition and insulin sensitivity in visceral (epididymal) and subcutaneous fat pads from Znt7 knockout and control mice. We showed that ZnT7 deficiency had adverse effects on fatty acid metabolism and insulin action in subcutaneous fat but not in epididymal fat in mice, consistent with the ZnT7 protein expression pattern in adipose tissues. Importantly, we found that the expression of ZnT7 protein was induced by lipogenic differentiation and reached a peak when the adipocyte was fully differentiated in mouse 3T3-L1 adipocytes. We demonstrated, using Znt7 knockdown (Znt7KD) 3T3-L1 adipocytes, that reduction in Znt7 expression blunted activations of the signal transduction pathways that regulated both basal and insulin-stimulated glucose uptake in adipocytes, resulting in low glucose uptake and lipid accumulation. The expression of the signaling mediators critical for the initiation of pre-adipocyte differentiation, including Pparγ and C/Ebpα, appeared not to be affected by Znt7KD in 3T3-L1 adipocytes. These findings strongly suggest a role for ZnT7 in adipocyte lipogenesis.

Zinc: The Metal of Life

The importance of zinc was 1st reported for Aspergillus niger. It took over 75 y to realize that zinc is also an essential trace element for rats, and an additional 30 y went by before it was recognized that this was also true for humans. The adult body contains about 2 to 3 g of zinc. Zinc is found in organs, tissues, bones, fluids, and cells. It is essential for many physiological functions and plays a significant role in a number of enzyme actions in the living systems. Bioinformatics estimates report that 10% of the human proteome contains zinc-binding sites. Based on its role in such a plethora of cellular components, zinc has diverse biological functions from enzymatic catalysis to playing a crucial role in cellular neuronal systems. Thus, based on the various published studies and reports, it is pertinent to state that zinc is one of the most important essential trace metals in human nutrition and lifestyle. Its deficiency may severely affect the homeostasis of a biological system. This review compiles the role of zinc in prophylaxis/therapeutics and provides current information about its effect on living beings.

Is serum zinc level associated with prediabetes and diabetes?: a cross-sectional study from Bangladesh

AIMS

To determine serum zinc level and other relevant biological markers in normal, prediabetic and diabetic individuals and their association with Homeostasis Model Assessment (HOMA) parameters.

METHODS

This cross-sectional study was conducted between March and December 2009. Any patient aged ≥ 30 years attending the medicine outpatient department of a medical university hospital in Dhaka, Bangladesh and who had a blood glucose level ordered by a physician was eligible to participate.

RESULTS

A total of 280 participants were analysed. On fasting blood sugar results, 51% were normal, 13% had prediabetes and 36% had diabetes. Mean serum zinc level was lowest in prediabetic compared to normal and diabetic participants (mean differences were approximately 65 ppb/L and 33 ppb/L, respectively). In multiple linear regression, serum zinc level was found to be significantly lower in prediabetes than in those with normoglycemia. Beta cell function was significantly lower in prediabetes than normal participants. Adjusted linear regression for HOMA parameters did not show a statistically significant association between serum zinc level, beta cell function (P = 0.07) and insulin resistance (P = 0.08). Low serum zinc accentuated the increase in insulin resistance seen with increasing BMI.

CONCLUSION

Participants with prediabetes have lower zinc levels than controls and zinc is significantly associated with beta cell function and insulin resistance. Further longitudinal population based studies are warranted and controlled trials would be valuable for establishing whether zinc supplementation in prediabetes could be a useful strategy in preventing progression to Type 2 diabetes.

Effects of zinc supplementation on the anthropometric measurements, lipid profiles and fasting blood glucose in the healthy obese adults

Purpose : The aim of this study was to assess the effects of zinc supplementation on anthropometric measures, improving lipid profile biomarkers, and fasting blood glucose level in obese people.

METHODS

This randomized, double- blind clinical trial was carried out on 60 obese participants in the 18-45 age range for one month. The participants were randomly divided into the intervention group, who received 30 mg/d zinc gluconate, and the placebo group who received 30mg/d starch. Anthropometric measurements (body mass index (BMI), weight and waist circumference) were recorded before and at the end of study. Lipid profile biomarkers and fasting blood glucose were determined using enzymatic procedure. Analysis of Covariance (ANCOVA) test was run to compare the post-treatment values of the two groups, and t-test was conducted to compare within group changes.

RESULTS

Serum zinc concentration was increased significantly in intervention group (p=0.024). BMI and body weight was significantly decreased (p=0.030 and p=0.020, respectively). Lipid profile biomarkers and fating blood glucose did not change significantly but triglyceride level was significantly decreased (p=0.006) in the intervention group.

CONCLUSION

The obtained results indicate that zinc supplementation improves BMI, body weight, and triglyceride concentration without considerable effects on lipid profile and glucose level. Zinc can be suggested as a suitable supplementation therapy for obese people, but more studies are needed to verify the results.

Dietary intake and serum and hair concentrations of minerals and their relationship with serum lipids and glucose levels in hypertensive and obese patients with insulin resistance

Inadequate minerals intake, as well as disruption of some metabolic processes in which microelements are cofactors, are suggested to lead to the development of hypertension. The role of minerals in the pathogenesis of hypertension still remains to be explained. In the present study, we sought to determine associations between serum and hair mineral concentrations and serum lipids and glucose levels. Forty obese hypertensive subjects with insulin resistance and 40 healthy volunteers were recruited in the study. Blood pressure, BMI, and insulin resistance were recorded in all subjects. Levels of lipids, glucose, sodium and potassium, iron, copper, zinc, magnesium, and calcium were assessed in serum. Iron, copper, zinc, magnesium, and calcium were assessed in hair. Dietary intake of the analyzed minerals was estimated. We found distinctly higher concentrations of serum iron and serum and hair calcium as well as markedly lower levels of hair zinc in the hypertensive subjects. The study group manifested also significantly lower daily intake of calcium, magnesium, and iron. We observed a relationship between the concentrations of iron, zinc, and copper in serum and hair and high and low range of cholesterol, triglycerides, and glucose serum levels in the studied patients. Moreover, this study demonstrated significant correlation between serum and hair concentrations of selected minerals and their dietary intake and levels of serum lipids and glucose and blood pressure in the study and the control groups. The obtained results seem to indicate the association between lipid and glucose metabolism and iron, copper, zinc, and calcium concentrations in blood and hair of hypertensive and obese patients with insulin resistance.

Zinc deficiency in chronic kidney disease: is there a relationship with adipose tissue and atherosclerosis?

Cardiovascular complications caused by an accelerated atherosclerotic disease consist the major cause of morbidity and mortality in patients with chronic kidney disease (CKD). These patients present multiple atherosclerotic risk factors, considered traditional, as well as nontraditional risk factors such as inflammation and oxidative stress. These complications are also seen in obesity, in which endothelial dysfunction is one of the early stages of atherosclerosis. The impact of trace metal deficiencies on this process is not well studied in patients with CKD and in obese people, although the influence of trace elements depletion, particularly zinc (Zn), may have significant clinical implications. This brief review describes the functions of Zn as well as the respective role of this trace element in atherosclerosis processes, with a particular emphasis on obese patients with chronic kidney disease.

Nutritional deficiencies in morbidly obese patients: a new form of malnutrition? Part B: minerals

Even though in the Western world there is almost no limitation to a wide variety of food supply, nutritional deficiencies can be found in both normal-weight population and in the obese population. In this review, we examine the prevalence and manifestations of various mineral deficiencies in obese patients.

Correlation between birth weight, leptin, zinc and copper levels in maternal and cord blood

Leptin and zinc are involved in the regulation of appetite. Copper is a trace element regulating the functions of several cuproenzymes that are essential for life. To evaluate the relationship between zinc and copper status and the leptin system in humans, we examined whether leptin concentrations in the mother and the newborn correlate with the weight of mother, placenta and newborn. A total of 88 pregnant women at 38-42 weeks' gestation were studied. All infants were categorized as small for gestational age (SGA) (n = 16), average for gestational age (AGA) (n = 59) or large for gestational age (LGA) (n = 13). Leptin, zinc, and copper levels were measured in maternal and cord serum at birth. Maternal BMI and placental weight of the LGA groups were significantly higher than those of the SGA and AGA groups. Cord and maternal leptin levels of the SGA groups were significantly lower than those of the AGA and LGA groups. Maternal serum leptin levels were positively correlated with BMI and maternal zinc levels in all groups. Cord serum leptin levels of all groups were positively correlated with birth weight and placental weight. Birth weight was negatively correlated with maternal and cord copper level of all groups. Umbilical leptin concentrations of SGA newborns correlated with leptin concentrations of their mothers. In all pregnancies, birth weight increases in association with increase in cord leptin level. Our results suggest that maternal zinc but not copper level has an effect on maternal serum leptin levels. The increase in copper level in both maternal and cord blood may contribute to restriction in fetal growth.

Fructose consumption and moderate zinc deficiency influence growth and adipocyte metabolism in young rats prone to adult-onset obesity

The effects of low zinc, high fructose diet on growth and adipocyte metabolism were examined in rats. At 28 days of age, animals were assigned to diets either adequate in zinc (30 ppm) with water (AZW) or fructose solution (AZF), or low in zinc (5 ppm) with water (LZW) or fructose solution (LZF). Body weight and food and fructose solution intake were measured three times a week. Blood samples were collected at baseline, 4 weeks, and 8 weeks, and energy expenditure was measured. The rats were killed at 12 weeks. Adipocytes were cultured in medium containing C14-glucose and physiological insulin concentrations. The animals in the LZF group consumed less energy and gained less weight than the other groups. Serum zinc concentrations were lower in the LZF than the AZF group. Energy expenditure over a 24-h period did not differ between groups; however, the respiratory quotient in the fed state was higher in the groups consuming fructose solution than in those consuming water. The mesenteric adipocytes from the animals in the LZF group utilized more glucose. Thus, the addition of fructose to a LZ diet reduced energy intake and growth and altered adipocyte fuel metabolism in young growing rats.

Zinc-transporter genes in human visceral and subcutaneous adipocytes: lean versus obese

Zinc ions influence adipose tissue metabolism by regulating leptin secretion and by promoting free fatty acid release and glucose uptake. The mechanisms controlling zinc metabolism in adipose tissue are unknown. We therefore examined the gene-expression levels of a number of zinc-transporting proteins in adipose tissue, comparing subcutaneous fat with visceral fat from lean and obese humans. Both ZnT-proteins responsible for zinc transport from cytosol to extracellular compartments and intracellular vesicles and Zip-proteins responsible for zinc transport to the cytoplasm were expressed in all samples. This suggests that zinc metabolism in adipocytes is actively controlled by zinc-transporters. The expression levels were different in lean and obese subjects suggesting a role for these proteins in obesity. Furthermore, the expression levels were different from subcutaneous fat to intra-abdominal fat suggesting that the metabolic activity in adipocytes is to some extent dependent upon zinc and the activity of zinc-transporting proteins or vice versa.

Hair trace element contents in women with obesity and type 2 diabetes

During 2003-2006 totally 1470 women 46-60 y.o., living mainly in Moscow city and Moscow region, were observed. There were three groups of women: obese, diabetic and practically healthy. The anthropometric and clinical data were compared with elemental status, estimated by atomic emission and mass spectroscopy with inductively coupled plasma (ICP-AES/ICP-MS) analyses of occipital scalp hair. The obesity in women was corresponding to elevated hair K, Hg, Pb and decreased Ca, Mg, Zn, I. The type 2 diabetes was corresponding to elevated hair K, Na, Hg and decreased Ca, Mg, Zn, Co. So, the obtained data demonstrate the very similar changes in hair elemental content in both obese and diabetic women, thus suggesting the general pathophysiological mechanisms of metabolic mineral disturbances.

Effects of dietary phytase on body weight gain, body composition and bone strength in growing rats fed a low-zinc diet

Phytic acid, a major phosphorous storage compound found in foodstuffs, is known to form insoluble complexes with nutritionally essential minerals, including zinc (Zn). Phytases are enzymes that catalyze the removal of these minerals from phytic acid, improving their bioavailability. The objective of the present study was to determine the ability of dietary phytase to affect body weight, body composition, and bone strength in growing rats fed a high phytic acid, low Zn diet. Rats (n = 20) were fed either a control (AIN-93) or phytase supplemented (Natuphos, BASF, 1,500 phytase units (FTU)/kg) diet for a period of 8 weeks. Phytase supplementation resulted in increased (P<.05) bone and plasma Zn, but no change in plasma inorganic phosphorous or bone levels of Ca, Fe, or Mg. The addition of phytase to the diets resulted in a 22.4% increase (P<.05) in body weight at the end of the study as compared with rats fed a control diet. Dual x-ray absorptiometry (DXA) revealed that phytase supplementation resulted in increase lean body mass (LBM, P<.001) and increased bone mineral content (BMC, P<.001) as compared with feeding the control diet. Bone studies indicated that femurs and tibias from phytase supplemented rats had greater mass (P<.05) and were stronger (P<.05) than rats fed the control diet. This data suggest that the addition of phytase to low Zn diets results in improved Zn status, which may be responsible for beneficial effects on growth, body composition, and bone strength.

[Role of zinc in insulin resistance]

This review reports the etiological aspects of insulin resistance as well as the participation of zinc in this process. Zinc participates in the metabolic pathways involving protein synthesis, and the metabolism of carbohydrate, lipid and nucleic acid. This element has been associated with the interaction between hormones and their receptors and to the improvement in the post-receptor stimulus. In vitro studies show that insulin may form a complex with zinc improving the solubility of this hormone in the pancreatic beta cells and also increasing the binding ability of insulin to its receptor. Regarding obesity and insulin resistance, alterations in zinc concentration and distribution in tissues, as well as improvement in sensitivity to insulin after supplementation with this element, have been detected. Thus, the metabolic role of zinc in the insulin resistance syndrome should be further investigated having in mind that this element may contribute to the control of the usual metabolic alterations present in obese patients.

Increased oxidative stress and hypozincemia in male obesity

OBJECTIVES

Antioxidants protect an organism from the detrimental effects of free radicals via scavenging or inhibiting their formation. Alterations in the levels of antioxidants and several essential trace elements in the plasma and various tissues of ob/ob mice have been reported previously. The aim of this study was to investigate oxidative status and trace elements in obese individuals.

DESIGN AND METHODS

Seventy-six obese men (body mass index (BMI) > 30 kg/m(2)) and 24 healthy, age-matched male control volunteers were enrolled in the study. Fasting plasma insulin, glucose, triglyceride (TG), total cholesterol, VLDL, and HDL levels, erythrocyte glutathione peroxidase (GSH-Px) and copper zinc-superoxide dismutase (CuZn-SOD) activities, and erythrocyte thiobarbituric acid reactive substances (TBARS) levels were measured in both groups. Erythrocyte copper (Cu), zinc (Zn) and iron (Fe) levels were also measured.

RESULTS

We found that the mean Cu and Fe levels in obese individuals were not significantly different than those in the control group, whereas the mean Zn levels were significantly lower than those of the control group (p = 0.023). The mean erythrocyte CuZn-SOD and GSH-Px levels in obese individuals were significantly lower than those in controls (p = 0.001) whereas erythrocyte TBARS levels were significantly higher (p = 0.001) than those of the control group.

CONCLUSION

We conclude that male obesity is associated with defective antioxidant status and hypozincemia, which may have implications in the development of obesity related health problems.

Zinc-induced hyperleptinemia relates to the amelioration of sucrose-induced obesity with zinc repletion

OBJECTIVE

Dietary zinc repletion can ameliorate sucrose-induced obesity. A positive correlation between zinc and leptin has been recently noted, and both are known as important mediators in appetite control. In this study, we examined whether the reported amelioration of sucrose-induced obesity by zinc repletion was consequent on the changes in circulating leptin levels.

RESEARCH METHODS AND PROCEDURES

Mice with obesity that was induced by giving a 32% sucrose solution in addition to a semipurified diet were divided into two groups based on whether they had 20 mg/liter zinc supplementation in their drinking water.

RESULTS

As expected, the mice with sucrose-induced obesity had hyperglycemia, hyperinsulinemia, hypertriglyceridemia, hyperleptinemia, and hypozincemia when compared with the mice given the diet alone. Body weight gain, body fat content, and food and sucrose intake tended to decrease but not with statistical significance in sucrose-fed obese mice with zinc supplementation. Nevertheless, some serum variables (glucose, insulin, triglycerides, and zinc) in sucrose-fed obese mice with zinc treatment were approximate to those values of the mice given the diet alone. Moreover, sucrose-fed obese mice with zinc supplementation had the highest serum values of leptin.

DISCUSSION

This study indicates that the amelioration of sucrose-induced obesity by zinc repletion may be partly attributable to the hyperleptinemia induced by the mineral.

Zinc may be a mediator of leptin production in humans

Obese individuals have hyperleptinemia and hypozincemia. Moreover, leptin and zinc have circadian changes in circulating concentrations. We investigated their possible interaction and examined whether a difference existed between obese men and their lean controls. The results indicated the pattern of circadian change in plasma zinc and leptin did not markedly differ between the obese subjects and the lean controls. However, the obese had higher leptin and lower zinc plasma values at each sampling time than did the lean controls. Because an inverse correlation was found in plasma values between zinc and leptin (r=-0.51, p=0.012), we further determined the role zinc might play in leptin production by human subcutaneous adipose tissue from female donors. The in vitro study showed that zinc treatment (0.2 mmol/L) significantly increased leptin production (142%), however, this increment did not surpass that by insulin (10 nmol/L). The data of this study suggest an interactive connection between zinc and leptin.

Zinc coadministration attenuates melatonin's effect on nitric oxide production in mice

Both melatonin (MEL) and zinc (Zn) are considered beneficial for anti-immunosenescence. MEL's effects on immune functions are partly attributed to an interaction with Zn. However, the augmentation of or interference with MEL's effects by coadministration of Zn remains unclear. In this study, adult older mice received either MEL (10 microg/mL), Zn (22 microg/mL), MEL+Zn, or null supplementation from drinking water for 3 mo. The results showed that treated mice, irrespective of the type of added chemicals, had higher body-weight gain and body-fat content than control mice. MEL- and Zn-treated mice also had increased serum free fatty acid levels. In addition, the MEL group had decreased serum NOx (nitrite+nitrate) values. Serum tumor necrosis factor-alpha levels were increased, although nonsignificantly, in mice that received either MEL or Zn supplementation. However, the differences described were not retained in the mice that received MEL+Zn treatment. We conclude that a high-dose Zn coadministration might exert negative influences on MEL's regulatory effects, at least on nitric oxide production.