Effect of high-dose zinc supplementation with oral hypoglycemic agents on glycemic control and inflammation in type-2 diabetic nephropathy patients

Plasma metals, genetic risk, and rapid kidney function decline among type 2 diabetes

BACKGROUND

Rapid kidney function decline (RKFD) is a main clinical feature of early chronic kidney disease (CKD) in type 2 diabetes (T2D). Environmental and genetic factors influencing RKFD remain inadequately elucidated.

OBJECTIVES

This study aimed to examine the associations of metals with RKFD among T2D and to further investigate the effect of metal mixtures on RKFD with the modifying effect of genetic susceptibility.

METHODS

This study included 2209 people with T2D (1942 had genotyping data) free of CKD at baseline from the Dongfeng-Tongji cohort. We used inductively coupled plasma-mass spectrometry (ICP-MS) to measure 23 metals in baseline plasma. Using elastic net (ENET), multivariate logistic regression, and Bayesian kernel machine regression (BKMR) model, we examined independent associations of multiple metals with RKFD. We calculated the environmental risk score (ERS) to assess the effects of metal mixtures on RKFD and the genetic risk score (GRS) to assess genetic susceptibility. RKFD was defined as estimated glomerular filtration rate (eGFR) loss > 3 mL/min/1.73 m2/year.

RESULTS

During a median of 9.8 years follow-up, 262 participants developed RKFD. Aluminum, vanadium, zinc, selenium, rubidium, tin, barium, and tungsten were screened from ENET. In multivariate logistic models, vanadium, selenium, and tungsten were negatively associated with RKFD, while zinc, tin, and rubidium were positively associated. The BKMR showed a nonlinear association of vanadium and rubidium with RKFD and interactions between metals (barium‑vanadium, barium‑rubidium). The ERS was positive associated with RKFD (per SD increase in ERS, OR = 1.94, 95% CI: 1.66, 2.27). No significant interaction between ERS and GRS was observed on RKFD, however, participants in the highest ERS and GRS group had the highest RKFD risk.

CONCLUSION

Vanadium and rubidium were associated with RKFD in T2D. Metal mixtures was associated with an increased risk of RKFD in T2D, particularly in those at high genetic risk.

Zinc and Diabetes: A Connection between Micronutrient and Metabolism

Diabetes mellitus is a global health problem and a major contributor to mortality and morbidity. The management of this condition typically involves using oral antidiabetic medication, insulin, and appropriate dietary modifications, with a focus on macronutrient intake. However, several human studies have indicated that a deficiency in micronutrients, such as zinc, can be associated with insulin resistance as well as greater glucose intolerance. Zinc serves as a chemical messenger, acts as a cofactor to increase enzyme activity, and is involved in insulin formation, release, and storage. These diverse functions make zinc an important trace element for the regulation of blood glucose levels. Adequate zinc levels have also been shown to reduce the risk of developing diabetic complications. This review article explains the role of zinc in glucose metabolism and the effects of its inadequacy on the development, progression, and complications of diabetes mellitus. Furthermore, it describes the impact of zinc supplementation on preventing diabetes mellitus. The available information suggests that zinc has beneficial effects on the management of diabetic patients. Although additional large-scale randomized clinical trials are needed to establish zinc's clinical utility further, efforts should be made to increase awareness of its potential benefits on human health and disease.

Effects of Zinc Supplementation on Inflammatory Status and Nonalcoholic Steatohepatitis in Overweight or Obese Children: a Randomized Clinical Trial

The purpose of the present clinical trial was to determine the impact of zinc supplementation on serum liver enzymes, steatosis severity, lipid profile, and inflammatory status in overweight or obese children with nonalcoholic steatohepatitis (NASH). This randomized controlled trial was conducted by enrolling 60 children with NASH, aged 10-18 years old. The participants were randomly assigned to two groups that received either 30 mg/day of elemental zinc or placebo for 16 weeks. The severity of liver steatosis was evaluated using liver ultrasonography. Fasting blood samples were collected from each patient at the beginning and after 16 weeks of intervention to measure biochemical parameters. Following a 16-week intervention, zinc supplementation compared with placebo significantly decreased serum alanine aminotransferase (ALT) concentrations and high-sensitivity C-reactive protein and considerably enhanced HDL-cholesterol values. However, zinc intake had no considerable impact on aspartate aminotransferase, the severity of liver steatosis, anthropometric parameters, and other lipid indices versus the placebo group. Overall, zinc supplementation showed a promising impact on serum ALT, HDL-cholesterol, and inflammatory status in overweight or obese children suffering from NASH. Zinc supplementation may be a new strategy for the amelioration of NASH in overweight or obese children. This trial has been registered on the Iranian website for registration of clinical trials with the special ID of IRCT20200531047614N1 ( https://www.irct.ir/trial/48543 ).

Zinc Supplementation in Individuals with Prediabetes and type 2 Diabetes: a GRADE-Assessed Systematic Review and Dose-Response Meta-analysis

Zinc supplementation has therapeutic effects on cardiovascular disease (CVD) risk factors, including dyslipidemia, hyperglycemia, and inflammation as the main contributors to CVD pathogenesis. Since CVD is a major cause of mortality among people with type 2 diabetes mellitus (T2DM), this study aimed to overview the potential effects of zinc supplementation on CVD risk factors in T2DM patients. To determine appropriate randomized clinical trials (RCTs) investigating the effects of zinc supplementation on CVD risk factors, electronic sources including PubMed, Web of Science, and Scopus were systematically searched until January 2023. The heterogeneity of trials was checked using the I2 statistic. According to the heterogeneity tests, random-effects models were estimated, and pooled data were defined as the weighted mean difference (WMD) with a 95% confidence interval (CI). Of the 4004 initial records, 23 studies that met inclusion criteria were analyzed in this meta-analysis. The pooled findings indicated the significant lowering effects of zinc supplementation on triglycerides (TG), total cholesterol (TC), fasting blood glucose (FBG), hemoglobin A1C (HbA1C), and C-reactive protein (CRP), while high-density cholesterol (HDL) concentrations showed an elevation after zinc supplementation. In addition to statistical significance, the effect of zinc supplementation on most of the variables was clinically significant; however, the quality of evidence in the included studies is regarded as low or very low for most variables. Our study demonstrated that zinc supplementation has beneficial effects on glycemic control markers, lipid profile, and CRP levels as a classic marker of inflammation in T2DM. Due to the high degree of heterogeneity between studies and the low rate of quality in them, further well-designed studies are necessitated to strengthen our findings.

Effect of Zinc Supplementation on Lipid Profile and Body Composition in Patients with Type 2 Diabetes Mellitus: A GRADE-Assessed Systematic Review and Dose-Response Meta-analysis

The aim of this systematic review and meta-analysis of randomized controlled trials (RCTs) is to investigate the overall effects of zinc supplementation on lipid profile and body composition such as body weight (BW), body mass index (BMI), triglycerides (TG), total cholesterol (TC), low-density lipoprotein-cholesterol (LDL-C), and high-density lipoprotein-cholesterol (HDL-C) in patients with type 2 diabetes mellitus (T2DM). Scopus, Web of Science, PubMed, and Embase databases were searched from inception through October, 2023. The I2 and Cochran's Q tests were used to assess heterogeneity between studies. Nineteen RCTs (n = 1357 participants) were included in the meta-analysis. Zinc supplementation significantly reduced TG (WMD = - 17.41 mg/dL; 95% CI: - 22.60, - 12.22; P < 0.001), TC (WMD: - 19.60 mg/dL; 95% CI: - 28.46, - 10.73, P < 0.001), LDL-C (WMD = - 8.80 mg/dL; 95% CI: - 14.80, - 2.81; P = 0.004), and BMI (WMD = - 0.53 kg/m2; 95% CI: - 1.05, - 0.01; P = 0.046) but not BW (WMD: - 0.51 kg, 95 % CI: - 1.99, 0.97, P = 0.498). Moreover, zinc supplementation increased HDL-C (WMD = 4.82 mg/dL; 95% CI: 0.88, 8.76; P = 0.016) in patients with T2DM. Our results propose that zinc supplementation may be an effective strategy for improving lipid profile and body composition in patients with T2DM.

Update on the ZNT8 epitope and its role in the pathogenesis of type 1 diabetes

Type 1 diabetes (T1D) is an organ-specific chronic autoimmune disease mediated by autoreactive T cells. ZnT8 is a pancreatic islet-specific zinc transporter that is mainly located in β cells. It not only participates in the synthesis, storage and secretion of insulin but also maintains the structural integrity of insulin. ZnT8 is the main autoantigen recognized by autoreactive CD8+ T cells in children and adults with T1D. This article summarizes the latest research results on the T lymphocyte epitope and B lymphocyte epitope of ZnT8 in the current literature. The structure and expression of ZnT8, the role of ZnT8 in insulin synthesis and its role in autoimmunity are reviewed. ZnT8 is the primary autoantigen of T1D and is specifically expressed in pancreatic islets. Thus, it is one of biomarkers for the diagnosis of T1D. It has broad prospects for further research on immunomodulators for the treatment of T1D.

Antioxidants for adults with chronic kidney disease

BACKGROUND

Chronic kidney disease (CKD) is a significant risk factor for cardiovascular disease (CVD) and death. Increased oxidative stress in people with CKD has been implicated as a potential causative factor. Antioxidant therapy decreases oxidative stress and may consequently reduce cardiovascular morbidity and death in people with CKD. This is an update of a Cochrane review first published in 2012.

OBJECTIVES

To examine the benefits and harms of antioxidant therapy on death and cardiovascular and kidney endpoints in adults with CKD stages 3 to 5, patients undergoing dialysis, and kidney transplant recipients.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies until 15 November 2022 using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Registry Platform (ICTRP) Search Portal, and ClinicalTrials.gov.

SELECTION CRITERIA

We included all randomised controlled trials investigating the use of antioxidants, compared with placebo, usual or standard care, no treatment, or other antioxidants, for adults with CKD on cardiovascular and kidney endpoints.

DATA COLLECTION AND ANALYSIS

Titles and abstracts were screened independently by two authors who also performed data extraction using standardised forms. Results were pooled using random effects models and expressed as risk ratios (RR) or mean difference (MD) with 95% confidence intervals (CI). Confidence in the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

MAIN RESULTS

We included 95 studies (10,468 randomised patients) that evaluated antioxidant therapy in adults with non-dialysis-dependent CKD (31 studies, 5342 patients), dialysis-dependent CKD (41 studies, 3444 patients) and kidney transplant recipients (21 studies, 1529 patients). Two studies enrolled dialysis and non-dialysis patients (153 patients). Twenty-one studies assessed the effects of vitamin antioxidants, and 74 assessed the effects of non-vitamin antioxidants. Overall, the quality of included studies was moderate to low or very low due to unclear or high risk of bias for randomisation, allocation concealment, blinding, and loss to follow-up. Compared with placebo, usual care, or no treatment, antioxidant therapy may have little or no effect on cardiovascular death (8 studies, 3813 patients: RR 0.94, 95% CI 0.64 to 1.40; I² = 33%; low certainty of evidence) and probably has little to no effect on death (any cause) (45 studies, 7530 patients: RR 0.95, 95% CI 0.82 to 1.11; I² = 0%; moderate certainty of evidence), CVD (16 studies, 4768 patients: RR 0.79, 95% CI 0.63 to 0.99; I² = 23%; moderate certainty of evidence), or loss of kidney transplant (graft loss) (11 studies, 1053 patients: RR 0.88, 95% CI 0.67 to 1.17; I² = 0%; moderate certainty of evidence). Compared with placebo, usual care, or no treatment, antioxidants had little to no effect on the slope of urinary albumin/creatinine ratio (change in UACR) (7 studies, 1286 patients: MD -0.04 mg/mmol, 95% CI -0.55 to 0.47; I² = 37%; very low certainty of evidence) but the evidence is very uncertain. Antioxidants probably reduced the progression to kidney failure (10 studies, 3201 patients: RR 0.65, 95% CI 0.41 to 1.02; I² = 41%; moderate certainty of evidence), may improve the slope of estimated glomerular filtration rate (change in eGFR) (28 studies, 4128 patients: MD 3.65 mL/min/1.73 m², 95% CI 2.81 to 4.50; I² = 99%; low certainty of evidence), but had uncertain effects on the slope of serum creatinine (change in SCr) (16 studies, 3180 patients: MD -13.35 µmol/L, 95% CI -23.49 to -3.23; I² = 98%; very low certainty of evidence). Possible safety concerns are an observed increase in the risk of infection (14 studies, 3697 patients: RR 1.30, 95% CI 1.14 to 1.50; I² = 3%; moderate certainty of evidence) and heart failure (6 studies, 3733 patients: RR 1.40, 95% CI 1.11 to 1.75; I² = 0; moderate certainty of evidence) among antioxidant users. Results of studies with a low risk of bias or longer follow-ups generally were comparable to the main analyses.

AUTHORS' CONCLUSIONS

We found no evidence that antioxidants reduced death or improved kidney transplant outcomes or proteinuria in patients with CKD. Antioxidants likely reduce cardiovascular events and progression to kidney failure and may improve kidney function. Possible concerns are an increased risk of infections and heart failure among antioxidant users. However, most studies were of suboptimal quality and had limited follow-up, and few included people undergoing dialysis or kidney transplant recipients. Furthermore, the large heterogeneity in interventions hampers drawing conclusions on the efficacy and safety of individual agents.

The Effect of Zinc Supplementation on Lipid Profiles in Patients with Type 2 Diabetes Mellitus: A Systematic Review and Dose-Response Meta-Analysis of Randomized Clinical Trials

Research on the effects of zinc supplementation on lipid profiles in people with type 2 diabetes mellitus (T2DM) has been inconsistent. This systematic review and meta-analysis was performed to summarize the current data on the effects of zinc supplementation on lipid profiles in patients with T2DM. Three online databases including PubMed, Scopus, and Web of Science were searched to find relevant studies published until September 2022. The exposure was zinc supplementation, and the outcomes were low-density lipoprotein (LDL), high-density lipoprotein (HDL), triglyceride (TG), and total cholesterol (TC). Fourteen randomized clinical trials consisting of 1067 patients were included in the statistical analysis. Significant improvement was observed in all 4 lipid profile components. Following zinc supplementation, a significant decrease was observed in TC (weighted mean difference [WMD]: -16.16; 95% confidence interval [CI]: -26.43, -5.89; P = 0.002), LDL (WMD: -6.18; 95% CI: -9.35, -3.02; P < 0.001), and TG (WMD: -13.08; 95% CI: -21.83, -4.34; P = 0.003). After analyzing 13 studies reporting HDL, a significant increase was seen (WMD: 3.76; 95% CI: 1.30, 6.22; P = 0.003). In a nonlinear dose-response analysis, a significant inverse association was observed between <12 wk zinc supplementation and TC, LDL, and TG (TC: WMD: -5, Pnonlinearity < 0.001; LDL: WMD: -5, Pnonlinearity = 0.07, TG: WMD: -16.5, Pnonlinearity = 0.006). Nonlinear dose-response analysis shows that the optimum elemental zinc dosage for the best response to the supplementation for TC, LDL, and TG are 120, 100, and 140 mg/d, respectively (TC: WMD: -5, Pnonlinearity < 0.001; LDL: WMD: -10, Pnonlinearity = 0.006, TG: WMD: -50, Pnonlinearity = 0.031). In conclusion, we found significant changes in all 4 components of the lipid profile through zinc supplementation in T2DM patients. Based on our findings, zinc supplementation may have profound favorable consequences on the lipid profile of T2DM patients, especially in the zinc-deficient group.

Effect of zinc supplementation on blood sugar control in the overweight and obese population: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Although overweight and obese people have a higher risk of type 2 diabetes incidence than normal-weight individuals, the efficacy of zinc supplementation in blood sugar control in overweight and obese people remained unknown. This meta-analysis attempted to address this issue.

METHODS

Databases including PubMed, Embase, and the Cochrane Library were searched from inception until May 2022 to identify randomized controlled trials (RCTs) investigating the effects of zinc supplementation among participants who were overweight or obese without language restriction. It is a random-effect meta-analysis that analyzed the impact of zinc supplementation on fasting glucose (FG) (i.e., primary outcome) and other variables including fasting insulin (FI), homeostasis model assessment-insulin resistance index (HOMA-IR), glycated hemoglobin (HbA1c), high-sensitivity C-reactive protein (hs-CRP), and 2-hour postprandial glucose (2 h- PG).

RESULTS

Analysis of 12 eligible RCTs involving 651 overweight/obese participants demonstrated that zinc supplementation significantly improves FG (weighted mean difference [WMD]: -8.57 mg/dL; 95% confidence interval [CI]: -14.04 to -3.09 mg/dL, p = 0.002), HOMA-IR (WMD: -0.54; 95% CI: -0.78 to -0.30, p < 0.001), HbA1c (WMD: -0.25%; 95% CI: -0.43% to -0.07%, p = 0.006), and 2 h-PG (WMD: -18.42 mg/dL; 95% CI: -25.04 to -11.79 mg/dL, p < 0.001) compared to those in the control group. After conducting subgroup analyses, we found that the primary outcome, FG, showed more significant results in the subgroups with Asia, Zinc supplementation alone, higher dose (≥30 mg) and patients with diabetes.

CONCLUSION

Our meta-analysis indicated that zinc supplementation benefits blood sugar control in overweight and obese populations, with an especially significant reduction in FG.

Zinc supplementation and cardiovascular disease risk factors: A GRADE-assessed systematic review and dose-response meta-analysis

BACKGROUND AND OBJECTIVE

A deficit in zinc has been related to a higher probability of developing cardiovascular diseases (CVDs). The anti-inflammatory and anti-oxidative capabilities of zinc may have a wide range of therapeutic impacts on CVDs. We conducted a comprehensive systematic review and meta-analysis of the possible impacts that zinc supplementation may have on the risk factors associated with CVDs.

METHODS

To identify eligible randomized clinical trials (RCTs) evaluating the effects of zinc supplementation on CVDs risk factors, electronic databases including PubMed, Web of Science, and Scopus were systematically searched up to January 2023. The heterogeneity of trials was checked using the I² statistic. According to the heterogeneity tests, random effects models were estimated and pooled data were defined as the weighted mean difference (WMD) with a 95% confidence interval (CI).

RESULTS

Of 23165 initial records, 75 studies that met inclusion criteria were analyzed in this meta-analysis. The pooled findings indicated the significant lowering effects of zinc supplementation on triglycerides (TG), total cholesterol (TC), fasting blood glucose (FBG), Hemoglobin A1C (HbA1C), Homeostatic Model Assessment for Insulin Resistance (HOMA-IR), C-reactive protein (CRP), interleukin-6 (IL-6), Tumor necrosis factor-α (TNF-α), nitric oxide (NO), malondialdehyde (MDA), total antioxidant capacity (TAC), and glutathione (GSH), with no noticeable effects on low-density lipoprotein (LDL), high-density lipoprotein (HDL), insulin, systolic blood pressure (SBP), diastolic blood pressure (DBP), aspartate transaminase (AST), and Alanine aminotransferase (ALT).

CONCLUSION

Overall, zinc supplementation may boost recognized coronary risk factors that contribute to the development of CVDs. Future research should be conducted to bolster our results.

Effect of zinc supplementation in the management of type 2 diabetes: A grading of recommendations assessment, development, and evaluation-assessed, dose-response meta-analysis of randomized controlled trials

The question of whether zinc supplementation may improve cardio-metabolic health in patients with type 2 diabetes mellitus (T2DM) remains controversial and require further evaluation. This study aimed to summarize the effectiveness of oral zinc supplementation in improving cardio-metabolic risk markers in people with T2DM. We searched PubMed, Scopus, and Web of Science from inception to April 2023, for randomized controlled trials (RCTs). RCTs of type 2 diabetic adults (aged ≥18 years) comparing zinc supplementation with placebo were included. We excluded studies if not randomized, involved co-supplementation, and were conducted in children or pregnant women. Glycemic indices, lipid profiles, blood pressure, anthropometric measure, c-reactive protein (CRP), creatinine, and serum zinc were extracted. Certainty of evidence was assessed using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) methods. We used a random-effect model to perform the dose-response analysis. Effect sizes were presented as mean difference (MD) and 95% confidence interval (CI). 22 studies (n = 1442 participants) were included. The certainty of the evidence was rated as moderate to high. Zinc supplementation significantly reduced glycemic indices: including two-hour postprandial glucose (2hpp) (mean difference (MD): -34.34 mg/dl; 95%CI: -51.61∼ -17.07), fast blood sugar (FBS) (MD: -23.32 mg/dl; 95% CI: -33.81∼ -12.83), and hemoglobin A1c (HbA1c) (MD: -0.47; 95% CI: -0.71∼ -0.23). Zinc had a favorable effect on lipid profiles low-density lipoprotein (LDL) (MD: -10.76 mg/dl; CI: -17.79∼-3.73), triglyceride (TG) (MD: -18.23 mg/dl; CI: -32.81∼-3.65), total cholesterol (TC) (MD: -12.74 mg/dl; CI: -21.68∼-3.80), VLDL (MD: -5.39 mg/dl; CI: -7.35∼-3.43) and high-density lipoprotein (HDL) (MD: 4.04 mg/dl; CI: 0.96 ∼ 7.12). Systolic blood pressure (SBP) (MD): -3.64 mmHg; 95% CI: -6.77∼ -0.52), weight (MD: 1.00 kg; 95% CI: 0.34∼1.66), CRP (MD: -3.37 mg/l, 95% CI: -4.05∼ -2.70), and serum zinc (MD: 15.38 µg/dl; 95% CI: 10.74∼ 20.02) changed to a statistically significant extent with zinc supplementation. There was also a linear association between additional 10 mg/d zinc treatment with FBS, HbA1c, HDL, LDL, TG, TC, and serum zinc. A non-linear dose-response gradient was seen for FBS, HDL, and SBP (p < 0.05). Egger's test showed no substantial publication bias. Our findings strongly suggest a potential beneficial effect of zinc supplementation on type 2 diabetic patients. Further high-quality research is needed to determine the optimal form, dosage, and duration of zinc supplementation for this population.

Capsaicin and Zinc Signalling Pathways as Promising Targets for Managing Insulin Resistance and Type 2 Diabetes

The global burden of type 2 diabetes (T2DM) has led to significant interest in finding novel and effective therapeutic targets for this chronic disorder. Bioactive food components have effectively improved abnormal glucose metabolism associated with this disease. Capsaicin and zinc are food components that have shown the potential to improve glucose metabolism by activating signalling events in the target cells. Capsaicin and zinc stimulate glucose uptake through the activation of distinct pathways (AMPK and AKT, respectively); however, calcium signal transduction seems to be the common pathway between the two. The investigation of molecular pathways that are activated by capsaicin and zinc has the potential to lead to the discovery of new therapeutic targets for T2DM. Therefore, this literature review aims to provide a summary of the main signalling pathways triggered by capsaicin and zinc in glucose metabolism.

NADPH oxidase inhibitor development for diabetic nephropathy through water tank model

Oxidative stress can cause generation of uncontrolled reactive oxygen species (ROS) and lead to cytotoxic damage to cells and tissues. Recently, it has been shown that transient ROS generation can serve as a secondary messenger in receptor-mediated cell signaling. Although excessive levels of ROS are harmful, moderated levels of ROS are essential for normal physiological function. Therefore, regulating cellular ROS levels should be an important concept for development of novel therapeutics for treating diseases. The overexpression and hyperactivation of NADPH oxidase (Nox) can induce high levels of ROS, which are strongly associated with diabetic nephropathy. This review discusses the theoretical basis for development of the Nox inhibitor as a regulator of ROS homeostasis to provide emerging therapeutic opportunities for diabetic nephropathy.

Triangulating evidence for the causal impact of single-intervention zinc supplement on glycaemic control for type 2 diabetes: systematic review and meta-analysis of randomised controlled trial and two-sample Mendelian randomisation

Although previous studies suggested the protective effect of Zn for type 2 diabetes (T2D), the unitary causal effect remains inconclusive. We investigated the causal effect of Zn as a single intervention on glycaemic control for T2D, using a systematic review of randomised controlled trials and two-sample Mendelian randomisation (MR). Four primary outcomes were identified: fasting blood glucose/fasting glucose, HbA1c, homeostatic model assessment for insulin resistance (HOMA-IR) and serum insulin/fasting insulin level. In the systematic review, four databases were searched until June 2021. Studies, in which participants had T2D and intervention did not comprise another co-supplement, were included. Results were synthesised through the random-effects meta-analysis. In the two-sample MR, we used single-nucleotide polymorphisms (SNP) from MR-base, strongly related to Zn supplements, to infer the relationship causally, but not specified T2D. In the systematic review and meta-analysis, fourteen trials were included with overall 897 participants initially. The Zn supplement led to a significant reduction in the post-trial mean of fasting blood glucose (mean difference (MD): −26·52 mg/dl, 95 % CI (−35·13, −17·91)), HbA1c (MD: −0·52 %, 95 % CI: (−0·90, −0·13)) and HOMA-IR (MD: −1·65, 95 % CI (−2·62, −0·68)), compared to the control group. In the two-sample MR, Zn supplement with two SNP reduced the fasting glucose (inverse-variance weighted coefficient: −2·04 mmol/l, 95 % CI (−3·26, −0·83)). From the two methods, Zn supplementation alone may causally improve glycaemic control among T2D patients. The findings are limited by power from the small number of studies and SNP included in the systematic review and two-sample MR analysis, respectively.

The impact of zinc on the molecular signaling pathways in the diabetes disease

Since there's been an upsurge in people with diabetes or pre-diabetes conditions, many studies have been conducted to evaluate approaches for reducing the complications of diabetes. One of the most common therapeutic elements suggested for this purpose is zinc (Zn). Zn has long been shown to positively improve complications of both type 1 and type 2 diabetes. This review aims to provide comprehensive information about the influence of Zn on the various signaling pathways in multiple tissues with diabetic conditions, with great attention to the treatment period and effective dose of Zn.

Prospective association between baseline plasma zinc concentration and development of proteinuria in Chinese hypertensive patients

OBJECTIVE

We aimed to evaluate the association between baseline plasma zinc and the development of proteinuria as well as possible effect modifiers in hypertensive patients.

METHODS

This is a subset of the China Stroke Primary Prevention Trial (CSPPT) Renal Sub-Study. In the CSPPT, participants were randomized to receive a daily oral dose of 1 tablet containing 10 mg enalapril and 0.8 mg folic acid or 1 tablet containing 10 mg enalapril only. A total of 783 participants with plasma zinc measurements and without proteinuria at baseline were included in the current study. The study outcome was the development of proteinuria during the follow-up, defined as a urine dipstick reading of trace or ≥1+ at the exit visit.

RESULTS

During a median follow-up duration of 4.4 years, the development of proteinuria occurred in 93 (11.9 %) participants. There was an inverse relation of baseline plasma zinc with the development of proteinuria (per SD increment; OR, 0.74, 95 % CI: 0.55-0.99), p for trend of quartiles = 0.005.

CONCLUSIONS

In Chinese hypertensive patients, there was a significant inverse association between baseline plasma zinc and the development of proteinuria, although plasma zinc remained in the reference range.

Diabetic kidney disease in type 2 diabetes: a review of pathogenic mechanisms, patient-related factors and therapeutic options

The global prevalence of diabetic kidney disease is rapidly accelerating due to an increasing number of people living with type 2 diabetes. It has become a significant global problem, increasing human and financial pressures on already overburdened healthcare systems. Interest in diabetic kidney disease has increased over the last decade and progress has been made in determining the pathogenic mechanisms and patient-related factors involved in the development and pathogenesis of this disease. A greater understanding of these factors will catalyse the development of novel treatments and influence current practice. This review summarises the latest evidence for the factors involved in the development and progression of diabetic kidney disease, which will inform better management strategies targeting such factors to improve therapeutic outcomes in patients living with diabetes.

Association of Serum Zinc Concentration with Preservation of Renal Function After Bariatric Surgery: a Retrospective Pilot Study

BACKGROUND

Although serum zinc level (Zn) is known to impact renal function in patients with diabetes, their correlation following bariatric surgery remains unknown. This study aimed at assessing the association of Zn with estimated glomerular filtration rate (eGFR) after laparoscopic sleeve gastrectomy (LSG).

METHODS

One hundred and twenty-nine patients in total (mean age, 38.1 ± 10.8; body mass index, 39.1 ± 5.1 kg/m²) with normal preoperative kidney function undergoing LSG at a single tertiary referral center were reviewed. The primary study endpoint was the relationship between Zn and post-LSG eGFR at 12-month follow-up. The secondary outcomes were the associations of percentage weight loss (%WL) with changes in Zn (△Zn) and eGFR (△eGFR).

RESULTS

The incidence of zinc deficiency was 8.5%, 8.1%, and 29.9% at baseline, post-LSG and one- and 12-month follow-up, respectively. At 12-month follow-up, Zn dropped from 104.1 ± 19.2 to 85.3 ± 38.9 μg/dL (p = 0.001), while eGFR levels decreased from 106.6 ± 10.3 to 102.1 ± 19.4 mL/min per 1.73 m² (p = 0.025). Zn correlated positively with eGFR at 6-month (r = 0.252, p = 0.037) and 12-month (r = 0.41, p = 0.001) follow-ups. Multiple linear regression analyses including baseline variables of age, sex, BMI, %WL, and diabetes identified Zn and %WL as independent predictors of eGFR at 12-month follow-up. There was no evidence of multicollinearity among these variables. Despite positive association between %WL and △eGFR (r = 0.222, p = 0.031), no correlation was noted between %WL and △Zn (r = - 0.129, p = 0.40).

CONCLUSION

The results demonstrated a positive relationship between post-LSG serum zinc levels and preservation of renal function among patients with obesity in a surgical setting. Large-scale studies are warranted to support the findings.

Relationships of the Trace Elements Zinc and Magnesium With Diabetic Nephropathy-Associated Renal Functional Damage in Patients With Type 2 Diabetes Mellitus

Zinc (Zn) and magnesium (Mg) are essential trace elements in humans. Their deficiency may be associated with inflammation and oxidative stress (OS) in patients with diabetic nephropathy (DN), but the mechanisms involved have not been fully characterized. We aimed to investigate the relationships between circulating concentrations of Zn and Mg and pro-inflammatory factors with DN-associated renal functional damage in patients with type 2 diabetes mellitus (T2DM). To this end, we studied 20 healthy people, 24 patients with T2DM, and 59 patients with T2DM and T2DN. Serum and urine Zn and Mg concentrations were measured using the 2-(5-nitro-2-pyridylazo)-5-(N-propyl-N-sulfopropylamine) phenol (nitro-PAPS) chromogenic method and the xylidyl blue method, respectively, and the circulating concentrations of pro-inflammatory cytokines [interleukin (IL)-1β, IL-6, IL-8, IL-10, IL-12, and tumor necrosis factor-α (TNF-α)] were measured using flow cytometry. The serum concentrations of Zn and Mg were significantly lower in patients with T2DM and DN than in healthy controls. Serum Zn, urine Zn, and urine Mg concentrations decreased, while those of IL-6 and IL-8 increased with the progression of DN-associated renal functional damage. Furthermore, the serum and urine Zn concentrations negatively correlated with the serum IL-6 and IL-8 concentrations. Notably, the serum Zn concentration was found to independently protect against DN in patients with T2DM. Hypozincemia may be associated with the T2DN-associated renal functional damage because it exacerbates inflammation.

The Effects of Zinc Supplementation on C-Reactive Protein and Inflammatory Cytokines: A Meta-Analysis and Systematical Review

Zinc is known for anti-inflammatory and antioxidant roles. In this meta-analysis, we aim to evaluate the impact of zinc supplementation on inflammatory markers, acute-phase reactants, and serum zinc level during inflammatory and infectious diseases. PubMed, Scopus, and Web of Science databases were screened systematically with the terms "zinc supplementation" AND "CRP" OR "IL-1β" OR "IL-2" OR "IL-6" OR "IL-10" OR "IL-12" OR "TNF-α" OR "TGF-β" OR "IFN-γ" OR "WBC (clinical trial)" OR "macrophage (clinical trial)" OR "lymphocyte (clinical trial)" OR "neutrophil (clinical trial)" OR "virus (clinical trial)" OR "antiviral (clinical trial)" for all databases. A total of 2,258 publications were screened, and 73 articles had suitable data for the meta-analysis. Serum zinc level was significantly higher in supplementation group compared with controls [P = 0.0006, mean difference: 11.35 (4.84, 17.87)] (n = 37). Zinc supplementation downregulates acute-phase reactants, especially serum C-reactive protein (CRP) in adults [P < 0.00001, mean difference: -0.75 (-0.98, -0.52)] (n = 22) and pregnant women [FEM P < 0.00001, mean difference: -1.77 (-2.53, -1.00)] (n = 3) but not in children [REM P = 0.10, mean difference: -0.85 (-1.86, 0.17)] (n = 3). In subgroups analysis of chronic inflammatory diseases, serum CRP [REM P < 0.00001, mean difference: -0.57 (-0.76, -0.38)] were significantly lower in zinc-supplemented patients compared with no intervention group. Zinc supplementation (mg/day) correlated with serum interferon-gamma (IFN-γ) level (P = 0.018, r = 1,000). In the nonsupplemented group, serum zinc correlated with serum interleukin-6 (IL-6) level (P = 0.041, r = -0.829) and serum tumor necrosis factor alpha (TNF-α) level (P = 0.063, r = 0.730). Zinc intake correlated with serum zinc (P = 0.0428, r = 0.5115) and TNF-α (P = 0.0043, r = -0.9461). This meta-analysis shows that zinc supplementation improves CRP levels in adults and pregnant women. It might have modulatory effects on cytokine secretions and blood cells in inflammatory and infectious diseases. For the first time, we investigated the effects of zinc supplementation on inflammatory cytokine.

Effects of Dose and Duration of Zinc Interventions on Risk Factors for Type 2 Diabetes and Cardiovascular Disease: A Systematic Review and Meta-Analysis

No meta-analysis has examined the effect of dose and duration of zinc interventions on their impact on risk factors for type 2 diabetes (T2D) or cardiovascular disease (CVD). This study aimed first to compare the effects of zinc interventions dichotomized as low versus high dose (<25 mg/d and ≥25 mg/d, respectively) and short versus long duration (<12 wk and ≥12 wk, respectively) on risk factors for T2D and CVD. Second, it discusses the results from the low-dose and long-duration meta-analyses as a foundation for understanding what impact a zinc-biofortification intervention could have on these risk factors. The PubMed and Cochrane Review databases were searched through January 2020 for full-text, human studies providing zinc supplements (alone) at doses ≤75 mg/d and a placebo. Data on study and sample characteristics and several T2D and CVD risk factors were extracted. There were 1042 and 974 participants receiving zinc and placebo, respectively, from 27 studies. Low-dose zinc supplementation (<25 mg/d) significantly benefited fasting blood glucose, insulin resistance, triglycerides, total cholesterol, and LDL cholesterol. High-dose zinc supplementation (≥25 mg/d) benefited glycated hemoglobin and insulin resistance. Short-duration interventions (<12 wk) benefited fasting blood glucose, insulin resistance, and triglycerides, while long-duration studies (≥12 wk) benefited fasting blood glucose, triglycerides, and total and LDL cholesterol. Effect sizes for low-dose and long-duration interventions were of equal or greater magnitude to those from high-dose or short-duration interventions. Low-dose and long-duration zinc supplementation each improved more risk factors for T2D and CVD than high-dose and short-duration interventions, respectively. It is currently unknown whether low doses of zinc delivered over long durations via a biofortified crop would similarly impact these risk factors. However, this review suggests that low-dose, long-duration zinc intake from supplements, and potentially biofortification, can benefit risk factors for T2D and CVD.

Zinc supplementation and immune factors in adults: a systematic review and meta-analysis of randomized clinical trials

PURPOSE

This systematic review and meta-analysis aimed to investigate the effect of zinc supplementation on immune factors in randomized controlled trials.

METHODS

A comprehensive search was done in PubMed, Scopus, Web of Science, Embase, and Cochrane databases up to December 2020. We used standard and weighted mean differences and 95% confidence intervals for net changes in selected parameters of immune responses. Subgroup analysis was used to find heterogeneity.

RESULT

Overall, 35 RCTs comprising 1995 participants were eligible for this meta-analysis. There was a significant reduction of circulating CRP (WMD: -32.4; 95% CI: -44.45 to -19.62, p < 0.001), hs-CRP (WMD: -0.95; 95% CI: -1.01 to -0.89, p < 0.001), Neutrophil levels (SMD: -0.46; 95% CI: -0.90 to -0.01, p = 0.043), following zinc supplementation. CD4 level also increased significantly, (WMD: 1.79; 95% CI: 0.57 to 3, p = 0.004). Zinc supplementation had no significant effect on WBC (SMD: -0.66; 95% CI: -1.67 to 0.36, p = 0.204), lymphocyte (WMD: 1.86; 95% CI: -0.86 to 4.58, p = 0.181), monocyte levels (SMD: -0.16; 95% CI: -0.07 to 0.39, p = 0.167), CD3 (SMD: 0.37; 95% CI: -0.49 to 1.22, p = 0.399).

CONCLUSION

Zinc supplementation decreased the CRP, hs-CRP and TNF-α, IL-6, neutrophil and increased CD3 and CD4 level significantly.

Zinc supplementation is associated with a reduction in serum markers of inflammation and oxidative stress in adults: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Zinc (Zn) is a trace metal that is considered to have an impact on chronic inflammation. However, findings of clinical trials have been inconsistent. The present systematic review and meta-analysis aimed to provide a more robust examination of the evidence on the effectiveness of Zn supplements on markers of inflammation and oxidative stress.

METHODS

A systematic search in PubMed, Scopus, Web of Science and Cochrane Library was undertaken to identify relevant randomized controlled trials (RCTs) assessing the impact of Zn on inflammation and oxidative stress until 17 August 2020. We applied a random-effects method to obtain effect sizes (ES) and 95% confidence intervals (CIs). Meta-regression was used to detect the potential source of between-study heterogeneity.

RESULTS

Twenty-one eligible RCTs comprising 1321 participants were included in the meta-analysis. In comparison with the control groups, serum C-reactive protein (CRP) (ES = -0.92 mg/L, 95% CI = [-1.36, -0.48], P < 0.001, I² = 90.2%), tumor necrosis factor-alpha (TNF-α) (ES = -0.49 pg/mL, 95% CI = [-084, -0.14], P = 0.006, I² = 34.6%) and malondialdehyde (MDA) (ES = -0.42, 95% CI = [-083, -0.01], P = 0.04, I² = 76.1%) were significantly reduced in the groups receiving Zn. Serum interleukin 6 (ES = -1.02 pg/mL, 95% CI = [-2.06, 0.02], P = 0.05, I² = 92.3%) was marginally reduced following Zn supplementation. Moreover, treatment duration was found as the source of inter-study heterogeneity.

CONCLUSION

This meta-analysis suggests that Zn supplements reduce serum concentrations of markers of inflammation and oxidation: CRP, TNF-α and MDA.

The effects of zinc supplementation on metabolic profile and oxidative stress in overweight/obese patients with non-alcoholic fatty liver disease: A randomized, double-blind, placebo-controlled trial

BACKGROUND

Evidence indicates the positive effects of zinc on insulin resistance and oxidative stress in metabolic syndrome or diabetes. Non-alcoholic fatty liver disease (NAFLD) is the main hepatic manifestation of insulin resistance and metabolic syndrome. The present study is the first clinical trial that evaluated the effects of zinc supplementation on metabolic and oxidative stress status in overweight/obese patients with NAFLD undergoing calorie- restriction diet.

METHODS

Fifty six overweight/obese patients with confirmed mild to moderate NAFLD using ultrasonography were randomly allocated to receive 30 mg elemental zinc supplement (n = 29) or placebo (n = 27) along with weight loss diet for 12 weeks. Serum levels of zinc, homeostasis model of assessment-estimated insulin resistance (HOMA-IR), lipid profile, serum superoxide dismutas1 (SOD1) and malondialdhyde (MDA) levels were assessed.

RESULTS

Serum levels of insulin, SOD1, MDA and HOMA-IR were improved in the treatment group (p < 0.05). Within group comparison showed significant reduction in serum FBS, HbA_1C, TC, LDL-c and TG in the treatment group.

CONCLUSION

Zinc supplementation for three months improved insulin resistance and oxidative stress status in overweight/obese NAFLD patients with no beneficial effects on lipid profiles over weight loss diet. Registration ID in IRCT (IRCT NO: 20181005041238N1).

Adaptation and validity assessment of a diet quality index for patients with type 2 diabetes

PURPOSE

As diet quality indices (DQI) are likely to be influenced by disease background, adapting the existing indices for each disease is crucial. No study has been adapted a DQI for patients with type 2 diabetes. We aimed to adapt healthy eating index and assess its validity for Iranian patients with type 2 diabetes mellitus (T2DM).

METHODS

In this cross-sectional study, the analysis was conducted on 489 adults with T2DM. We adapted HEI and assessed its validity using construct validity. Construct validity was assessed using a 168-item semi-quantitative food-frequency questionnaire (FFQ). General linear model was used to assess associations between adapted HEI scores and demographic characteristics, anthropometric indices, physical activity and food and nutrient intakes.

RESULTS

Adapted HEI were examined on 489 subjects (163 men and 326 women). Findings showed that in older subjects the mean adapted HEI score was greater than the younger ones. However, it was significant only in women (p = 0.01). Women with higher education level obtained the greater score (p < 0.001). The greatest mean score of the adapted HEI score in men was related to non-smokers. The mean score in both genders were raised following the increase in physical activity level (p < 0.05). Moreover, a reduction in the mean score of adapted HEI was observed in men with higher BMI compared to those with the lower one (p = 0.001).

CONCLUSION

Adapted HEI could successfully discriminate diet quality in patients with T2DM. Older and high-educated women were adhered greatly to high quality diets. The adapted DQI linked with greater physical activity level and non-smokers diabetic men with lower BMI.

Diabetes and zinc dyshomeostasis: Can zinc supplementation mitigate diabetic complications?

Zinc present in the islet cells of the pancreas is crucial for the synthesis, storage, and secretion of insulin. The excretion of large amounts of zinc from the body is reported in diabetic situations. Zinc depletion and increased oxidative stress have a major impact on the pathogenesis of diabetic complications. It would be most relevant to ascertain if intervention with supplemental zinc compensating for its depletion would beneficially mitigate hyperglycemia and the attendant metabolic abnormalities, and secondary complications in diabetes. An exhaustive literature search on this issue indicates: (1) Concurrent hypozincemia and decreased tissue zinc stores in diabetes as a result of its increased urinary excretion and/or decreased intestinal absorption, (2) Several recent experimental studies have documented that supplemental zinc has a potential hypoglycemic effect in the diabetic situation, and also beneficially modulate the attendant metabolic abnormalities and compromised antioxidant status, and (3) Supplemental zinc also alleviates renal lesions, cataract and the risk of cardiovascular disease accompanying diabetes mellitus, and help restore gastrointestinal health in experimental diabetes. These studies have also attempted to identify the precise mechanisms responsible for zinc-mediated beneficial effects in diabetic situation. The evidence discussed in this review highlights that supplemental zinc may significantly contribute to its clinical application in the management of diabetic hyperglycemia and related metabolic abnormalities, and in the alleviation of secondary complications resulting from diabetic oxidative stress.

Effects of zinc supplementation on lipid profile in patients with type 2 diabetes mellitus: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND AND AIM

Findings on the effects of zinc supplementation on the lipid profile in patients with type 2 diabetes mellitus (T2DM) are conflicting. The current comprehensive systematic review and meta-analysis aimed to summarize available evidence in this regard.

METHODS AND RESULTS

After a systematic search in the online databases, we included the randomized controlled trials (RCTs) investigating the effect of zinc supplementation on lipid profile [total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and triglyceride (TG)] in patients with T2DM. Altogether, 9 studies with a total sample size of 424 patients with T2DM were included in the analysis. Combining 9 effect sizes from 9 RCTs, we found a significant lowering effect of zinc supplementation on serum levels of TG (weighted mean difference (WMD): -17.08, 95% CI: -30.59, -3.58 mg/dL, P = 0.01) and TC (WMD: -26.16, 95% CI: -49.69, -2.62 mg/dL, P = 0.02). Although the overall effect of zinc supplementation on LDL-C levels was not significant, a beneficial effect was seen in studies that administered <100 mg/d zinc. Based on the non-linear dose-response analysis, a greater reduction in serum levels of TC and LDL-C following zinc supplementation was seen at <12 weeks' duration of intervention. Unlike the overall effect size, we found a significant increasing effect of zinc supplementation on serum HDL-C concentrations in most subgroups of RCTs according to the subgroup analyses.

CONCLUSION

We found that zinc supplementation may beneficially influence lipid profile in patients with T2DM.

Oral Magnesium Supplementation Improved Lipid Profile but Increased Insulin Resistance in Patients with Diabetic Nephropathy: a Double-Blind Randomized Controlled Clinical Trial

Low serum magnesium concentrations were associated with development of renal failure. We aimed to determine whether magnesium supplementation improves renal function, insulin resistance, and metabolic profiles in patients with diabetic nephropathy. A total of 80 hypomagnesemic patients diagnosed with type 2 diabetes and early-stage nephropathy were recruited. Subjects received either daily magnesium oxide or placebo for 12 weeks. Biochemical and anthropometric variables were measured. Physical activity and dietary intakes were also recorded. This study was approved by the ethics committee of Isfahan University of Medical Sciences and was registered on the Iranian Registry of Clinical Trials website (IRCT registration no. IRCT201404271485N12). Serum magnesium levels were not changed significantly. Although the supplementation did not influence glycemic indices, patients in the magnesium group had greater insulin resistance compared with the placebo group after intervention (0.3 ± 2.3 μIU/mL vs. - 0.04 ± 2.05, P = 0.04). No significant changes were observed in serum total cholesterol, triglycerides, HDL, LDL, and total cholesterol/HDL cholesterol ratio. Furthermore, magnesium did not affect inflammation, serum levels of creatinine, and blood urine nitrogen. However, a marginal decrease in microalbuminuria (- 3.1 ± 2.2 mg/L vs. - 14 ± 9.9, P = 0.09) was observed. Oral magnesium supplementation slightly improved microalbuminuria but resulted in increased insulin resistance in patients with diabetic nephropathy.

Zinc supplementation improves glucose homeostasis in patients with β-thalassemia major complicated with diabetes mellitus: A randomized controlled trial

OBJECTIVES

The development of abnormal glucose tolerance in β-thalassemia major (β-TM) is associated with alterations in the oxidant-antioxidant status. Zinc is an antioxidant and an essential element for insulin synthesis, storage, and secretion. This randomized controlled trial assessed the effect of oral zinc supplementation on glucose homeostasis in pediatric β-TM patients complicated with diabetes mellitus (DM).

METHODS

Eighty patients were randomly assigned into two groups: an intervention group that received oral zinc in a dose of 40 mg/d for 12 wk and a placebo group. Hemolysis markers, serum ferritin, fasting blood glucose (FBG), fructosamine, fasting C-peptide, urinary albumin excretion (UAE), and serum zinc levels were assessed. Homeostasis model assessment insulin resistance index (HOMA-IR) was calculated.

RESULTS

Baseline clinical and laboratory parameters were consistent among both groups. Baseline zinc levels were decreased in both groups compared with control values. After 12 wk, supplementation with zinc for the intervention group resulted in a significant decrease in lactate dehydrogenase, serum ferritin, FBG, fructosamine, HOMA-IR, and UAE, whereas fasting C-peptide was higher compared with baseline levels and with the placebo group (P < 0.05). Baseline serum zinc was negatively correlated to FBG (r = -0.534, P < 0.001) and fructosamine (r = -0.555, P < 0.001) but positively correlated to fasting C-peptide (r = 0.777, P = 0.002).

CONCLUSIONS

Zinc supplementation as an adjuvant therapy in β-TM patients with DM reduced iron burden, decreased hyperglycemia, increased insulin secretion, and improved glycemic control without any adverse effects.

Attenuation Effects of Bulk and Nanosized ZnO on Glucose, Lipid Level, and Inflammation Profile in Obese Mice

ZnO and ZnO nanoparticles (ZnO NPs) are widely used in food packaging, food preservation, cosmetic preparation, and animal feed. ZnO is alleged showing multiple bioactivities including antimicrobial and anti-inflammation. It is hypothesized in this study that bulk ZnO and ZnO NPs could attenuate symptoms associated with high-fat-diet-induced obesity. Bulk ZnO and ZnO NPs with diameters of 30 and 90 nm were administered to high-fat-diet (HFD)-induced obese mice. Body weight, liver and fat tissue indices of ZnO-treated mice were decreased compared with those of obese mice (MOD). Blood glucose levels in oral glucose tolerant test and insulin tolerant test of ZnO-treated mice were lower than those of MOD. Serum lipid profile of ZnO-treated mice was ameliorated with lower total cholesterol, total triglyceride, and low-density lipoprotein cholesterol levels compared with that of MOD. In addition, the levels of serum IL-1β and LPS-binding protein were also decreased by ZnO treatment. Both bulk and nanosized ZnO could attenuate HFD-induced phenotypes related with obesity, but ZnO NP is more efficient to lower the fat index and bulk ZnO is better to restore the disturbed serum lipid profile.

The effects of zinc supplementation on clinical response and metabolic profiles in pregnant women at risk for intrauterine growth restriction: a randomized, double-blind, placebo-controlled trial

OBJECTIVE

This investigation was conducted to assess the effects of zinc supplementation on clinical response and metabolic status among pregnant women at risk for intrauterine growth restriction (IUGR).

METHODS

This randomized, double-blind, placebo-controlled, clinical trial was conducted among 52 women at risk for IUGR according to abnormal uterine artery Doppler waveform. Participants were randomly assigned to take either 233 mg zinc gluconate (containing 30 mg zinc) supplements (n = 26) or placebo (n = 26) for 10 weeks from 17 to 27 weeks of gestation. Fasting blood samples were taken at baseline and after the 10-week treatment to quantify related variables.

RESULTS

After the 10-week intervention, taking zinc led to a significant reduction in serum high-sensitivity C-reactive protein (hs-CRP) (β ‒1.17 mg/L; 95% CI, -1.77, -0.57; p < .001) and plasma malondialdehyde (MDA) levels (β -0.23 µmol/L; 95% CI, -0.45, -0.02; p = .03); also a significant rise in total antioxidant capacity (TAC) (β 59.22 mmol/L; 95% CI, 25.07, 93.36; p = .001) was observed in comparison to placebo. In addition, zinc supplementation significantly reduced serum insulin (β -1.33 µIU/mL; 95% CI, -2.00, -0.67; p < .001) and insulin resistance (β -0.30; 95% CI, -0.44, -0.15; p < .001), and significantly increased insulin sensitivity (β 0.008; 95% CI, 0.003, 0.01; p < .001) compared with the placebo. Zinc supplementation did not influence pulsatility index (PI) and other metabolic parameters.

CONCLUSIONS

Overall, zinc supplementation in pregnant women at risk for IUGR had beneficial effects on TAC, MDA, hs-CRP, and insulin metabolism, but did not affect PI and other metabolic profiles.

Zinc supplementation improves glycemic control for diabetes prevention and management: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Although many studies have shown that low zinc status is associated with diabetes, the putative effects of zinc supplementation on glycemic control are inconclusive.

OBJECTIVES

The aim of this meta-analysis of randomized controlled trials was to assess the effects of zinc supplementation in preventing and managing diabetes.

METHODS

PubMed, Embase, and the Cochrane Library were searched for articles that were published through February 10, 2019 and contained estimates for the outcomes of interest. The pooled results were then analyzed with the use of a random-effects model.

RESULTS

Thirty-two placebo-controlled interventions were extracted from 36 publications, involving a total of 1700 participants in 14 countries. Overall, compared with their respective control groups, the subjects in the zinc-supplementation group had a statistically significant reduction in fasting glucose [FG, weighted mean difference (WMD): -14.15 mg/dL; 95% CI: -17.36, -10.93 mg/dL], 2-h postprandial glucose (WMD: -36.85 mg/dL; 95% CI: -62.05, -11.65 mg/dL), fasting insulin (WMD: -1.82 mU/L; 95% CI: -3.10, -0.54 mU/L), homeostasis model assessment for insulin resistance (WMD: -0.73; 95% CI: -1.22, -0.24), glycated hemoglobin (WMD: -0.55%; 95% CI: -0.84, -0.27%), and high-sensitivity C-reactive protein (WMD: -1.31 mg/L; 95% CI: -2.05, -0.56 mg/L) concentrations. Moreover, subgroup analyses revealed that the effects of zinc supplementation on FG are significantly influenced by diabetic status and the formulation of the zinc supplement.

CONCLUSIONS

Our analysis revealed that several key glycemic indicators are significantly reduced by zinc supplementation, particularly the FG in subjects with diabetes and in subjects who received an inorganic zinc supplement. Together, these findings support the notion that zinc supplementation may have clinical potential as an adjunct therapy for preventing or managing diabetes. This trial was registered at PROSPERO as CRD42018111838.

Meta-Analysis: Effects of Zinc Supplementation Alone or with Multi-Nutrients, on Glucose Control and Lipid Levels in Patients with Type 2 Diabetes

The present study aims to assess the effects of zinc supplementation on metabolic parameters in patients with type 2 diabetes. A literature search was conducted in PubMed^TM, Google Scholar^TM, and Scopus^TM up to March 2018. Twenty randomized controlled trials met the predefined inclusion criteria and were included in the meta-analysis. Weighted mean difference (WMD) with 95% confidence intervals (CIs) were calculated for net changes in glycemic indices including fasting blood glucose (FBG) and hemoglobin A1c (HbA1c), and in lipid markers including total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-c), and high density lipoprotein cholesterol (HDL-c). Subgroup analyses were performed based on intervention and study quality. Compared to controls, zinc supplementation significantly reduced the concentrations of both FBG and HbA1c (FBG WMD: −19.66 mg/dL, 95% CI: −33.71, −5.62; HbA1c WMD: −0.43 mg/dL, 95% CI: −0.80, −0.07). The pooled estimate showed a significant decrease in serum TC and LDL-c, and increase in serum HDL-c levels in treatment group compared with the control group (TC WMD: −18.51 mg/dL, 95% CI: −21.36, −15.66; LDL-c WMD: −4.80 mg/dL, 95% CI: −6.07, −3.53; HDL-c WMD: 1.45 mg/dL, 95% CI: 1.40, 1.51). Subgroup analysis of “no co-supplement” intervention demonstrated significant differences for mean changes in HDL-c and FBG levels, whereas subgroup analysis of high quality studies showed significant differences for mean changes of LDL-c, HDL-c, and FBG levels. Results suggested that zinc supplementation reduces FBG, HbA1c and LDL-c levels and increases HDL-C levels; however, these changes were related to intervention and quality of studies.

The effect of zinc supplementation on plasma C-reactive protein concentrations: A systematic review and meta-analysis of randomized controlled trials

Previous studies have shown zinc has potential anti-inflammatory and anti-oxidative effects. However, findings from clinical trials about the effect of zinc on plasma C-reactive protein (CRP) appeared inconsistent and uncertain. Therefore, the aim of this meta-analysis was to summarize the effect of zinc supplementation on plasma CRP concentrations in adults. The literature search through PubMed, SCOPUS, and Google Scholar were done to find published studies up to October 2017. Random or fixed-effects model depending on the results of heterogeneity tests were used to estimate the pooled effect size. Between-study heterogeneity was assessed using Cochran's Q test and I2 index. Funnel plot and Egger's regression test were used to assess publication bias. Our search found 1505 publications, of which 8 randomized controlled trials (RCTs) were eligible to be included in the analysis. The results of the meta-analysis displayed a significant reduction in circulating CRP levels (WMD: - 1.68 mg/l; 95% CI: - 2.4 to - 0.9, P = <0.001) following zinc supplementation. In the subgroup analysis, supplementation dosage, study quality, study population, and baseline CRP level were the potential sources of heterogeneity. Participants took equal to 50 mg/d zinc (WMD: - 1.97 mg/l; 95% CI: - 2.28 to - 1.67, P = <0.001), low quality studies (WMD: - 2.9 mg/l; 95% CI: - 3.68 to - 2.12, P = <0.001) and those with renal dysfunction (WMD: - 7.43 mg/l; 95% CI: - 12.57 to -2.29, P = 0.005) showed greater improvement in CRP levels. In conclusion, zinc supplementation may have a beneficial effect on the serum CRP, especially at doses equal to 50 mg/d and in renal insufficiency patients compared with healthy subjects.

Dietary Zinc Intake and Its Association with Metabolic Syndrome Indicators among Chinese Adults: An Analysis of the China Nutritional Transition Cohort Survey 2015

The dietary zinc consumed in Chinese households has decreased over the past decade. However, the national dietary zinc intake in the last five years has seldom been investigated. Using data from 12,028 participants 18 to 64 years old (52.9% male) in the China Nutritional Transition Cohort Survey (CNTCS) 2015, we describe the intake of dietary zinc and the contributions of major foods and we examine the relationship between the level of dietary zinc intake and metabolic syndrome indicators, including blood pressure, fasting glucose, and triglycerides (TG), in Chinese adults. We assessed dietary zinc intake using 24 h recalls on three consecutive days. The mean daily dietary zinc intake for all participants was 10.2 milligrams per day (males 11.2 mg/day, females 9.4 mg/day, p < 0.001). The mean daily dietary zinc density for all participants was 5.2 mg/day per 1000 kilocalories. Among all participants, 31.0% were at risk of zinc deficiency, with dietary zinc intakes of less than the Estimated Average Requirement (EAR) (males 49.2%, females 14.8%, p < 0.050), and 49.9% had adequate dietary zinc intakes, equal to or greater than the recommended nutrient intake (RNI) (males 30.7%, females 67.0%, p < 0.050). We found substantial gender differences in dietary zinc intake and zinc deficiency, with nearly half of the men at risk of zinc deficiency. Males of younger age, with higher education and incomes, and who consumed higher levels of meat, had higher zinc intakes, higher zinc intake densities, and higher rates of meeting the EAR. Among all participants, grains, livestock meat, fresh vegetables, legumes, and seafood were the top five food sources of zinc, and their contributions to total dietary zinc intake were 39.5%, 17.3%, 8.9%, 6.4%, and 4.8%, respectively. The groups with relatively better dietary zinc intakes consumed lower proportions of grains and higher proportions of livestock meat. For males with adequate dietary zinc intake (≥RNI), TG levels increased by 0.219 millimoles per liter (mmol/L) compared with males with deficient dietary zinc intake ( Collapse

Key Words

• Chinese adults
• dietary zinc
• food source
• metabolic syndrome

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MESH Headings

• Adolescent
• Adult
• Asian People
• Blood Glucose/metabolism
• Blood Pressure/drug effects
• Body Mass Index
• China/epidemiology
• Cohort Studies
• Diet
• Dietary Carbohydrates/administration & dosage
• Dietary Fats/administration & dosage
• Dietary Proteins/administration & dosage
• Female
• Humans
• Male
• Metabolic Syndrome/blood
• Metabolic Syndrome/epidemiology
• Middle Aged
• Nutrition Assessment
• Nutritional Status
• Recommended Dietary Allowances
• Socioeconomic Factors
• Triglycerides/blood
• Vegetables
• Young Adult
• Zinc/administration & dosage
• Zinc/blood
• Zinc/deficiency

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Grants Collapse

Affiliation(s)

Yun Wang National Institute for Nutrition and Health, Chinese Center for Disease Control and Prevention, Beijing 100050, China.
Xiao-Fang Jia National Institute for Nutrition and Health, Chinese Center for Disease Control and Prevention, Beijing 100050, China.
Bing Zhang National Institute for Nutrition and Health, Chinese Center for Disease Control and Prevention, Beijing 100050, China.
Zhi-Hong Wang National Institute for Nutrition and Health, Chinese Center for Disease Control and Prevention, Beijing 100050, China.
Ji-Guo Zhang National Institute for Nutrition and Health, Chinese Center for Disease Control and Prevention, Beijing 100050, China.
Fei-Fei Huang National Institute for Nutrition and Health, Chinese Center for Disease Control and Prevention, Beijing 100050, China.
Chang Su National Institute for Nutrition and Health, Chinese Center for Disease Control and Prevention, Beijing 100050, China.
Yi-Fei Ouyang National Institute for Nutrition and Health, Chinese Center for Disease Control and Prevention, Beijing 100050, China.
Jian Zhao National Institute for Nutrition and Health, Chinese Center for Disease Control and Prevention, Beijing 100050, China.
Wen-Wen Du National Institute for Nutrition and Health, Chinese Center for Disease Control and Prevention, Beijing 100050, China.
Li Li National Institute for Nutrition and Health, Chinese Center for Disease Control and Prevention, Beijing 100050, China.
Hong-Ru Jiang National Institute for Nutrition and Health, Chinese Center for Disease Control and Prevention, Beijing 100050, China.
Ji Zhang National Institute for Nutrition and Health, Chinese Center for Disease Control and Prevention, Beijing 100050, China.
Hui-Jun Wang National Institute for Nutrition and Health, Chinese Center for Disease Control and Prevention, Beijing 100050, China.

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The beneficial effects of Zn on Akt-mediated insulin and cell survival signaling pathways in diabetes

Zinc is one of the essential trace elements and participates in numerous physiological processes. Abnormalities in zinc homeostasis often result in the pathogenesis of various chronic metabolic disorders, such as diabetes and its complications. Zinc has insulin-mimetic and anti-diabetic effects and deficiency has been shown to aggravate diabetes-induced oxidative stress and tissue injury in diabetic rodent models and human subjects with diabetes. Akt signaling pathway plays a central role in insulin-stimulated glucose metabolism and cell survival. Anti-diabetic effects of zinc are largely dependent on the activation of Akt signaling. Zn is also an inducer of metallothionein that plays important role in anti-oxidative stress and damage. However, the exact molecular mechanisms underlying zinc-induced activation of Akt signaling pathway remains to be elucidated. This review summarizes the recent advances in deciphering the possible mechanisms of zinc on Akt-mediated insulin and cell survival signaling pathways in diabetes conditions. Insights into the effects of zinc on epigenetic regulation and autophagy in diabetic nephropathy are also discussed in the latter part of this review.

Zinc transporters and insulin resistance: therapeutic implications for type 2 diabetes and metabolic disease

BACKGROUND

Zinc is a metal ion that is essential for growth and development, immunity, and metabolism, and therefore vital for life. Recent studies have highlighted zinc's dynamic role as an insulin mimetic and a cellular second messenger that controls many processes associated with insulin signaling and other downstream pathways that are amendable to glycemic control.

MAIN BODY

Mechanisms that contribute to the decompartmentalization of zinc and dysfunctional zinc transporter mechanisms, including zinc signaling are associated with metabolic disease, including type 2 diabetes. The actions of the proteins involved in the uptake, storage, compartmentalization and distribution of zinc in cells is under intense investigation. Of these, emerging research has highlighted a role for several zinc transporters in the initiation of zinc signaling events in cells that lead to metabolic processes associated with maintaining insulin sensitivity and thus glycemic homeostasis.

CONCLUSION

This raises the possibility that zinc transporters could provide novel utility to be targeted experimentally and in a clinical setting to treat patients with insulin resistance and thus introduce a new class of drug target with utility for diabetes pharmacotherapy.

Implications of impaired zinc homeostasis in diabetic cardiomyopathy and nephropathy

Impaired zinc homeostasis is observed in diabetes mellitus (DM2) and its complications. Zinc has a specific role in pancreatic β-cells via insulin synthesis, storage, and secretion. Intracellular zinc homeostasis is tightly controlled by zinc transporters (ZnT and Zip families) and metallothioneins (MT) which modulate the uptake, storage, and distribution of zinc. Several investigations in animal models demonstrate the protective role of MT in DM2 and its cardiovascular or renal complications, while a copious literature shows that a common polymorphism (R325W) in ZnT8, which affects the protein's zinc transport activity, is associated with increased DM2 risk. Emerging studies highlight a role of other zinc transporters in β-cell function, suggesting that targeting them could make a possible contribution in managing the hyperglycemia in diabetic patients. This article summarizes the current findings concerning the role of zinc homeostasis in DM2 pathogenesis and development of diabetic cardiomyopathy and nephropathy and suggests novel therapeutic targets. © 2017 BioFactors, 43(6):770-784, 2017.

Chronic High Dose Zinc Supplementation Induces Visceral Adipose Tissue Hypertrophy without Altering Body Weight in Mice

The trace element zinc plays an important role in human life. Zinc deficiency impairs growth, reproduction, metabolism and immunity in both human and animals. Thus, zinc supplementation is recommended in daily life. However, the effect of long-term chronic zinc supplementation on adipose homeostasis has not been well elucidated. In the current study, mice were supplemented with zinc sulfate in the drinking water for 20 weeks. The results suggested that chronic zinc supplementation impaired systemic glucose clearance after exogenous insulin or glucose challenges, as compared to the control mice. Further study revealed that chronic zinc supplementation made no difference to body weight, but increased visceral adipose tissue weight and adipocyte size. In addition, gene expression of leptin and IL6 in the visceral adipose tissue of zinc-supplemented mice were higher than those of control mice. Moreover, serum level of leptin of the zinc-supplemented mice was twice as high as that of the control mice. Besides, phosphorylation level of AKT T308 was attenuated in the perirenal adipose tissue of zinc-supplemented mice. In comparison, the expression of macrophage marker genes and lipogenic genes were not affected by chronic zinc supplementation, but the protein levels of FAS and SCD1 decreased or tended to decrease in the perirenal adipose tissue of zinc-supplemented mice, as compared to the control mice. Our findings suggest that chronic high dose zinc supplementation induces visceral adipose tissue hypertrophy and impairs AKT signaling in perirenal adipose tissue.

Zinc status is associated with inflammation, oxidative stress, lipid, and glucose metabolism

A number of studies have reported that zinc plays a substantial role in the development of metabolic syndrome, taking part in the regulation of cytokine expression, suppressing inflammation, and is also required to activate antioxidant enzymes that scavenge reactive oxygen species, reducing oxidative stress. Zinc also plays a role in the correct functioning of lipid and glucose metabolism, regulating and forming the expression of insulin. In numerous studies, zinc supplementation has been found to improve blood pressure, glucose, and LDL cholesterol serum level. Deeper knowledge of zinc’s properties may help in treating metabolic syndrome, thus protecting against stroke and angina pectoris, and ultimately against death.

Antioxidant agents for delaying diabetic kidney disease progression: A systematic review and meta-analysis

BACKGROUND

Oxidative stress is a key player in the genesis and worsening of diabetic kidney disease (DKD). We aimed at collecting all available information on possible benefits of chronic antioxidant supplementations on DKD progression.

STUDY DESIGN

Systematic review and meta-analysis.

POPULATION

Adults with DKD (either secondary to type 1 or 2 diabetes mellitus).

SEARCH STRATEGY AND SOURCES

Cochrane CENTRAL, Ovid-MEDLINE and PubMed were searched for randomized controlled trials (RCTs) or quasi-RCTs without language or follow-up restriction.

INTERVENTION

Any antioxidant supplementation (including but not limited to vitamin A, vitamin C, vitamin E, selenium, zinc, methionine or ubiquinone) alone or in combination.

OUTCOMES

Primary outcome was progression to end-stage kidney disease (ESKD). Secondary outcomes were change in albuminuria, proteinuria, serum creatinine and renal function.

RESULTS

From 13519 potentially relevant citations retrieved, 15 articles referring to 14 full studies (4345 participants) met the inclusion criteria. Antioxidant treatment significantly decreased albuminuria as compared to control (8 studies, 327 participants; SMD: -0.47; 95% CI -0.78, -0.16) but had apparently no tangible effects on renal function (GFR) (3 studies, 85 participants; MD -0.12 ml/min/1.73m2; 95% CI -0.06, 0.01). Evidence of benefits on the other outcomes of interest was inconclusive or lacking.

LIMITATIONS

Small sample size and limited number of studies. Scarce information available on hard endpoints (ESKD). High heterogeneity among studies with respect to DKD severity, type and duration of antioxidant therapy.

CONCLUSIONS

In DKD patients, antioxidants may improve early renal damage. Future studies targeting hard endpoints and with longer follow-up and larger sample size are needed to confirm the usefulness of these agents for retarding DKD progression.

Natural antioxidants in the treatment and prevention of diabetic nephropathy; a potential approach that warrants clinical trials

Diabetic nephropathy is the major cause of end-stage renal disease and effective and new therapeutic approaches are needed in diabetic nephropathy and chronic kidney diseases. Oxidative stress and inflammatory process are important factors contributing to kidney damage by increasing production of oxidants. KEAP1/Nrf2/ARE pathway regulates the transcription of many antioxidant genes and modulation of the pathway up regulates antioxidants. NFB controls the expression of genes involved in the inflammatory response. Natural substances have antioxidant and anti-inflammatory activities and have an impact on NFB and KEAP1/Nrf2/ARE pathways. The preclinical studies explored the effectiveness of whole herbs, plants or seeds and their active ingredients in established diabetic nephropathy. They ameliorate oxidative stress induced kidney damage, enhance antioxidant system, and decrease inflammatory process and fibrosis; most likely by activating KEAP1/Nrf2/ARE pathway and by deactivating NFB pathway. Whole natural products contain balanced antioxidants that might work synergistically to induce beneficial therapeutic outcome. In this context, more clinical studies involving whole plants or herbal products or mixtures of different herbs and plants and their active ingredients might change our strategies for the management of diabetic nephropathy. The natural products might be useful as preventive interventions and studies are required in this field.

The effects of zinc supplementation on wound healing and metabolic status in patients with diabetic foot ulcer: A randomized, double-blind, placebo-controlled trial

This study was performed to determine the effects of zinc supplementation on wound healing and metabolic status in patients with diabetic foot ulcer. The current randomized, double-blind, placebo-controlled trial was conducted among 60 patients (aged 40-85 years old) with grade 3 diabetic foot ulcer. Participants were randomly divided into two groups (30 participants in each group) to take either 220 mg zinc sulfate supplements containing 50 mg elemental zinc or placebo daily for 12 weeks. After the 12-week intervention, compared with the placebo, zinc supplementation was associated with significant reductions in ulcer length (-1.5 ± 0.7 vs. -0.9 ± 1.2 cm, p = 0.02) and width (-1.4 ± 0.8 vs. -0.8 ± 1.0 cm, p = 0.02). In addition, changes in fasting plasma glucose (-40.5 ± 71.0 vs. -3.9 ± 48.5 mg/dl, p = 0.02), serum insulin concentration (-8.0 ± 15.4 vs. +1.1 ± 10.3 µIU/ml, p = 0.009), homeostasis model of assessment-estimated insulin resistance (-3.9 ± 7.1 vs. +0.8 ± 5.9, p = 0.007), the quantitative insulin sensitivity check index (+0.01 ± 0.03 vs. -0.002 ± 0.02, p = 0.04) and HbA1c (-0.5 ± 0.8 vs. -0.1 ± 0.5%, p = 0.01) in the supplemented group were significantly different from the changes in these indicators in the placebo group. Additionally, significant increases in serum HDL-cholesterol (+4.1 ± 4.3 vs. +1.1 ± 5.1 mg/dl, p = 0.01), plasma total antioxidant capacity (+91.7 ± 213.9 vs. -111.9 ± 188.7 mmol/L, p < 0.01) and total glutathione (+68.1 ± 140.8 vs. -35.0 ± 136.1 µmol/L, p = 0.006), and significant decreases in high sensitivity C-reactive protein (-20.4 ± 24.6 vs. -6.8 ± 21.3 µg/ml, p = 0.02) and plasma malondialdehyde concentrations (-0.6 ± 0.9 vs. -0.2 ± 0.7 µmol/L, p = 0.03) were seen following supplementation with zinc compared with the placebo. Zinc supplementation for 12 weeks among diabetic foot ulcer patients had beneficial effects on parameters of ulcer size and metabolic profiles.

Zinc rescues obesity-induced cardiac hypertrophy via stimulating metallothionein to suppress oxidative stress-activated BCL10/CARD9/p38 MAPK pathway

Obesity often leads to obesity-related cardiac hypertrophy (ORCH), which is suppressed by zinc-induced inactivation of p38 mitogen-activated protein kinase (p38 MAPK). In this study, we investigated the mechanisms by which zinc inactivates p38 MAPK to prevent ORCH. Mice (4-week old) were fed either high fat diet (HFD, 60% kcal fat) or normal diet (ND, 10% kcal fat) containing variable amounts of zinc (deficiency, normal and supplement) for 3 and 6 months. P38 MAPK siRNA and the p38 MAPK inhibitor SB203580 were used to suppress p38 MAPK activity in vitro and in vivo, respectively. HFD activated p38 MAPK and increased expression of B-cell lymphoma/CLL 10 (BCL10) and caspase recruitment domain family member 9 (CARD9). These responses were enhanced by zinc deficiency and attenuated by zinc supplement. Administration of SB203580 to HFD mice or specific siRNA in palmitate-treated cardiomyocytes eliminated the HFD and zinc deficiency activation of p38 MAPK, but did not significantly impact the expression of BCL10 and CARD9. In cultured cardiomyocytes, inhibition of BCL10 expression by siRNA prevented palmitate-induced increased p38 MAPK activation and atrial natriuretic peptide (ANP) expression. In contrast, inhibition of p38 MAPK prevented ANP expression, but did not affect BCL10 expression. Deletion of metallothionein abolished the protective effect of zinc on palmitate-induced up-regulation of BCL10 and phospho-p38 MAPK. HFD and zinc deficiency synergistically induce ORCH by increasing oxidative stress-mediated activation of BCL10/CARD9/p38 MAPK signalling. Zinc supplement ameliorates ORCH through activation of metallothionein to repress oxidative stress-activated BCL10 expression and p38 MAPK activation.

Relationship Between Serum Zinc Level and Microvascular Complications in Patients with Type 2 Diabetes

Background:

Previous studies suggested that zinc level was related to a certain diabetic microvascular complication. However, the relationship between zinc level and all the microvascular complications in type 2 diabetic patients remains unknown. The purpose of this study was to analyze the relationship between zinc level and each diabetic microvascular complication and identify the features related to low serum zinc level.

Methods:

We included the hospitalized patients with type 2 diabetes (T2D) at our department from May 30, 2013 to March 31, 2014. We initially compared the serum zinc levels between patients with specific microvascular complications and those without. We then analyzed the association between zinc level and each microvascular complication. Furthermore, we identified the unique features of patients with high and low serum zinc levels and analyzed the risk factors related to low zinc level.

Results:

The 412 patients included 271 with microvascular complications and 141 without any microvascular complications. Serum zinc level was significantly lower in patients with diabetic retinopathy (P < 0.001), diabetic nephropathy (DN, P < 0.001), or diabetic peripheral neuropathy (P = 0.002) compared with patients without that specific complication. Lower zinc level was an independent risk factor for DN (odds ratio = 0.869, 95% confidence interval = 0.765–0.987, P < 0.05). The subjects with lower serum zinc level had manifested a longer duration of diabetes, higher level of hemoglobin A1c, higher prevalence of hypertension and microvascular complications, and lower fasting and 2-h C-peptide levels.

Conclusions:

Lower serum zinc level in T2D patients was related to higher prevalence of diabetic microvascular complications, and represented as an independent risk factor for DN. Patients with lower zinc level were more likely to have a longer duration of diabetes, poorer glucose control, and worse β-cell function.

Zinc supplementation alleviates hyperglycemia and associated metabolic abnormalities in streptozotocin-induced diabetic rats

The cause and effect relationship between diabetes and zinc is complex and unclear. This animal study has examined the potential of zinc supplementation in beneficial modulating hyperglycemia, insulin secretion, and metabolic abnormalities associated with diabetes. The study was conducted in streptozotocin-induced diabetic rats. Groups of hyperglycemic rats were subjected to dietary interventions for 6 weeks with zinc supplementation (5 times and 10 times the normal level). Supplemental-zinc-fed diabetic groups showed significant control on hyperglycemia and hypoinsulinemia. There was a significant reduction in protein glycosylation, glucosuria, and urinary excretion of proteins and urea in diabetic animals maintained on a zinc-supplemented diet. Diabetic rats showed significantly higher plasma albumin and lower plasma urea and creatinine levels upon zinc supplementation. Significant alterations in insulin sensitivity indices HOMA-IR, HOMA-B, and QUICKI were also indicated by zinc supplementation. The pathological abnormalities in pancreatic islets of diabetic animals were significantly alleviated by dietary zinc intervention. This study provides the first evidence that zinc supplementation can partially ameliorate the severity of diabetic hyperglycemia and associated metabolic abnormalities, hypoinsulinemia, insulin resistance, and altered pancreatic morphology. Thus, zinc supplementation may offer a significant potential for clinical application in managing diabetic hyperglycemia and related metabolic complications.

Serum Zn/Cu Ratio Is Associated with Renal Function, Glycemic Control, and Metabolic Parameters in Japanese Patients with and without Type 2 Diabetes: A Cross-sectional Study

BACKGROUND

Zinc (Zn) and copper (Cu) may play a pivotal role in the pathogenesis of diabetes and diabetic complications by mediating oxidative stress. Both Zn deficiency and excess of Cu are associated with an increased risk of type 2 diabetes and cardiovascular disease. We aimed to investigate the relationships between serum Zn/Cu ratio and glycemic status, renal function, and metabolic parameters in patients with and without type 2 diabetes.

METHODS

We conducted a cross-sectional study on 355 subjects (149 type 2 diabetic and 206 non-diabetic) in whom serum Zn and Cu levels were measured at the same time. Associations between serum Zn/Cu ratio and clinical data were evaluated using multiple regression analysis. We also evaluated associations between serum Zn/Cu ratio and the prevalence of type 2 diabetes and glycemic control by multivariate logistic regression analysis.

RESULTS

Serum Zn/Cu ratio was positively associated with estimated glomerular filtration rate after adjustment for body mass index (BMI) (β = 0.137, p = 0.014). Plasma B-type natriuretic peptide levels were negatively associated with serum Zn/Cu ratio after adjustment for age, sex, and BMI (β = -0.258, p = 0.032). In patients with type 2 diabetes, serum Zn/Cu ratio was negatively associated with plasma HbA1c levels after adjustment for age, sex, and BMI (β = -0.239, p = 0.003). In addition, multivariate logistic regression analysis revealed that the highest quartile of serum Zn/Cu ratio was associated with a reduced risk of poor (HbA1c ≥ 7%) glycemic control (odds ratio = 0.382; 95% confidence interval, 0.165-0.884; p = 0.025) in patients with type 2 diabetes.

CONCLUSION

Serum Zn/Cu ratio was favorably associated with renal function in all subjects and glycemic control in patients with type 2 diabetes. The Zn/Cu ratio, in addition to the individual serum levels of trace elements, is important for metabolism in humans.

Effect of ZIP2 Gln/Arg/Leu (rs2234632) polymorphism on zinc homeostasis and inflammatory response following zinc supplementation

Zinc dyshomeostasis may lead to an augmented production of proinflammatory cytokines promoting chronic inflammation and increasing the susceptibility to age-related diseases. Several studies suggest that the zinc transporter protein ZIP2 may play a relevant role in the immune system especially during zinc deficiency, while a polymorphism on the coding region of ZIP2 gene (Gln/Arg/Leu) has been associated with severe carotid artery disease. The aim of this study is to investigate the role of ZIP2 SNP on zinc and inflammatory status in 1090 elderly healthy free-living subjects enrolled in the ZincAge project and to assess the effect of zinc supplementation on zinc status, inflammatory mediators, and zinc transporter expression depending on ZIP2 genotype. ZIP2 Leu- (Arg43Arg) carriers showed enhanced IL-6, TNF-α, and RANTES plasma levels associated with decreased free cytosolic zinc in PBMCs and an upregulation of zinc transporters ZIP2, ZIP8, and Znt1. Moreover, Leu- subjects displayed significant decrement of inflammatory mediators such as MCP-1, TNF-α, and RANTES following zinc supplementation. In summary, this investigation provides new evidence on the effect of ZIP2 Gln/Arg/Leu polymorphism on proinflammatory mediators and zinc homeostasis in elderly population with a more pronounced anti-inflammatory effect of zinc supplementation in subjects carrying ZIP2 Leu- (Arg43Arg) genotype. These novel findings could be useful in identifying elderly subjects who may benefit of zinc intervention to decrease the inflammatory status and to prevent or delay the development of age-related diseases.

Intake of Vitamin and Mineral Supplements and Longitudinal Association with HbA1c Levels in the General Non-Diabetic Population--Results from the MONICA/KORA S3/F3 Study

Background

Lower levels of hemoglobin A_1c (HbA_1c) are associated with a decreased risk of cardiovascular complications in diabetic and non-diabetic individuals. The aim of the study was to longitudinally investigate the association between the use of 11 vitamins and minerals (vitamins E, C, D, B₁, folic acid, carotenoids, calcium, magnesium, zinc, iron, and selenium) and change in HbA_1c levels over 10 years in non-diabetic individuals drawn from the general population.

Methods

Baseline data were available from 4447 subjects included in the population-based “Monitoring of Trends and Determinants in Cardiovascular Diseases” (MONICA) Augsburg S3 survey (1994/95). Follow-up data were derived from 2774 participants in the follow-up survey named “Cooperative Health Research in the Region of Augsburg” (KORA) F3 (2004/05). Vitamin/mineral intake from supplements and medications was assessed in a personal interview, where participants were asked to bring product packages of preparations that had been ingested during the last 7 days prior to the examination. Associations between regular vitamin/mineral intake amounts and HbA_1c levels measured at baseline and follow-up were investigated using generalized estimating equation models. For carotenoids, analyses were stratified by smoking status.

Results

None of the investigated nutrients except for carotenoids was significantly associated with changes in HbA_1c levels after 10 years. Regular intake of carotenoids from supplements and medications in amounts > 6.8mg/d (upper tertile) was associated with an absolute –0.26% (95% CI: –0.43 to –0.08) lower increase in HbA_1c levels compared with no intake of carotenoids. An inverse association was observed in those who never smoked but not in (former) smokers.

Conclusion

Larger prospective and intervention studies in non-diabetic/non-smoking individuals are needed to confirm the results and to assess whether the observed associations between carotenoid intake and change in HbA_1c levels are causal. If our results are confirmed, high carotenoid intake could be one strategy for the prevention of cardiovascular complications in non-diabetic people.