Baseline Plasma Zinc and Risk of First Stroke in Hypertensive Patients

Association between serum copper levels and stroke in the general population: A nationally representative study

OBJECTIVES

The objective was to explore the association between serum copper levels and the prevalence of stroke.

METHODS

Data were obtained from 3 consecutive National Health and Nutrition Examination Survey (NHANES) cycles (2011-2016). Weighted multivariable logistic regression analysis was conducted to evaluate the association between serum copper levels and self-reported stroke.

RESULTS

A total of 5,151 adults met the inclusion criteria. A total of 181 (3.51%) stroke patients were identified. In comparison to individuals with serum copper levels in the lowest tertile (<16.4 µmol/l), those with levels in the middle tertile (16.4-19.8 µmol/l) had an odds ratio (OR) of 0.99 (95% confidence interval [CI]: 0.44-2.25), while those with levels in the highest tertile (>19.8 µmol/l) had an OR of 2.36 (95% CI: 1.01-5.52). Furthermore, each standard deviation (SD) increase in serum copper was found to be positively associated with the prevalence of stroke, with an OR of 1.44 (95% CI: 1.11-1.86). Dose‒response analysis showed a positive linear association between serum copper levels and stroke (Pnonlinearity=0.554).

CONCLUSIONS

This cross-sectional study suggested a positive association between serum copper levels and stroke among American adults.

Serum copper levels and risk of major adverse cardiovascular events: a systematic review and meta-analysis

Background

Despite the fact that several studies have investigated the association between serum copper levels (S-Cu) and the risk of cardiovascular diseases, this relationship remains unclear. The aims of this study were to investigate the association between S-Cu and risk of major adverse cardiovascular events (MACE), including total stroke, ischemic stroke, hemorrhagic stroke, myocardial infarction and cardiovascular mortality, and identify potential sources of results heterogeneity.

Methods

We carried out a systematic review and meta-analysis. The selection criteria were: (1) Observational studies (cohort studies, case-control studies and hybrid studies); (2) Studies containing quantitative data about the relationship between S-Cu and risk of MACE; (3) Estimating association measures; and (4) Studies written in English, French or Spanish. Overall pooled Odds ratio (pOR) and 95% confidence intervals (95% CI) of MACE for the highest vs. lowest S-Cu category were calculated using random-effects models.

Results

Sixteen studies with a total of 41,322 participants were included in the meta-analysis: 10 prospective cohort studies, 5 nested case-control studies and 1 case-control study. Comparing highest vs. lowest category, high S-Cu levels were associated with total stroke (pOR: 1.49, 95% CI 1.22-1.82; I² = 0%, p = 0.54), myocardial infarction (pOR: 1.31, 95% CI 1.17-1.46; I² = 0.0%, p = 0.92) and cardiovascular mortality (pOR: 1.60, 95% CI 1.39-1.86; I² = 0.0%, p = 0.54). Subgroup analysis showed that studies with a hybrid design had higher risks for cardiovascular mortality (pOR: 3.42, 95% CI 1.98-5.92) and ischemic stroke (pOR: 1.54, 95% CI 1.30-1.83).

Conclusion

High S-Cu levels were associated with an increased risk of total stroke, myocardial infarction and cardiovascular mortality. Hybrid studies seems to modify the strength of the association between S-Cu and the risk of cardiovascular mortality and ischemic stroke.

Systematic review registration

[https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022370782], identifier [CRD42022370782].

The Important Role of Zinc in Neurological Diseases

Zinc is one of the most abundant metal ions in the central nervous system (CNS), where it plays a crucial role in both physiological and pathological brain functions. Zinc promotes antioxidant effects, neurogenesis, and immune system responses. From neonatal brain development to the preservation and control of adult brain function, zinc is a vital homeostatic component of the CNS. Molecularly, zinc regulates gene expression with transcription factors and activates dozens of enzymes involved in neuronal metabolism. During development and in adulthood, zinc acts as a regulator of synaptic activity and neuronal plasticity at the cellular level. There are several neurological diseases that may be affected by changes in zinc status, and these include stroke, neurodegenerative diseases, traumatic brain injuries, and depression. Accordingly, zinc deficiency may result in declines in cognition and learning and an increase in oxidative stress, while zinc accumulation may lead to neurotoxicity and neuronal cell death. In this review, we explore the mechanisms of brain zinc balance, the role of zinc in neurological diseases, and strategies affecting zinc for the prevention and treatment of these diseases.

Contribution of heavy metals in PM2.5 to cardiovascular disease mortality risk, a case study in Guangzhou, China

Heavy metals play an important role in inducing fine particulate matter (PM_2.5) related cardiovascular disease (CVD). However, most of the past researches concerned the associations between CVD mortality and the PM_2.5 mass, which may not reveal the CVD mortality risk contributed by heavy metals in PM_2.5. This study explored the correlations between individual heavy metals in PM_2.5 and CVD mortality, identified the heavy metals that significantly contribute to PM_2.5-related CVD, heart disease (HD), and cerebrovascular disease (CEV) mortality, and attempted to establish corresponding source control measures. Over a 2-year study period, PM_2.5 was sampled daily in Guangzhou, China and analyzed for heavy metals. The airborne pollution and weather data, along with CVD, HD, and CEV mortality, were obtained at the same time. The excess risk (ER) of mortality was linked to the individual heavy metals using a distributed lag non-linear model. PM_2.5 and most heavy metals showed significant correlations with the CVD, HD, and CEV mortality; the largest cumulative ER (LCER) values of CVD mortality associated with an interquartile range increase in the levels of lead, cadmium, arsenic, selenium, antimony, nickel, thallium, aluminum, iron, and PM_2.5 were 2.43%, 2.23%, 1.66%, 2.39%, 1.19%, 1.21%, 2.69%, 3.29%, 1.74%, and 2.40%, respectively. Most heavy metals showed comparable LCER values of HD and CEV mortality. Heavy metals with the addition of PM_2.5 were divided into three groups following their LCER values; lead, cadmium, arsenic, antimony, thallium, zinc, aluminum, and iron, whose contributions were greater than or equal to the average effect of the PM_2.5 components, should be limited on a priority basis. These findings indicated that heavy metals play roles in the CVD, HD, and CEV mortality risk of PM_2.5, and specific control measures which aimed at the emission sources should be taken to reduce the CVD mortality risk of PM_2.5.

Environmental toxic metal contaminants and risk of stroke: a systematic review and meta-analysis

The relationship between toxic metals in the environment and clinical stroke risk remains unclear, although their role as immunotoxicants and carcinogens has been well established. We conducted a systematic review of the relationship between five metals (arsenic, mercury, copper, cadmium, and lead) and stroke. First, we comprehensively searched 3 databases (Pubmed, EMBASE, and Cochrane) from inception until June 2021. Random-effects meta-analyses, pooled relative risks (RR) and 95% confidence intervals (CI) were applied to evaluate the effect value. We finally identified 38 studies involving 642,014 non-overlapping participants. Comparing the highest vs. lowest baseline levels, chronic exposure to lead (RR = 1.07; 95%CI,1.00-1.14), cadmium (RR = 1.30; 95%CI,1.13-1.48), and copper (RR = 1.19; 95%CI,1.04-1.36) were significantly associated with stroke risks. However, the other two metals (arsenic and mercury) had less effect on stroke risk. Further analysis indicated that the association was likely in a metal dose-dependent manner. The results may further support the possibility that environmental toxic metal contaminants in recent years are associated with the increased risk of stroke.

Association Between Serum Copper and Stroke Risk Factors in Adults: Evidence from the National Health and Nutrition Examination Survey, 2011-2016

Copper as an essential trace element is hypothesized to be involved in stroke risk. However, the evidence for associations between copper and stroke risk factors such as lipid levels has been mixed. This study aimed to examine the relationships between serum copper and lipid levels among 3425 participants aged 20 years and older from the 2011-2016 National Health and Nutrition Examination Survey (NHANES). Data on administered questionnaires, serum copper concentrations, and lipid levels (total cholesterol, HDL cholesterol, triglycerides, and LDL cholesterol) were used. Associations between serum copper and lipid levels were evaluated using both multivariable linear regression and logistic regression models. In the linear regression models, total cholesterol and LDL cholesterol levels increased with increasing copper concentrations among women. Each 1 unit (μg/dL) increase in serum copper concentrations was associated with roughly 0.11 mg/dL higher total cholesterol (95%CI: 0.04-0.18; P < 0.05) and roughly 0.09 mg/dL higher LDL cholesterol (95%CI: 0.01-0.17; P < 0.05) among women, respectively. Serum copper was positively associated with high LDL cholesterol among women, and the multivariate-adjusted OR (95% CI) for the third quartile of serum copper concentrations was 4.25 (1.15-15.77) compared with the lowest quartile. Moreover, compared with the lowest quartile, the multivariate-adjusted OR (95% CI) for the third quartile of serum copper concentrations was 1.82 (1.16-2.85) for risk of having high total cholesterol among men. No significant association between serum copper and triglycerides levels was observed. These findings suggest that copper may impact stroke health via effects on lipid levels but need to be confirmed with prospective data.

Serum/Plasma Zinc Is Apparently Increased in Ischemic Stroke: a Meta-analysis

Zinc (Zn) is found in many neuronal pathways in the brain and has implications for neuromodulation and cerebrovascular disease. However, the association between Zn levels and stroke risk remains controversial. Therefore, we conducted a meta-analysis to explore these relationships. A systematic literature search using PubMed, EMBASE database, and Google Scholar was performed for relevant articles from inception to August 2020. Standardized mean differences (SMDs) and 95% confidence intervals (CIs) were considered the effect sizes and statistical analyses were performed using Stata 12.0. A total of 12 studies involving 1878 cases of stroke and 1754 controls were enrolled. Overall, the meta-analysis demonstrated no significant difference in Zn levels between the stroke group and control group (SMD =-0.18, 95% CI =-0.69 to 0.32, P = 0.480). Subgroup analysis showed that type of stroke had an influence on the Zn levels. A meta-analysis of nine ischemic stroke (IS) studies, which included 1645 cases and 1585 controls, revealed that the Zn levels were significantly higher in IS patients than in controls (SMD (95% CI): 0.61(0.04, 1.19), P = 0.036), but no significant association was found between Zn levels and risk of hemorrhagic stroke (P = 0.113). Egger's test indicated no significant publication bias. This meta-analysis indicates that higher Zn levels may be associated with increased risk of IS; however, these findings should be further confirmed.

Diet-Derived Circulating Antioxidants and Risk of Stroke: A Mendelian Randomization Study

Background

Oxidative stress is crucial in stroke pathogenesis. Many cohort-based studies suggested that the intake of exogenous antioxidants originated from food may prevent stroke. However, the corresponding randomized controlled trials did not show diet-derived antioxidants have a protective effect on stroke.

Objectives

To examine the association of genetically proxied diet-derived antioxidants with stroke risk using Mendelian randomization.

Methods

We performed a two-sample Mendelian randomization (MR) analysis to evaluate the causal effect of diet-derived antioxidants on stroke risk. For exposure data, we extracted genetic variants as instrumental variables (IVs) that are strongly associated with frequently used diet-derived antioxidants, including vitamin C, vitamin E (α-tocopherol, γ-tocopherol), carotene, retinol, zinc, and selenium, from a large-scale genome-wide association study (GWAS). We obtained IVs' corresponding effect estimates on the risk of total stroke and ischemic stroke from a GWAS meta-analysis with 40,585 cases and 406,111 controls. Finally, we applied five types of Mendelian randomization analysis to obtain preliminary MR results and performed four three kinds of sensitivity analysis to verify them.

Results

According to the primary MR estimations and further sensitivity analyses, we established two robust associations after Bonferroni correction: genetically proxied circulating γ-tocopherol was causally associated with total stroke [odds ratio (OR) = 0.68, 95% confidence interval (CI) (0.52-0.88), p = 3.78E − 03] and ischemic stroke [OR = 0.66, 95% CI (0.51-0.86), p = 2.34E − 03]. There was no evidence to support the causal effect of other diet-derived antioxidants on the risk of total stroke and ischemic stroke.

Conclusion

Our study revealed a protective impact of genetic susceptibility to high circulating γ-tocopherol levels on stroke risk, providing new information on the potential therapeutic targets for primary stroke prevention.

Plasma selenium and the risk of first stroke in adults with hypertension: a secondary analysis of the China Stroke Primary Prevention Trial

BACKGROUND

Previous studies have indicated that selenium (Se) may play an important role in cardio-cerebrovascular disease. However, the relation between circulating selenium and risk of first stroke remains inconclusive.

OBJECTIVES

We conducted a secondary analysis of the China Stroke Primary Prevention Trial (CSPPT), using a nested case-control design, and aimed to investigate the correlation between Se concentration and first stroke risk in adults with hypertension and examine the potential effect modifiers.

METHODS

In the CSPPT, a total of 20,702 adults with hypertension were randomly assigned to a double-blind daily treatment with either 10 mg enalapril and 0.8 mg folic acid or 10 mg enalapril alone. A total of 618 first stroke cases and 618 controls matched for age, sex, treatment group, and study site were included in this study.

RESULTS

During a median follow-up duration of 4.5 y (IQR: 4.2-4.6 y), there was a significant inverse association between plasma Se and the risk of first stroke (per SD increment; adjusted OR: 0.81; 95% CI: 0.68, 0.96) and ischemic stroke (per SD increment; adjusted OR: 0.76; 95% CI: 0.62, 0.93). Furthermore, a stronger inverse association between plasma Se and first stroke was observed in participants with higher folate concentrations at baseline [≥7.7 ng/mL (median), adjusted OR: 0.67; 95% CI: 0.54, 0.85, compared with <7.7 ng/mL, adjusted OR: 0.98; 95% CI: 0.80, 1.21; P-interaction = 0.008] and those with higher time-averaged systolic blood pressure (SBP) over the treatment period (≥140 mm Hg, adjusted OR: 0.71; 95% CI: 0.58, 0.86, compared with <140 mm Hg, adjusted OR: 0.96; 95% CI: 0.77, 1.20; P-interaction = 0.023).

CONCLUSIONS

There was a significant inverse association between plasma Se and risk of first stroke in Chinese adults with hypertension, especially among those with higher baseline folate concentrations and those with higher time-averaged SBP over the treatment period. This trial was registered at clinicaltrials.gov as NCT00794885.

Sex difference in the association between plasma selenium and first stroke: a community-based nested case-control study

BACKGROUND

To date, there is no clearly defined association between plasma selenium levels and first stroke. We aimed to investigate the association between baseline plasma selenium and first stroke risk in a community-based Chinese population.

METHODS

Using a nested case-control study design, a total of 1255 first stroke cases and 1255 matched controls were analyzed. Participant plasma selenium concentrations were measured by inductively coupled plasma mass spectrometry (ICP-MS), and the association of plasma selenium with first stroke risk was estimated by conditional logistic regression models.

RESULTS

Overall, a non-linear negative association between plasma selenium and first total stroke and first ischemic stroke risks was found in males but not in females. Compared with participants with lower selenium levels (tertile 1-2, < 94.1 ng/mL), participants with higher selenium levels (tertile 3, ≥ 94.1 ng/mL) had significantly lower risks of first total stroke (OR 0.63; 95% CI 0.48, 0.83) and first ischemic stroke (OR 0.61; 95% CI 0.45, 0.83) in males but not in females with first total stroke (OR 0.92; 95% CI 0.69, 1.22) and first ischemic stroke (OR 0.89; 95% CI 0.65, 1.22). Furthermore, a stronger association between plasma selenium and first total stroke was found in males with higher vitamin E levels (≥ 13.5 μg/mL vs. < 13.5 μg/mL P-interaction = 0.007). No significant association was observed between plasma selenium and first hemorrhagic stroke risk in either males or females.

CONCLUSION

Our study indicated a significant, non-linear, negative association between plasma selenium and first stroke in males but not in females.

TRIAL REGISTRATION

ChiCTR1800017274 .

Association between plasma copper levels and first stroke: a community-based nested case-control study

BACKGROUND AND AIMS

Uncertainty remains regarding the association between the risk of stroke and plasma copper levels in population with copper mostly in normal range due to limited data. We examined the association between baseline plasma copper and risk of first stroke in Chinese community-dwelling population.

METHODS

We conducted a nested case control study from 'H-type Hypertension and Stroke Prevention and Control Project'. A total of 1255 first stroke cases and 1255 controls matched for age, sex and study site were included in the analysis. Conditional logistic regression analyses were performed to evaluate the association between plasma copper and first stroke.

RESULTS

The overall mean of copper was 15.90 (2.66) μmol/L. In total, 94.26% participants' copper concentration was in the normal range by Mayo Clinic laboratory reference values. Smoothing curve showed that the associations of plasma copper with first stroke and its subtypes were linear. Each standard deviation (SD) increment of plasma copper was independently and positively associated with risk of first stroke [odds ratio (OR): 1.17, 95% confidence interval (CI): 1.07-1.28]. The multivariable ORs with 95% CIs for total stroke, ischemic stroke and hemorrhagic stroke in the highest versus the lowest quartile of plasma copper were 1.49 (1.16-1.90; P-trend = 0.001), 1.46 (1.12-1.92; P-trend = 0.004) and 2.05 (0.95-4.38; P-trend = 0.050), respectively.

CONCLUSIONS

Baseline plasma copper was positively associated with risk of first ischemic stroke in an approximately linear fashion among Chinese community population (80.32% hypertensives), although their copper levels were mostly within the normal range according to current reference values. Our findings warrant additional investigation.

Zinc Deficiency-An Independent Risk Factor in the Pathogenesis of Haemorrhagic Stroke?

Zinc is an essential trace element for human health and plays a fundamental role in metabolic, immunological and many other biological processes. The effects of zinc are based on the intra- and extracellular regulatory function of the zinc ion (Zn2+) and its interactions with proteins. The regulation of cellular zinc homeostasis takes place via a complex network of metal transporters and buffering systems that react to changes in the availability of zinc in nutrition, chronic diseases, infections and many other processes. Zinc deficiency is associated with impairment of numerous metabolic processes, reduced resistance to infections due to impaired immune functions, changes in skin and its appendages and disorders of wound healing and haemostasis. While ischemic heart attacks (myocardial infarction) occur more frequently with meat-based normal diets, haemorrhagic strokes are more frequently observed with vegetarian/vegan diets. The causes are discussed as deficiencies of various micronutrients, such as vitamin B12, vitamin D, various amino acids and also zinc. In the present review, after a description of the functions of zinc and its resorption, a discussion of daily food intake will follow, with a special focus on the importance of food composition and preparation for the zinc balance. The close interrelationships between proteins, especially albumin and zinc will be discussed. Finally, the possible causes and consequences of a zinc deficiency on the blood vessels and blood coagulation are considered.