Low dietary zinc alters indices of copper function and status in postmenopausal women

Variations in Blood Copper and Possible Mechanisms During Pregnancy

Copper (Cu), an essential trace element, is crucial for both the mother and fetus. Currently, an increasing number of studies have focused on blood copper levels during pregnancy. Studies have found that blood copper levels in pregnant women are higher than those in reproductive-age women, but the trend, mainly in the 2nd and 3rd trimester, is still controversial. Most studies showed that blood copper levels gradually increased during pregnancy, while some studies found that blood copper levels remained stable or even decreased in the 3rd trimester. The possible mechanisms of variations in blood copper during pregnancy include the influence of estrogen (hepatic uptake and excretion, ceruloplasmin synthesis, maternal-fetal transport, etc.), the interaction of other trace elements (Fe, Zn, etc.) and other factors. Among them, maternal-fetal copper transport caused by elevated estrogen may be the main reason for the inconsistencies observed in the 2nd and 3rd trimester during pregnancy. However, there are some mechanisms require further investigation. In the future, the trend and mechanisms of blood copper during pregnancy should be explored more deeply to help doctors better monitor copper status and detect copper abnormalities in time.

Study of Serum Copper and Zinc Levels and Serum Cu/Zn Ratio among Polish Women with Endometrial Cancer

BACKGROUND

Micronutrients are important components for the homeostasis of the human body. The studies available in the literature of the subject on their impact on the risk of population diseases, including malignant neoplasms, are ambiguous. In this paper, the relationship between Cu and Zn serum levels and the occurrence of endometrial cancer have been analyzed.

METHODS

306 patients (153 test group and 153 control group) matched for age were analyzed for Cu and Zn levels. Microelements levels were determined for sera collected during the hospitalization of patients by means of an inductively coupled plasma mass spectrometry. In addition, the Cu/Zn ratio in the population included in the study was analyzed. Univariable and multivariable analyzes were used to examine the relationship between the factors under study and the incidence of endometrial cancer.

RESULTS

Lower levels of elements were observed in the study group compared with the control group (Cu: 959.39 μg/L vs. 1176.42 μg/L, p < 0.001; Zn: 707.05 μg/L vs. 901.67 μg/L, p < 0.001). A statistically significant relationship with the occurrence of endometrial cancer was observed for Cu and Zn. The patients with the lowest Cu level had a significantly higher occurrence of endometrial cancer compared with reference tertile (OR 8.54; p < 0.001). Similarly, compared with the reference tertile, the patients with the lowest Zn levels had a significantly greater incidence of endometrial cancer (OR 15.0; p < 0.001).

CONCLUSION

The results of the study suggest an association of endometrial cancer occurrence with lower Cu and Zn serum levels.

Concentrations of Mg, Ca, Fe, Cu, Zn, P and anthropometric and biochemical parameters in adults with chronic heart failure

Background

The study investigated the relationship between the concentrations of Mg, Ca, Fe, Cu, Zn, P and anthropometric and biochemical parameters in the blood serum of patients with heart failure (HF) and the potential influence on the development and progression of HF.

Material & methods

The study included 214 patients (155 men and 59 women), aged 40–87 years, presenting symptoms or signs typical of HF (according to the NYHA functional classification). Serum concentrations were determined for Mg, Ca, Fe, Cu, Zn, P, C-reactive protein (CRP), creatinine, urea, triglyceride levels (TG), total cholesterol (CH), high density protein (HDL), low density protein (LDL). The levels of macro-and microminerals were analysed using inductively coupled serum optical emission spectrometry (ICP-OES).

Results

Our study confirmed the role of known risk factors in the development of heart failure, including: overweight, diabetes, hypertension, high triglycerides (TG), high total cholesterol (CH), high levels of low density protein (LDL) and reduced levels of high density protein (HDL), high CRP, high creatinine. Moreover, deficient serum concentrations of Mg (47% of the studied men and 54% of the women) and Cu (in 44% of men and more than 30% of women) were observed, as well as subnormal serum Fe (2% of women) and Zn (1% of men). Elevated serum Ca was found in 50% of men and 49% of women. In 44% of the studied men and 52% of the studied women, P levels in serum were also above-average. The study revealed a significant positive correlation between serum levels of Ca and Mg, and also Ca and Cu in women. In men, serum Cu was positively correlated with Mg and Ca concentrations. In patients from group 1 (NYHA I–II), Mg content was positively correlated with Ca and Cu. In this patient group, Ca was also positively associated with Cu content in serum. In group 2 (NYHA III-IV), serum Mg concentration was significantly positively correlated with that of Cu and Ca.

Conclusions

Changes in the serum concentrations of macro-and microminerals may significantly affect the severity of HF in Polish patients.

The Role of Zinc in Copper Homeostasis of Aspergillus fumigatus

Copper is an essential metal ion that performs many physiological functions in living organisms. Deletion of Afmac1, which is a copper-responsive transcriptional activator in A. fumigatus, results in a growth defect on aspergillus minimal medium (AMM). Interestingly, we found that zinc starvation suppressed the growth defect of the Δafmac1 strain on AMM. In addition, the growth defect of the Δafmac1 strain was recovered by copper supplementation or introduction of the CtrC gene into the Δafmac1 strain. However, chelation of copper by addition of BCS to AMM failed to recover the growth defect of the Δafmac1 strain. Through Northern blot analysis, we found that zinc starvation upregulated CtrC and CtrA2, which encode membrane copper transporters. Interestingly, we found that the conserved ZafA binding motif 5'-CAA(G)GGT-3' was present in the upstream region of CtrC and CtrA2 and that mutation of the binding motif led to failure of ZafA binding to the upstream region of CtrC and upregulation of CtrC expression under zinc starvation. Furthermore, the binding activity of ZafA to the upstream region of CtrC was inversely proportional to the zinc concentration, and copper inhibited the binding of ZafA to the upstream region of CtrC under a low zinc concentration. Taken together, these results suggest that ZafA upregulates copper metabolism by binding to the ZafA binding motif in the CtrC promoter region under low zinc concentration, thus regulating copper homeostasis. Furthermore, we found that copper and zinc interact in cells to maintain metal homeostasis.

Toxicological effect of zinc on liver of broiler chicks

Background

The objective of this study is to examine the toxic effects of zinc on the liver of broiler chicks. For this purpose, twenty broiler chicks were taken for the experiment and their weight ranging from 35-45 g. They were divided into four groups: one control and three treated groups. All treated groups were supplemented with 300 mg/kgb.w (low dose, LD), 600 mg/kgb.w (intermediate dose, ID) and 900 mg/kgb.w. (high dose, HD) of Zinc and the control group was fed basal commercial starter diet for 21 days.

Results

Necrosis, liver cell hypertrophy, fuzzy liver cells and lymphocytic inflammation were found in birds exposed to the low and intermediate dose as compared to the controlled group. Broiler chicks exposed to high dose showed pronounced changes in the liver such as congestion of blood vessels, connective tissue hyperplasia, bile duct proliferation, dilation of sinusoids, damaged intercellular contacts between hepatocytes, liver cell hypertrophy and accumulation of inflammatory cells

Conclusion

After the careful analysis of the study, the results have been reported that if one can take zinc in higher amount as supplements or in their foods than it affects the normal structure of the liver and it will alter the functioning of the liver in both human and animals.

Zinc transporter SLC39A11 polymorphisms are associated with chronic gastritis in the Korean population: the possible effect on spicy food intake

Herein, we hypothesized that ZIP11 variants would be important risk factors for chronic gastritis and that there would be an interaction effect of the relationship between their variants and spicy food intake on the development of chronic gastritis. Participants in this cross-sectional study (n = 3882 + 252) were recruited from a cohort of the Korean Genome and Epidemiology Study in 2001. Age, sex, education, smoking and drinking status, exercise, stress, and income level of all participants were determined by a questionnaire. Demographic and anthropometric data were collected. Fasting blood samples were collected to determine the serum levels of glucose, insulin, total bilirubin, total cholesterol, high-density lipoprotein cholesterol, and triglycerides. The presence of chronic gastritis was defined as a confirmed diagnosis by a physician. Food consumption was determined using a semiquantitative food frequency questionnaire. We found 8 different single nucleotide polymorphisms (SNPs) that are significantly different between subjects without gastritis and those with gastritis. Of these 8 SNPs, 3 SNP (rs17183225 [C/T], rs17780814 [A/C], and rs17780820 [A/G]) are closely located in the intronic region of zinc transporter SLC39A11, commonly known as ZIP11, and show linkage disequilibrium (D' = 1.0). We also found that participants with (TCA + TCG) haplotype of ZIP11 at high levels of dietary intake of spicy foods show a significantly increasing tendency in the odds of having chronic gastritis when compared with those with CAA haplotype (odds ratio, 2.620; 95% confidence interval, 1.207-5.689). The data indicate positive associations between higher meal frequency and lower spicy food preference and gastritis. In conclusion, we found that zinc transporter gene ZIP11 is associated with chronic gastritis in the Korean population and it may interact with spicy food, which suggests ZIP11 as a therapeutic target for precision nutrition.

Effects of copper and zinc on ischemic heart disease and myocardial infarction: a Mendelian randomization study

Background

Despite great progress in prevention and control, ischemic heart disease (IHD) remains a leading cause of global morbidity and mortality. Diet plays a key role in IHD, but a comprehensive delineation of the role of dietary factors in IHD is not yet quite complete.

Objective

The aim of this study was to test the long-standing hypothesis that copper is protective and zinc harmful in IHD.

Design

We used separate-sample instrumental variable analysis with genetic instruments (Mendelian randomization). We obtained single nucleotide polymorphisms (SNPs) from a genome wide association study, strongly (P value < 5 × 10-8) and independently associated with erythrocyte copper and zinc. We applied these genetic predictors of copper and zinc to the largest, most extensively genotyped IHD case (n ≤ 76014)-control (n ≤ 264785) study, based largely on CARDIoGRAMplusC4D 1000 Genomes and the UK Biobank SOFT CAD, to obtain SNP-specific Wald estimates for the effects of copper and zinc on IHD, which were combined through the use of inverse variance weighting. Sensitivity analysis included use of the MR-Egger method, and reanalysis including SNPs independently associated with erythrocyte copper and zinc at P value < 5 × 10-6.

Results

Genetically instrumented copper was negatively associated with IHD (OR: 0.94; 95% CI: 0.90, 0.98). Genetically instrumented zinc was positively associated with IHD (OR: 1.06; 95% CI: 1.02, 1.11). Sensitivity analysis via MR-Egger gave no indication of unknown pleiotropy; less strongly associated SNPs gave similar results for copper.

Conclusion

Genetic validation of a long-standing hypothesis suggests that further investigation of the effects, particularly of copper, on IHD may provide a practical means of reducing the leading cause of mortality and morbidity.

The Relationship between Serum Zinc Level and Heart Failure: A Meta-Analysis

Zinc is essential for the maintenance of normal cellular structure and functions. Zinc dyshomeostasis can lead to many diseases, such as cardiovascular disease. However, there are conflicting reports on the relationship between serum zinc levels and heart failure (HF). The purpose of the present study is to explore the relationship between serum zinc levels and HF by using a meta-analysis approach. PubMed, Web of Science, and OVID databases were searched for reports on the association between serum zinc levels and HF until June 2016. 12 reports with 1453 subjects from 27 case-control studies were chosen for the meta-analysis. Overall, the pooled analysis indicated that patients with HF had lower zinc levels than the control subjects. Further subgroup analysis stratified by different geographic locations also showed that HF patients had lower zinc levels than the control subjects. In addition, subgroup analysis stratified by HF subgroups found that patients with idiopathic dilated cardiomyopathy (IDCM) had lower zinc levels than the control subjects, except for patients with ischemic cardiomyopathy (ICM). In conclusion, the results of the meta-analysis indicate that there is a significant association between low serum zinc levels and HF.

Associations between Zinc Deficiency and Metabolic Abnormalities in Patients with Chronic Liver Disease

Zinc (Zn) is an essential trace element which has favorable antioxidant, anti-inflammatory, and apoptotic effects. The liver mainly plays a crucial role in maintaining systemic Zn homeostasis. Therefore, the occurrence of chronic liver diseases, such as chronic hepatitis, liver cirrhosis, or fatty liver, results in the impairment of Zn metabolism, and subsequently Zn deficiency. Zn deficiency causes plenty of metabolic abnormalities, including insulin resistance, hepatic steatosis and hepatic encephalopathy. Inversely, metabolic abnormalities like hypoalbuminemia in patients with liver cirrhosis often result in Zn deficiency. Recent studies have revealed the putative mechanisms by which Zn deficiency evokes a variety of metabolic abnormalities in chronic liver disease. Zn supplementation has shown beneficial effects on such metabolic abnormalities in experimental models and actual patients with chronic liver disease. This review summarizes the pathogenesis of metabolic abnormalities deriving from Zn deficiency and the favorable effects of Zn administration in patients with chronic liver disease. In addition, we also highlight the interactions between Zn and other trace elements, vitamins, amino acids, or hormones in such patients.

ATSDR evaluation of potential for human exposure to zinc

As part of its mandate, the Agency for Toxic Substances and Disease Registry (ATSDR) prepares toxicological profiles on hazardous chemicals found at Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) National Priorities List (NPL) sites that have the greatest public health impact. These profiles comprehensively summarize toxicological and environmental information. This article constitutes the release of portions of the toxicological profile for zinc. The primary purpose of this article is to provide interested individuals with environmental information on zinc that includes production data, environmental fate, potential for human exposure, analytical methods and a listing of regulations and advisories. Toxicology and Industrial Health 2007; 23: 247—308

ATSDR evaluation of the health effects of zinc and relevance to public health

As part of its mandate, the Agency for Toxic Substances and Disease Registry (ATSDR) prepares toxicological profiles on hazardous chemicals found at Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) National Priorities List (NPL) sites, which have the greatest public health impact. These profiles comprehensively summarise toxicological and environmental information. This article constitutes the release of portions of the Toxicological Profile for Zinc. The primary purpose of this article is to provide public health officials, physicians, toxicologists, and other interested individuals and groups with an overall perspective on the toxicology of zinc. It contains descriptions and evaluations of toxicological studies and epidemiological investigations, and provides conclusions, where possible, on the relevance of toxicity and toxicokinetic data to public health. Toxicology and Industrial Health 2006; 22: 423-493.

Dietary copper and human health: Current evidence and unresolved issues

Although copper (Cu) is recognized as an essential trace element, uncertainties remain regarding Cu reference values for humans, as illustrated by discrepancies between recommendations issued by different national authorities. This review examines human studies published since 1990 on relationships between Cu intake, Cu balance, biomarkers of Cu status, and health. It points out several gaps and unresolved issues which make it difficult to assess Cu requirements. Results from balance studies suggest that daily intakes below 0.8 mg/day lead to net Cu losses, while net gains are consistently observed above 2.4 mg/day. However, because of an incomplete collection of losses in all studies, a precise estimation of Cu requirements cannot be derived from available data. Data regarding the relationship between Cu intake and potential biomarkers are either too preliminary or inconclusive because of low specificity or low sensitivity to change in dietary Cu over a wide range of intakes. Results from observation and intervention studies do not support a link between Cu and a risk of cardiovascular disease, cognitive decline, arthritis or cancer for intakes ranging from 0.6 to 3mg/day, and limited evidence exists for impaired immune function in healthy subjects with a very low (0.38 mg/day) Cu intake. However, data from observation studies should be regarded with caution because of uncertainties regarding Cu concentration in various foods and water. Further studies that accurately evaluate Cu exposure based on reliable biomarkers of Cu status are needed.

Fluctuation of potential zinc status biomarkers throughout a reproductive cycle of primiparous and multiparous sows

Fluctuations in Zn metabolism throughout gestation and lactation might affect Zn requirements. However, scientific data on Zn requirements for breeding sows are limited. The objective of the present study was to assess the Zn status of primiparous and multiparous sows using different Zn status biomarkers, to identify periods of critical Zn status throughout the reproductive cycle at different parities. Blood samples were taken after overnight fasting before feeding in the morning from five primiparous and ten multiparous sows at fixed time intervals during gestation (days - 5, 0 (insemination), 21, 42, 63 and 84), around parturition (days 108, 112, 115 (parturition) and 118) and during lactation (days 122, 129 and 143 (weaning)). At parturition, blood samples were collected from two randomly selected piglets per sow before colostrum intake. Plasma was analysed for Zn and Cu contents, whereas serum was analysed for alkaline phosphatase, metallothionein and albumin concentrations. Independently of parity, all biomarkers fluctuated differently during gestation and lactation (P< 0·050). This reflects their different roles in Zn metabolism, and suggests that the choice of a Zn status biomarker necessitates careful consideration. Low average plasma Zn concentration at the end of gestation and throughout lactation seem to be replenished towards weaning.

The potential for zinc stable isotope techniques and modelling to determine optimal zinc supplementation

It is well recognised that zinc deficiency is a major global public health issue, particularly in young children in low-income countries with diarrhoea and environmental enteropathy. Zinc supplementation is regarded as a powerful tool to correct zinc deficiency as well as to treat a variety of physiologic and pathologic conditions. However, the dose and frequency of its use as well as the choice of zinc salt are not clearly defined regardless of whether it is used to treat a disease or correct a nutritional deficiency. We discuss the application of zinc stable isotope tracer techniques to assess zinc physiology, metabolism and homeostasis and how these can address knowledge gaps in zinc supplementation pharmacokinetics. This may help to resolve optimal dose, frequency, length of administration, timing of delivery to food intake and choice of zinc compound. It appears that long-term preventive supplementation can be administered much less frequently than daily but more research needs to be undertaken to better understand how best to intervene with zinc in children at risk of zinc deficiency. Stable isotope techniques, linked with saturation response and compartmental modelling, also have the potential to assist in the continued search for simple markers of zinc status in health, malnutrition and disease.

Deficient zinc levels and myocardial infarction : association between deficient zinc levels and myocardial infarction: a meta-analysis

The purpose of this study is to clarify the association between Zn levels and myocardial infarction (MI) using a meta-analysis approach. We searched articles in the PubMed, OVID, and ScienceDirect published as of November 2014. Thirteen eligible articles with 2886 subjects from 41 case-control studies were identified. Overall, pooled analysis indicated that subjects with MI had lower Zn levels than healthy controls (standardized mean difference (SMD) = -1.848, 95 % confidence interval (CI) = [-2.365, -1.331]). Further subgroup analysis found that subjects with MI had lower Zn levels than healthy controls in serum (SMD = -1.764, 95 % CI = [-2.417, -1.112]) and hair (SMD = -3.326, 95 % CI = [-4.616, -2.036]), but not in toenail (SMD = -0.396, 95 % CI = [-1.114, 0.322]). The subgroup analysis stratified by type of Zn measurement found a similar pattern in inductively coupled plasma-atomic absorption spectrometry (ICP-AAS) (SMD = -2.442, 95 % CI = [-3.092, -1.753]), but not in neutron activation analysis (NAA) (SMD = -0.449, 95 % CI = [-1.127, 0.230]). Lower Zn levels in MI patients were found both in male (SMD = -3.350, 95 % CI = [-4.531, -2.169]) and female (SMD = -2.681, 95 % CI = [-3.440, -1.922]). And the difference of Zn levels according to MI in Asia (SMD = -2.555, 95 % CI = [-3.267, -1.844]) was greater to that among the population in Europe (SMD = -0.745, 95 % CI = [-1.386, -0.104]), but no difference was found in Oceania (SMD = -0.255, 95 % CI = [-0.600, 0.089]). In conclusion, this meta-analysis indicates that there is a significant association between Zn deficiency and MI. We suggest that a community-based, long-term observation in a cohort design should be performed to obtain better understanding of causal relationships between Zn and MI, through measuring hair Zn at baseline to investigate whether the highest zinc category versus lowest was associated with MI risk.

Association between copper levels and myocardial infarction: a meta-analysis

BACKGROUND AND AIMS

There are conflicting reports as to the correlation between copper (Cu) levels and myocardial infarction (MI). The purpose of the present study is to clarify the association between Cu levels and MI.

METHODS

We searched articles in Pubmed and the Chinese Journal Full-text Database published as of October 2014. A meta-analysis was used to pool estimates of the standardized mean difference (SMD) with 95% confidence interval (CI).

RESULTS

Pooled analysis indicated that subjects with MI had higher serum Cu levels than healthy controls (SMD = 1.629, 95%CI = [1.027, 2.232], Z = 5.30, p < 0.001). Further subgroup analysis stratified by ethnicity indicated that subjects with MI had higher serum Cu levels than healthy controls among members of the Asian race (SMD = 2.191, 95%CI = [1.401, 2.981], Z = 5.43, p < 0.001), but not among members of the Caucasian race (SMD = 0.411, 95%CI = [-0.030, 0.851], Z = 1.83, p = 0.068). The results obtained from hairs showed no association between MI and hair Cu levels (SMD = 0.338, 95% CI = [-0.171, 0.848], Z = 1.30, p = 0.193). But the subgroup analysis stratified by geological location indicated that subjects with MI had higher hair Cu levels than healthy controls in Pakistan (SMD = 0.785, 95% CI = [0.587, 0.983], Z = 10.29, p < 0.001), but not in India (SMD = -9.028, 95% CI = [-10.747, -7.309], Z = 7.77, p < 0.001).

CONCLUSION

This meta-analysis indicates a significant association between high serum Cu levels and MI. However, the subgroup analysis found that there was significant effect modification of Cu levels by ethnicity. Thus, we suggest that a trans-regional multicenter study is needed to obtain better understanding of causal relationships between Cu and MI in different human races.

Spatial memory deficits in a mouse model of late-onset Alzheimer's disease are caused by zinc supplementation and correlate with amyloid-beta levels

Much of the research in Alzheimer’s disease (AD) that uses mouse models focuses on the early-onset form of the disease, which accounts for less than 5% of cases. In contrast, this study used a late-onset AD model to examine the interaction between increased dietary zinc (Zn) and the apolipoprotein E (ApoE) gene. ApoE ε4 is overrepresented in late-onset AD and enhances Zn binding to amyloid-β (Aβ). This study sought to determine if elevated dietary Zn would impair spatial memory in CRND8 mice (CRND8), as well as mice who carry both the mutated human amyloid precursor protein (APP) and ApoE ε4 genes (CRND8/E4). Mice were provided with either lab tap water or water enhanced with 10 ppm Zn (ZnCO₃) for 4 months. At 6 months of age, spatial memory was measured by the Barnes maze. CRND8 mice exhibited significant memory deficits compared to WT mice, as shown by an increased latency to reach the escape box. For the CRND8/E4, but not the CRND8 mice, those given Zn water made significantly more errors than those on lab water. During the probe trial for the WT group, those on Zn water spent significantly less time in the target quadrant than those on lab water. These data suggest that increased dietary Zn can significantly impair spatial memory in CRND8/E4. WT mice given Zn water were also impaired on the 24-h probe trial when compared to lab water WTs. Within the CRND8/E4 group only, levels of soluble Aβ were significantly correlated with average primary latencies. Within the Zn-treated CRND8/E4 group, there was a significant correlation between insoluble Aβ and average primary errors. Levels of the zinc transporter 3, ZnT3, were negatively correlated with soluble Aβ (p < 0.01). These findings are particularly relevant because increased intake of dietary supplements, such as Zn, are common in the elderly—a population already at risk for AD. Given the effects observed in the CRND8/E4 mice, ApoE status should be taken into consideration when evaluating the efficacy of therapies targeting metals.

Alteration of plasma trace elements in patients undergoing open heart surgery

Trace elements may contribute to myocardial dysfunction and susceptibility of the phospholipid cell membrane to free-radical damage and oxidative changes. We studied the concentration of trace elements copper, zinc, and magnesium in cardiac surgery. Fifty-four consecutive patients for elective coronary artery bypass grafting (n = 30) and valve replacement (n = 24) were studied. Blood samples were collected every 30 min (T1-T5) during cardiopulmonary bypass and postoperatively (T6-T9). Plasma concentrations of copper, zinc, and magnesium were measured with flame atomic absorption spectrophotometry. The concentrations of copper, zinc, and magnesium were significantly different during and after cardiopulmonary bypass (p < 0.01). The zinc concentration at T7 and T8 (p < 0.01) and the copper concentration at T1, T9 (p < 0.05) were significantly different between two groups. However, the magnesium concentration had no significant differences between the two groups (p > 0.05). In patients undergoing valve replacement or coronary artery bypass grafting, the concentrations of copper and zinc decreased significantly during cardiopulmonary bypass. Our study suggests that the current cardiopulmonary bypass protocol is adequate in the maintenance of c magnesium. However, the low copper and zinc concentrations found in the present study may suggest that in the future, supplementation particularly of copper and zinc may become a necessary procedure in cardiac surgery with cardiopulmonary bypass.

Relation between zinc, copper, and magnesium concentrations following cardiopulmonary bypass and postoperative atrial fibrillation in patients undergoing coronary artery bypass grafting

Atrial fibrillation is the most frequently encountered arrhythmia following cardiac surgery. Since the essential trace elements zinc, copper, and magnesium are suspected to have an effect on postoperative atrial fibrillation, the concentrations of these elements were determined by flame atomic absorption spectrophotometry in the plasma of 60 patients undergoing elective coronary artery bypass grafting. Blood samples were collected every 30 min during cardiopulmonary bypass and postoperatively. Plasma concentrations of copper, zinc, and magnesium were measured with flame atomic absorption spectrophotometry. All patients were monitored by continuous electrocardiography until they became outpatients or immediately after atrial fibrillation had taken place. Atrial fibrillation occurred in 13 of the 60 patients, corresponding to 21.7%. The zinc and copper concentrations at postoperative days 1 and 3 were significantly different (P < 0.05) between patients with and without atrial fibrillation. The concentrations of zinc following cardiopulmonary bypass recovered more slowly in patients with postoperative atrial fibrillation than in patients without it. Whether or not supplemental zinc could lower the incidence of postoperative atrial fibrillation should be evaluated in future prospective randomized clinical trials.

Zinc and copper levels in severe heart failure and the effects of atrial fibrillation on the zinc and copper status

Oxidative stress is involved in the pathogenesis of congestive heart failure (CHF). Some trace elements serve as antioxidant defenses. The purpose of this study was to analyze the effect of atrial fibrillation (AF) on zinc (Zn) and copper (Cu) levels in patients with advanced CHF. In this prospective study, serum Zn and Cu levels in 78 patients with clinically advanced CHF, i.e., New York Heart Association (NYHA) functional class III or IV (40 patients with AF and 38 in sinus rhythm) were measured using atomic absorption spectrophotometry. All patients also had a left ventricular ejection fraction (EF) of <35%. We recruited 40 volunteers with nearly the same age and weight as control. They had normal EF. There was no significant difference between patients with AF and those with sinus rhythm regarding serum Zn and Cu levels. However, both groups showed significant hypozincemia (p < 0.000) and a decreased Zn/Cu ratio (p < 0.03) compared with control group. Serum Cu levels were similar in the two groups and did not differ significantly from the control group. In patients with advanced CHF, irrespective of the rhythm, profound hypozincemia, and a decreased Zn/Cu ratio were present, which could be secondary to the activation of the renin-angiotensin-aldosterone system and CHF medications. The results suggest the need for more studies focusing on possible benefits with Zn nutriceutical replacement in patients with advanced CHF.

A review of select vitamins and minerals used by postmenopausal women

OBJECTIVES

The purpose of this review is to summarize the effectiveness of select vitamins, minerals and trace elements in postmenopausal women for their effects on bone health, cardiovascular health, breast cancer, cognition and vasomotor symptoms.

METHODS

Review of the relevant literature and results from recent clinical studies, as well as critical analyses of published systematic reviews and meta-analyses were obtained from PubMed and Cochrane Library of Reviews. Vitamin A, the B vitamins, vitamin C, calcium, vitamin D, vitamin E, vitamin K, magnesium, selenium and zinc were selected for review. In circumstances where the vitamin, mineral or trace element has not been studied for a given condition, no information was provided.

RESULTS AND DISCUSSION

All vitamins, minerals and trace elements play an important role in maintaining health and wellbeing among menopausal women. Adequate dietary intake is essential and supplementation should be considered in women with documented malabsorption syndromes or deficiencies. Based on a review of the literature, supplementation with vitamin C, D, K and calcium can also be recommended for proper maintenance of bone health. The only supplement studied for vasomotor symptoms was vitamin E and this vitamin lacked clinical support. Supplementation in healthy postmenopausal women with vitamins and minerals in diet or pill forms cannot be recommended currently for any other indications.

Daily dietary intake of iron, copper, zinc and manganese in a Spanish population

To evaluate the daily dietary intake of essential metals in the Canary Islands, the iron, copper, zinc and manganese contents in 420 food and drink samples collected in local markets were analysed by inductively coupled plasma-atomic emission spectrometry (ICP-AES). The estimated daily dietary intakes of iron, copper, zinc and manganese are 13.161 mg/day, 2.098 mg/day, 8.954 mg/day and 2.372 mg/day, respectively. The iron dietary intake was found to be below the recommendations fixed for adult women, while the copper and manganese dietary intakes fulfilled the Recommended Dietary Allowances. The mean daily intake of zinc was below the Recommended Dietary Allowance. Cereals were found to be the food group that contributed most to the intake of these metals. While the island of El-Hierro presented iron, copper, zinc and manganese mean intakes over the estimated intakes for the whole archipelago, Fuerteventura island showed the lowest intakes. Tenerife and Fuerteventura showed the lowest iron intakes, being below the recommendations.

Metal-specific risk assessment--the European perspective

This review considers the development of the regulatory process for metals in the European Union (Regulation for Registration, Evaluation, Authorisation and Restriction of Chemicals, REACH). The manner in which the REACH process was developed, its history, and the relative involvement of government and industry are examined. The problems involved in setting up the system and the steps in optimisation are considered. One of the major difficulties in the development of the REACH mechanism was incorporating the fact that many metals are essential elements, which is not a factor that most toxicological examinations consider. How the REACH process evolved to deal with these problems and how the mechanisms were put in place to overcome them is examined. Looking specifically at examples of industry working with academia, one needs to consider how a risk assessment can be developed and submitted in a timely and successful fashion.

Overview of health risk assessments for zinc

Zinc is an essential trace mineral nutrient required for growth and reproduction in man and other living organisms. Zinc deficiency has been identified as global public health issue that significantly impacts developing countries; as a result, zinc essentiality and the impacts of deficiency have been extensively studied. Zinc is also widely used in commercial products and is a high-production-volume industrial metal. This has provided opportunities for human exposure and prompted multiple assessments of adverse health impacts that might result from exposure excess. Zinc thus provides an illustrative case study of the methodological contrasts between nutritional and toxicological evaluations and highlights the need for risk assessment guidelines that may be tailored to accommodate the properties of essential trace elements.

Taste acuity in response to zinc supplementation in older Europeans

Taste acuity declines with age and may be dependent upon Zn status. The aim of the present double-blind, randomised controlled intervention trial has been to determine taste acuity in response to Zn supplementation (placebo, or 15 or 30 mg Zn/d). Healthy older European adults aged 70–87 years were recruited within Italy (Rome) (n 108) and France (Grenoble) (n 91) to the European Commission-funded Zenith project. A signal detection theory approach was adopted for taste assessment. The data were converted to R indices and analysed by repeated-measures ANOVA controlling for baseline taste acuity as well as serum and erythrocyte Zn. Serum Zn increased post-intervention, indicating compliance with the intervention. Results differed across geographical region. Salt taste acuity was greater in response to Zn (30 mg) than placebo post-intervention among those recruited in Grenoble. There was no apparent change in acuity for sweet, sour or bitter taste in response to Zn. Supplemented Zn may have potential to enhance salt taste acuity in those over the age of 70 years. Further research is required to determine if enhanced salt taste acuity is reflected in the eating experiences of older individuals.

Copper and human health: biochemistry, genetics, and strategies for modeling dose-response relationships

Copper (Cu) and its alloys are used extensively in domestic and industrial applications. Cu is also an essential element in mammalian nutrition. Since both copper deficiency and copper excess produce adverse health effects, the dose-response curve is U-shaped, although the precise form has not yet been well characterized. Many animal and human studies were conducted on copper to provide a rich database from which data suitable for modeling the dose-response relationship for copper may be extracted. Possible dose-response modeling strategies are considered in this review, including those based on the benchmark dose and categorical regression. The usefulness of biologically based dose-response modeling techniques in understanding copper toxicity was difficult to assess at this time since the mechanisms underlying copper-induced toxicity have yet to be fully elucidated. A dose-response modeling strategy for copper toxicity was proposed associated with both deficiency and excess. This modeling strategy was applied to multiple studies of copper-induced toxicity, standardized with respect to severity of adverse health outcomes and selected on the basis of criteria reflecting the quality and relevance of individual studies. The use of a comprehensive database on copper-induced toxicity is essential for dose-response modeling since there is insufficient information in any single study to adequately characterize copper dose-response relationships. The dose-response modeling strategy envisioned here is designed to determine whether the existing toxicity data for copper excess or deficiency may be effectively utilized in defining the limits of the homeostatic range in humans and other species. By considering alternative techniques for determining a point of departure and low-dose extrapolation (including categorical regression, the benchmark dose, and identification of observed no-effect levels) this strategy will identify which techniques are most suitable for this purpose. This analysis also serves to identify areas in which additional data are needed to better define the characteristics of dose-response relationships for copper-induced toxicity in relation to excess or deficiency.

Zinc and copper metabolism in pregnancy and lactation of adolescent women

OBJECTIVE

Pregnant and lactating adolescent women are at risk of zinc and copper deficiency but their capacity for metabolic adaptation is poorly known. This study investigated the effect of pregnancy and lactation on zinc and copper metabolism in adolescent women by comparing biochemical indices between groups in different reproductive states.

METHODS

Habitual dietary intake and biochemical indices (zinc, copper, alkaline phosphatase, and ceruloplasmin in plasma; zinc [E-Zn], metallothionein [E-MT], and superoxide dismutase [E-SOD] in erythrocytes) and their relation were compared among non-pregnant non-lactating adolescents (NPNLs; n = 26), third-trimester pregnant adolescents (PAs; n = 26), and lactating adolescents up to 3 mo postpartum (LAs; n = 21).

RESULTS

Zinc and copper intakes were not different across groups (on average, 8.7 and 1.0 mg/d, respectively). PAs had lower plasma zinc but higher plasma copper, alkaline phosphatase, and ceruloplasmin levels than did LAs and NPNLs (P < 0.05). E-SOD and E-Zn were similar in all groups but E-MT was higher in the PA and LA groups than in the NPNL group (P < 0.05). Correlations between plasma copper and ceruloplasmin and between E-MT and E-Zn were observed in the LA and NPNL groups (r > or = 0.64, P < 0.01) but not in the PA group. In contrast, correlations between plasma alkaline phosphatase and plasma zinc, between E-MT and plasma zinc, and between E-SOD and E-Zn were observed only in the PA group (r > or = 0.46, P < 0.05).

CONCLUSION

Zinc and copper biochemical responses to pregnancy and lactation in the adolescent women studied appeared qualitatively similar to those described in previous studies in adult women. However, the significant correlations observed between the activity of zinc-dependent enzymes and plasma (or erythrocyte) zinc suggest that a poor maternal zinc status may limit the metabolic adaptation capacity of these adolescent women especially during pregnancy.

The Effect of Zinc Supplementation in Humans on Plasma Lipids, Antioxidant Status and Thrombogenesis

The potential exists for zinc to influence numerous metabolic functions and to impact a range of diseases. In the present review we examine the reported relationships between zinc and plasma lipids, haemostasis and other factors postulated to play a role in atherogenesis. Ecological studies that investigated zinc intake or status, and incidence of coronary heart disease (CHD) reveal no consistent pattern. The conflicting observations may be explained by differences in the extent of CHD, site of atherosclerosis, or confounding factors. In most studies the diurnal variation in serum zinc concentrations, and the lifestyle factors that affect cholesterol metabolism were not explicitly considered. Results of randomised controlled trials show that low-density lipoprotein (LDL) oxidation and the concentrations of LDL-cholesterol (c), total cholesterol and triglycerides in plasma are unaffected by supplementation with up to 150 mg Zn/d. In contrast, plasma high-density lipoprotein (HDL)-c concentrations decline when zinc supplements provide a dose >50 mg/d. Limited data suggest that sustained hyperzincaemia predisposes individuals to thrombogenesis, whereas acute zinc depletion impairs platelet aggregation and prolongs bleeding time. In addition, Zinc supplements have been shown in some studies to decrease Cu/Zn-superoxide dismutase activity, primarily due to the antagonistic relationship between high zinc intakes and copper absorption. Besides the demonstrated adverse effect of zinc supplementation on plasma HDL-c concentrations in apparently healthy men, there is insufficient evidence to determine the role of zinc supplementation in influencing other risk factors for CHD such as antioxidant status and thrombogenesis.

A moderately high intake compared to a low intake of zinc depresses magnesium balance and alters indices of bone turnover in postmenopausal women

OBJECTIVES

To determine whether moderately high or low intakes of zinc adversely affect the copper status of postmenopausal women to result in unfavorable changes in calcium and magnesium metabolism and other indicators of bone turnover.

DESIGN

After a 10-day equilibration period in which the diet provided 31.5 micromol (2 mg) Cu and 137.7 micromol (9 mg) Zn/8.4 MJ (2000 kcal), the subjects were randomly divided into two groups, with one group fed the basal diet supplemented to provide 15.7 micromol (1 mg) Cu/8.4 MJ, and the other group fed the same diet supplemented to provide 47.2 micromol (3 mg) Cu/8.4 MJ. After equilibration, both groups were fed the basal diet with no zinc supplemented (provided 45.9 micromol [3 mg] Zn/8.4 MJ) for 90 days; this was followed by another 10-day equilibration period before the basal diet was supplemented with zinc to provide 811 micromol (53 mg)/8.4 MJ for 90 days.

SETTING

The metabolic unit of the Grand Forks Human Nutrition Research Center, Grand Forks, ND, USA.

SUBJECTS

A total of 28 postmenopausal women recruited by advertisement throughout the United States of America. Among them, 25 women (64.9+6.7 y) completed the study; 21 as designed.

RESULTS

The moderately high intake compared to the low intake of zinc increased the excretion of magnesium in the feces and urine, which resulted in a decreased magnesium balance. In the women fed low dietary copper, plasma osteocalcin was higher during the low-zinc than high-zinc dietary period. The urinary excretion of N-telopeptides was increased and the serum calcitonin concentration was decreased by high dietary zinc regardless of dietary copper.

CONCLUSIONS

A moderately high intake of zinc (811 micromol/day; 53 mg/day) did not induce changes in copper metabolism that resulted in unfavorable changes in bone or mineral metabolism. However, low dietary zinc (45.9 micromol/day; 3 mg/day) apparently resulted in undesirable changes in circulating calcitonin and osteocalcin. As a moderately high intake of zinc decreased magnesium balance, further study of the possibility that a high intake of zinc is a health concern for individuals consuming less than the recommended amounts of magnesium is warranted.

Zinc supplementation for four months does not affect plasma copper concentration in infants

AIM

The aim of the present study, which was undertaken as a sub-study within a randomized controlled trial of zinc supplementation, was to evaluate the effect of prolonged zinc supplementation on copper status as assessed by hematological markers.

METHODS

Plasma copper and zinc were estimated at baseline and after 120 d of supplementation in a randomly selected infant subset (115) of the children. Of these, 61 children were in a zinc group (Z) getting 10 mg of elemental zinc, and 54 were in a control group (C) getting supplement without zinc.

RESULTS

Baseline plasma zinc was comparable in the two groups; post-supplementation zinc was significantly higher (Z 93.0 +/- 3.6 vs C 60.6 +/- 8.0) in the zinc supplementation group. There was no significant difference in the mean/median copper levels between the zinc and control groups. The percentage of children with plasma copper <100 microg/dl was also not significantly different between groups (baseline Z 14.8%, C 11.1%; post-supplementation Z 18.0%, C 11.1%). There were no differences between the zinc and control groups after 120 d of supplementation in hemoglobin (Hgb), mean corpuscular volume (MCV), mean corpuscular hemoglobin concentration (MCHC), or number of lymphocytes or granulocytes.

CONCLUSION

Zinc supplementation of 10 mg/d for 4 mo in this study did not affect copper status, as assessed by plasma copper concentration and hematological parameters, diagnostics of copper deficiency.

Copper enzyme activities in cystic fibrosis before and after copper supplementation plus or minus zinc

One laboratory reports low activities for 2 blood copper enzymes in subjects with cystic fibrosis (CF), which suggests that moderate copper deficiency is common in this state. The present study attempted to confirm this proposition in 3 ways: repeat the measures for 1 of the 2 copper enzymes (superoxide dismutase) in a new group of CF patients (males and females, N = 38), add another copper enzyme measure (plasma diamine oxidase) that has high sensitivity to copper status, and test if copper enzyme activities in CF patients rise by copper supplementation. The last test was performed plus or minus zinc supplementation since poor zinc status may contribute to poor copper status. The results for the first 2 aims supported the idea of poor copper status, as low activities were found for CF subjects for 2 copper enzyme activities, erythrocyte superoxide dismutase and plasma diamine oxidase (although normal activities were obtained for another copper enzyme, plasma ceruloplasmin, both as U/mL plasma or U/mg ceruloplasmin immunoreactive protein). For the last aim, copper enzyme activities were not altered by copper supplementation (6 weeks, 3 mg copper/d as copper-glycinate), plus or minus concurrent zinc supplementation (30 mg zinc/d as zinc-glycinate). Therefore, CF may cause a tendency to moderate copper deficiency, which may be due to abnormal copper metabolism not easily corrected by increased copper and/or zinc intake.

Some magnesium status indicators and oxidative metabolism responses to low-dietary magnesium are affected by dietary copper in postmenopausal women

OBJECTIVE

A study with human volunteers was conducted to ascertain whether a low intake of copper (Cu) would exacerbate the response to a deficient intake of magnesium (Mg).

METHODS

Nineteen postmenopausal women, age 47 to 78 y, completed a metabolic unit study as designed. For 162 d, nine women were fed a diet containing 1.0 mg of Cu/2000 kcal and 10 women were fed 3.0 mg of Cu/2000 kcal. Diets contained 99 or 399 mg of Mg/2000 kcal for 81 d in a randomized, double-blind, crossover design. Differences were considered significant when statistical analysis yielded P </= 0.05.

RESULTS

Magnesium balance was highly positive when the dietary magnesium was high but non-positive when dietary magnesium was low. Copper balance was more positive when dietary copper was high than when it was low. Plasma ionized magnesium was decreased by magnesium deprivation. Several variables measured indicated that low dietary copper affected the response to magnesium deprivation or vice-versa. Red blood cell magnesium was lower when dietary copper was low than when it was high. When dietary magnesium was low, serum copper was lower in the women fed marginal copper than in those fed luxuriant copper. When dietary magnesium was high, low dietary copper did not affect serum copper. Magnesium deprivation decreased red blood cell superoxide dismutase when dietary copper was luxuriant; when dietary copper was low, magnesium deprivation did not have much of an effect. Apolipoprotein A1 was lowest when dietary magnesium and copper were low. The order in which the magnesium restriction occurred affected the response of a number of variables to this treatment including concentrations of serum magnesium and total and low-density lipoprotein cholesterol.

CONCLUSIONS

The findings indicated that, in short-term magnesium depletion experiments, the response to depletion can be influenced by other dietary factors including copper intake and a high magnesium intake before depletion, and that 100 mg of Mg/d is inadequate for postmenopausal women.

Marginal maternal Zn intake in rats alters mammary gland Cu transporter levels and milk Cu concentration and affects neonatal Cu metabolism

Marginal zinc intake is common and leaves women particularly vulnerable to Zn deficiency due to increased demand for Zn as a consequence of reproduction. Zn deficiency during pregnancy and lactation has been associated with secondary affects on copper metabolism in the offspring; however, the underlying mechanisms are unknown. The effects of marginal maternal Zn intake on maternal and neonatal Cu metabolism were determined in rats. Plasma, milk and tissue Cu and Zn concentrations and plasma and milk ceruloplasmin (Cp) activity were measured in dams fed a control (CON, 25 mg Zn/kg diet) or a marginal Zn diet (ZD, 10 mg Zn/kg diet) and their suckling pups. There was no effect on maternal tissue Cu or Zn or milk Zn concentration; however, plasma Cp activity was higher in dams fed ZD, suggesting that Cp activity may be a useful marker for identifying marginal Zn status. Rats fed ZD had high mammary gland Ctr1, Atp7A and Atp7B levels, milk Cp activity and Cu concentration. Immunostaining and differential centrifugation indicated that ZD also altered Ctr1 and Atp7A localization in the mammary gland. Pups from dams fed ZD had higher small intestine Cu and lower plasma Cu than CON pups. These results suggest that marginal maternal Zn intake during pregnancy and lactation increase mammary gland Cu transporter levels and alter their localization, resulting in high milk Cu levels, possibly in response to transiently elevated plasma Cu levels. The combination of high milk Cu concentration and immature neonatal Cu transport exposes the suckling neonate to excess Cu; however, whether this occurs in humans is not yet known.

Zinc takes the center stage: its paradoxical role in Alzheimer's disease

There is compelling evidence that the etiology of Alzheimer's disease (AD) involves characteristic amyloid-beta (Abeta) deposition, oxidative stress, and anomalous metal-Abeta protein interaction. New studies have implicated redox active metals such as copper, iron, and zinc as key mediating factors in the pathophysiology of Alzheimer's disease. There is also evidence that drugs with metal chelating properties could produce a significant reversal of amyloid-beta plaque deposition in vitro and in vivo. This paper reviews current observations on the etiologic role of zinc in AD. We also discuss the interactions of zinc and copper with Abeta, a factor that purportedly facilitates disease processes. Finally, we review the protective role of zinc against Abeta cytotoxicity and hypothesize how the apparent effect of zinc on AD pathology may be paradoxical, The Zinc Paradox. Indeed, complex pathologic stressors inherent to the Alzheimer's diseased brain dictate whether or not zinc will be neuroprotective or neurodegenerative. Further research on the zinc paradox in AD is needed in order to elucidate the exact role zinc plays in AD pathogenesis.