Association between dietary zinc intake and mortality among Chinese adults: findings from 10-year follow-up in the Jiangsu Nutrition Study

Associations of multiple metal intake with all-cause and cardiovascular mortality in US adults stratified by age and sex: A prospective cohort from the NHANES database study

AIM AND OBJECTIVES

The relationship between dietary metal intake and mortality risk is controversial, and we investigated the relationship between intake of five metals (iron, copper, selenium, zinc, and magnesium) and all-cause, cardiovascular mortality in the total population, gender subgroups, and age subgroups.

MATERIALS AND METHODS

17,207 participants from the National Health and Nutrition Examination Survey (NHANES) database from 2009 to 2016 were included in this study. Kaplan-Meier survival curves, multivariate Cox proportional hazards models, and restrictive cubic spline (RCS) curves were used to explore the association between metal intake and all-cause, cardiovascular mortality.

RESULTS

In this study, the average dietary metal intake of men and older people was lower than that of women and younger people. The RCS curves found in the whole population that all-cause mortality was negative linearly associated with copper intakes, L-shaped with zinc and magnesium intakes. Further subgroup analyses of copper, zinc, and magnesium by age and gender revealed that only magnesium showed statistically significant differences in the age subgroups. In the 20-40 population, there was a non-linear increasing trend in magnesium intake and all-cause mortality, whereas there was a non-linear decreasing trend in the > 60 population.

CONCLUSION

The relationship between metal intake and mortality is more than a simple linear correlation, and differences in age can affect this correlation. In metal exposure studies, different populations can be studied to better determine the effect of metal exposure on mortality.

DATA AVAILABILITY

The dataset used for statistical analysis in this study is available on the NHANES website: https://www.cdc.gov/nchs/nhanes/index.htm.

Association of composite dietary antioxidant index with depression and all-cause mortality in middle-aged and elderly population

Current research has shown an increasing acceptance of interventions for depression through dietary modifications. However, whether composite dietary antioxidant index (CDAI) is associated with depression and all-cause mortality in middle-aged and elderly population remains unknown. This study aimed to explore those associations in American middle-aged and elderly population. Weighted logistic regression models and weighted Cox proportional hazard regression models were used to assess the association of CDAI, covariates, depression, and all-cause mortality, respectively. The stability of the results was also determined by a linear trend test based on CDAI quintiles. Restricted cubic spline curves were employed to test for non-linear relationships. In the model adjusted for all covariates, significant associations were found with the ORs (95% CI) for CDAI and depression [0.77 (0.67, 0.89)] and the HRs (95% CI) for CDAI with all-cause mortality[0.91 (0.83, 1.00)]. Upon conducting restricted cubic spline curves, we found that the association between CDAI and depression was linear, whereas the association between CDAI and all-cause mortality was non-linear with an inflection point of -0.19. Statistical significance was only found before the inflection point. In this study of middle-aged and elderly Americans, CDAI was linearly negatively associated with depression and non-linearly negatively associated with all-cause mortality.

The adverse association of animal zinc intake with cardio-cerebrovascular and metabolic risk factors

Background

The effect of zinc intake on cardio-cerebrovascular and metabolic diseases has always been controversial.

Aims

We hoped to evaluate the associations of the daily dietary estimate (DDE) of zinc intake with cardio-cerebrovascular and metabolic risk factors.

Methods

Baseline data from the Study of Women's Health Across the Nation (SWAN) were obtained. Multivariable linear regression analysis was used to examine associations of the DDE of zinc intake with cardio-cerebrovascular and metabolic risk factors.

Results

The smooth curve demonstrated positive associations of the DDE of animal zinc intake with low-density lipoprotein-cholesterol (LDL-C), triglycerides, total cholesterol, fasting blood glucose, insulin, systolic blood pressure (BP) and diastolic BP and an inverse association of the DDE of animal zinc intake with high-density lipoprotein-cholesterol (HDL-C). Consistently, multivariable linear regression models also showed that an increased DDE of animal zinc intake was closely related to a higher risk of cardio-cerebrovascular and metabolic risk factors [systolic BP: 0.37 (0.13, 0.61); diastolic BP: 0.17 (0.02, 0.33); fasting blood glucose: 1.13 (0.67, 1.59); insulin: 0.26 (0.05, 0.47); LDL-C: 0.82 (0.34, 1.29), triglycerides: 1.65 (0.75, 2.55), total cholesterol: 0.91 (0.38, 1.43) and HDL-C: -0.24 (-0.45, -0.03)] when age, race/ethnicity, total family income, smoking status, alcohol consumption and menopausal status were controlled for. Importantly, stratified analysis supported that the independent associations between the DDE of animal zinc intake and risk factors for cardio-cerebrovascular and metabolic diseases were hardly affected by age and body mass index (BMI).

Conclusion

We found that an increased DDE of animal zinc intake was associated with higher cardiovascular and metabolic risks among middle-aged women, which did not support the benefit of zinc intake in reducing cardiovascular and metabolic risks. The association seems to be incongruous with the anti-inflammation and antioxidation physiological functions of zinc. Thus, additional well-designed and prospective studies are needed to confirm this association.

Selenium in Cancer Rehabilitation-A Retrospective Study from a Specialized Clinic

BACKGROUND

Micronutrient deficiencies are common at the time of cancer diagnosis and are associated with worse prognosis. Little is known about them in cancer rehabilitation.

METHODS

Data from routine health-related quality of life (HRQOL) were analyzed at an inpatient cancer rehabilitation center. Rehabilitation patients completed the EORTC QLQ-C30 questionnaire before and after multidisciplinary rehabilitation treatment and three months after discharge. Selenium and zinc status were measured in whole blood at these three time points. In case of selenium deficiency, up to 600 µg selenium per day as sodium selenite was supplemented for three weeks during and for three months after rehabilitation.

RESULTS

A total of 271 patients (breast, colon, and pancreatic cancer) were included in the analysis. There was clinically meaningful improvement in many domains of the EORTC QLQ-C30 during rehabilitation. However, the effect often waned in the three months after. Prevalence for selenium deficiency varied between 34 to 90% depending on cancer type (breast < colon < pancreas). In contrast, zinc deficiency was rare. Daily selenium supplementation of 600 µg was more efficient to correct selenium deficiency compared to 300 µg selenium per day. Rehabilitation and increasing selenium status after rehabilitation were associated with improved global quality of life, physical and emotional functioning, and fatigue. In cancer patients with decreasing selenium status, values of global quality of life, physical and emotional functioning, and fatigue were back to the values at the beginning of rehabilitation.

CONCLUSIONS

Selenium deficiency is common in cancer patients admitted to a cancer rehabilitation clinic. Selenium supplementation during rehabilitation effectively corrected selenium deficiency in most cases. The positive effects of rehabilitation persisted longer when selenium status did not decrease after rehabilitation.

A Systematic Study on Zinc-Related Metabolism in Breast Cancer

Breast cancer has become the most common cancer worldwide. Despite the major advances made in the past few decades in the treatment of breast cancer using a combination of chemotherapy, endocrine therapy, and immunotherapy, the genesis, treatment, recurrence, and metastasis of this disease continue to pose significant difficulties. New treatment approaches are therefore urgently required. Zinc is an important trace element that is involved in regulating various enzymatic, metabolic, and cellular processes in the human body. Several studies have shown that abnormal zinc homeostasis can lead to the onset and progression of various diseases, including breast cancer. This review highlights the role played by zinc transporters in pathogenesis, apoptosis, signal transduction, and potential clinical applications in breast cancer. Additionally, the translation of the clinical applications of zinc and associated molecules in breast cancer, as well as the recent developments in the zinc-related drug targets for breast cancer treatment, is discussed. These developments offer novel insights into understanding the concepts and approaches that could be used for the diagnosis and management of breast cancer.

L-shaped association between dietary zinc intake and the risk of developing cardiovascular disease in Chinese adults: A cohort study

Background

Although the association of zinc (Zn) with cardiovascular disease (CVD) has been studied, no consensus has been reached on this relationship, particularly dietary Zn intake. The purpose of this study was to assess the effect of dietary Zn intake on the risk of CVD and to analyze whether this effect varied according to zinc consumption using representative data from China.

Methods

11,470 adults from the China Health and Nutrition Survey (CHNS) were eventually enrolled. The dietary information was collected by the 3 day 24-h dietary recalls combined with dietary weighting method. CVD was defined as participants with self-reported physician-diagnosed apoplexy and/or myocardial infarction during the follow-up. Cox regression was used to calculate the hazard ratios (HRs) of CVD with 95% confidence intervals. Restricted cubic spline function plus Cox regression was used to visualize the influence trend of dietary Zn intake on new-onset CVD and to test whether this trend is linear. 2-segment Cox regression was established to address the nonlinear trend.

Results

431 participants developed CVD, including 262 strokes and 197 myocardial infarctions. Compared with the lowest quintile (Q1), the adjusted hazard ratios and 95% confidence interval (CI) of CVD in Q2 to Q5 of dietary Zn intake were 0.72 (0.54, 0.97), 0.59 (0.42, 0.81), 0.50 (0.34, 0.72) and 0.44 (0.27, 0.71), respectively. The influence trend of dietary Zn intake on new-onset CVD was nonlinear and L-shaped. When dietary Zn intake &lt;13.66 mg/day, increased dietary Zn intake was significantly associated with decreased risk of developing CVD (HR = 0.87, 95% CI: 0.82–0.92, p-value &lt;0.0001).

Conclusion

An L-shaped trend was observed between dietary Zn intake and the risk of developing CVD, indicating that dietary Zn intake should be improved moderately, but not excessively, for the benefit of cardiovascular disease.

Composite Dietary Antioxidant Index and Plasma Levels of Soluble Klotho: Insights from NHANES

Objectives

The association between dietary antioxidants and soluble Klotho (S-Klotho) levels remains unknown. We investigated to explore whether the composite dietary antioxidant index (CDAI) was associated with serum levels of S-Klotho in the middle-aged population.

Methods

Eligible participants were identified from the National Health and Nutrition Examination Surveys (NHANES) from 2007 until 2016. The CDAI was calculated from the intake of six dietary antioxidants. The serum levels of S-Klotho were measured via enzyme-linked immunosorbent assay (ELISA). Generalized linear and nonlinear models were established to analyze the relationship between CDAI and S-Klotho levels.

Results

Based on the S-Klotho quartiles, S-Klotho levels were higher in young women, Blacks, higher education, never smokers, lower waistlines, no medication use, and those with higher CDAI. Univariate analysis revealed that age, gender, race, smoking status, body mass index, waistline, and medication use were associated with serum levels of S-Klotho. When potential confounders were controlled, CDAI was significantly associated with S-Klotho levels. Subgroup analysis also revealed that this association remained significant in individuals who had the highest quartiles of CDAI, aged population (>60 years), male, and never smoker. A nonlinear relationship was observed between the CDAI and S-Klotho plasma concentrations.

Conclusion

CDAI was positively correlated with plasma levels of S-Klotho after controlling for covariates. Further studies are needed to validate the current findings and explore the fundamental mechanisms.

Associations of Dietary Zinc-Vitamin B6 Ratio with All-Cause Mortality and Cardiovascular Disease Mortality Based on National Health and Nutrition Examination Survey 1999-2016

Previous studies have suggested a possible association among dietary zinc and vitamin B6 intake and CVD mortality and all-cause mortality. However, evidence on the association of dietary zinc and vitamin B6 intake and their interactions with CVD mortality and all-cause mortality remains unclear. This prospective study utilized data from the US National Health and Nutrition Examination Survey (NHANES) from 1999 to 2016. After a median follow-up of 10.4 years, 4757 deaths were recorded among 36,081 participants. Higher dietary zinc intake levels (≥9.87 mg/day) were associated with lower CVD mortality (hazard ratio (HR) = 0.85, 95% confidence interval (CI): 0.83−0.87). Vitamin B6 intake levels (≥1.73 mg/day) were associated with lower CVD mortality (HR = 0.91, 95% CI: 0.86−0.96) and all-cause mortality (HR = 0.91, 95% CI: 0.90−0.93). Higher dietary zinc intake and higher vitamin B6 intake were associated with a lower risk of CVD mortality, with an interaction between dietary zinc intake levels and vitamin B intake levels (LZLV group (HR, CI): 1.21,1.12−1.29; LZHV group (HR, CI): 1.42, 1.34−1.50; LZHV group (HR, CI): 1.28, 1.14−1.45; HZHV group (HR, CI): ref). There was also a J-type association (p for nonlinear < 0.001) between the dietary zinc−vitamin B6 ratio and CVD mortality, with a high dietary zinc−vitamin B6 ratio increasing the risk of CVD mortality (HR = 1.27, 95% CI: 1.19−1.35), whereas a moderate dietary zinc−vitamin B6 ratio appeared to be beneficial for CVD mortality. These results suggest that increasing the appropriate proportion of dietary zinc and vitamin B6 intake is associated with a lower risk of CVD mortality. Furthermore, precise and representative studies are needed to verify our findings.

Dietary Zinc Intake and All-Cause and Cardiovascular Mortality in Korean Middle-Aged and Older Adults

We aimed to investigate the association between dietary zinc intake and total deaths, cancer, and cardiovascular disease death. In this prospective, 10-year, community-based cohort analysis, data from 143,050 adult participants (aged 40 years and older) were analyzed. Dietary zinc intake at baseline was assessed using a food frequency questionnaire. Harrell’s C-index was used to determine the optimal cut-off of dietary zinc intake with the log-rank test. Using the Cox proportional hazards regression models, the association between dietary zinc intake and all-cause, cancer, and cardiovascular disease mortality was estimated using hazard ratios and 95% confidence intervals. During the mean 10.1 years of follow-up, 5436 participants expired, of whom 2355 died due to cancer and 985 died due to cardiovascular causes. After adjustment for confounders, dietary zinc intake was inversely associated with all-cause mortality (≤5.60 mg/day vs. >7.98 mg/day; hazard ratio, 1.13; 95% confidence interval, 1.01−1.25) and cardiovascular disease mortality (≤5.12 mg/day vs. >7.28 mg/day; hazard ratio, 1.42; 95% confidence interval, 1.11−1.81) but not with cancer mortality (≤5.60 mg/day vs. >10.08 mg/day; hazard ratio, 1.09; 95% confidence interval, 0.90−1.33). Dietary zinc intake was associated with a lower risk of all-cause mortality and cardiovascular disease mortality but not with cancer mortality. Our findings could suggest that recommending optimal dietary zinc intake is helpful for human health.

High Dietary Zinc Intake Is Associated with Shorter Leukocyte Telomere Length, Mediated by Tumor Necrosis Factor-α: A Study of China Adults

OBJECTIVES

Diet can influence peripheral leukocyte telomere length (LTL), and various micronutrients have been reported to correlate with it. Zinc is known for its antioxidant properties and immunomodulatory effects. However, there are few epidemiological investigations on the relationship between dietary zinc intake and LTL. This study analyzed the association between dietary zinc and LTL and the potential role of inflammation and oxidative stress among them.

DESIGN

Cross-sectional and community-based study.

SETTING AND PARTICIPANTS

599 participants from rural communities in the Changping suburb of Beijing, China, were recruited.

MEASUREMENTS

Serum lipid profile, glycosylated hemoglobin (HbA1c), oxidative stress marker, and inflammatory cytokines levels were measured. Detailed dietary data were obtained using a 24 h food recall. LTL was assessed using a real-time PCR assay. Spearman analysis, restricted cubic splines (RCS), and general linear regression models were used to determine the association between dietary zinc intake and LTL. Simple regulatory models were also applied to analyze the role of inflammation and oxidative stress among them.

RESULTS

A total of 482 subjects were ultimately included in this analysis. Spearman analysis showed that dietary zinc intake and zinc intake under energy density were negatively correlated with LTL (r=-0.142 and -0.126, all P <0.05) and positively correlated with tumor necrosis factor-α (TNF-α) (r=0.138 and 0.202, all P <0.05) while only dietary zinc without energy adjustment had a positive correlation with superoxide dismutase (SOD). RCS (P for non-linearity=0.933) and multiple linear regression (B=-0.084, P=0.009) indicated a negative linear association between dietary zinc and LTL. The adjustment of TNF-α rather than SOD could abolish the relationship. The mediation model suggested that the unfavorable effect of dietary zinc on LTL was mediated by TNF-α.

CONCLUSIONS

High dietary zinc may correlate with telomere attrition, and TNF-α can act as a mediator in this relationship. In the future, more extensive cohort studies are needed to further explore the relationship between dietary zinc and cellular aging and the specific mechanisms.

Dietary zinc intake and mortality in patients with intestinal-type gastric cancer: A prospective cohort study in Korea

Purpose

Current evidence regarding the association between zinc intake and gastric cancer (GC)-specific survival in patients with intestinal-type GC is lacking. Therefore, this cohort study investigated the association between zinc intake and GC mortality through follow-up on GC death among patients with intestinal-type GC and whether these effects differ according to the source of zinc intake.

Methods

A total of 185 patients with intestinal-type GC were enrolled from two hospitals between 2002 and 2006. Their survival or death was prospectively followed up until December 31, 2016, through a review of medical records and telephone surveys.

Results

A total of 178 patients were included and analyzed. The median follow-up period was 7.3 years. In the fully adjusted models, the highest tertile of total zinc intake showed a significantly lower GC mortality than the lowest tertile (hazard ratio, 0.22; 95% confidence interval: 0.08–0.64). In addition, the tertile of total zinc intake showed a dose-response association with GC mortality (p=0.015). Analysis of the source of zinc intake revealed that when zinc intake from staples (rice and noodles), animal, and plant food sources were combined, the results were similar to those of total zinc intake and GC mortality.

Conclusion

Zinc intake through various foods may be effective in reducing GC mortality by achieving balance with other nutrients. Our results suggest that zinc improves the survival of patients with intestinal-type GC in Korea.

Zinc and Breast Cancer Survival: A Prospective Cohort Study of Dietary Intake and Serum Levels

Zinc has been suggested to play a role in breast cancer progression; however, no previous study on zinc levels and the potential effect on breast cancer survival has been conducted. This study investigates recurrence-free survival (RFS), breast cancer-specific survival (BCSS) and overall survival (OS) in relation to zinc levels, in serum and diet, overall and stratified for phosphorus and selenium levels. The Malmö Diet and Cancer Study, a prospective population-based cohort in Sweden including 17,035 women, was used to identify breast cancer patients diagnosed in the period 1991–2013. Diet was assessed by a validated modified diet history method. A Cox regression analysis yielded hazard ratios (HRs) with 95% confidence intervals adjusted for potential confounders. Out of 1062 patients with invasive breast cancer, 268 recurrences, 205 breast cancer deaths and 228 deaths from other causes were recorded. No overall associations were seen between zinc and RFS, BCSS or OS. However, in women with a high phosphorus intake, a higher BCSS and OS were seen in zinc intake Q2 to Q4 versus Q1; the adjusted HR was 0.41 (0.23–0.73) and 0.64 (0.41–1.00), respectively. The results indicate that the combination of intermediate/high zinc intake and high phosphorus intake may lead to a better breast cancer survival.

Dietary Antioxidant Indices in Relation to All-Cause and Cause-Specific Mortality Among Adults With Diabetes: A Prospective Cohort Study

Background

The potential beneficial effect of individual antioxidants on mortality has been reported. However, the association of overall intakes of dietary antioxidants with all-cause and cause-specific mortality among adults with diabetes remained unclear.

Methods

A total of 4,699 US adults with diabetes were enrolled in 2003–2014 in the National Health and Nutrition Examination Survey (NHANES) and followed for mortality until 31 December 2015. The Dietary Antioxidant Quality Score (DAQS) and the Dietary Antioxidant Index (DAI), which indicate the total antioxidant properties, were calculated based on the intakes of vitamins A, C, E, zinc, selenium, and magnesium. The Cox proportional hazards regression models were used to investigate the associations of the DAQS or the DAI with all-cause and cause-specific mortality.

Results

A total of 913 deaths occurred during 27,735 person-years of follow-up, including 215 deaths due to cardiovascular disease (CVD) and 173 deaths due to cancer. The higher intakes of antioxidant vitamins A, E, magnesium, and selenium were associated with lower all-cause mortality. The adjusted hazard ratios (HRs) (95% CIs) comparing the highest DAQS (5–6) to the lowest DAQS (0–2) were 0.70 (0.53–0.92) for all-cause mortality, 0.56 (0.35–0.90) for CVD mortality, and 0.59 (0.33–1.04) for cancer mortality. Consistent inverse associations were found between the DAI and mortality.

Conclusion

Higher intake of overall dietary antioxidants was associated with lower risk of death from all-cause and CVD in adults with diabetes. Future dietary intervention studies are needed to determine whether increasing overall antioxidant micronutrients intake could prevent premature death among adults with diabetes.

The Impact of Micronutrients-Calcium, Vitamin D, Selenium, Zinc in Cardiovascular Health: A Mini Review

The role of micronutrients in health and disease has increased the curiosity and interest among researchers. The prime focus of this review is the significance of trace elements- calcium, vitamin D, selenium and zinc with cardiovascular health. WHO identified cardiovascular diseases (CVD) as the leading cause of deaths globally. Identifying the risk factors that could be modified and creating new treatment strategies remains to be the main concern for CVD prevention. The data that showed the relationship between trace elements and various ways in which they may contribute to cardiovascular health and disease from clinical trials and observational studies were collected from databases such as PubMed and Embase. Based on these collected data, it shows that either high or low circulating serum levels can be associated with the development of cardiovascular diseases. Micronutrients through diet contribute to improved cardiac health. However, due to our current lifestyle, there is a huge dependency on dietary supplements. Based on the observational studies, it is evident that supplements cause sudden increase in the circulating levels of the nutrients and result in cardiovascular damage. Thus, it is advisable to restrict the use of supplements, owing to the potent risks it may cause. In order to understand the exact mechanism between micronutrients and cardiac health, more clinical studies are required.

Association of Zinc Deficiency with Development of CVD Events in Patients with CKD

Deficiency of the micronutrient zinc is common in patients with chronic kidney disease (CKD). The aim of this review is to summarize evidence presented in literature for consolidation of current knowledge regarding zinc status in CKD patients, including those undergoing hemodialysis. Zinc deficiency is known to be associated with various risk factors for cardiovascular disease (CVD), such as increased blood pressure, dyslipidemia, type 2 diabetes mellitus, inflammation, and oxidative stress. Zinc may protect against phosphate-induced arterial calcification by suppressing activation of nuclear factor kappa light chain enhancer of activated B. Serum zinc levels have been shown to be positively correlated with T₅₀ (shorter T₅₀ indicates higher calcification propensity) in patients with type 2 diabetes mellitus as well as those with CKD. Additionally, higher intake of dietary zinc was associated with a lower risk of severe abdominal aortic calcification. In hemodialysis patients, the beneficial effects of zinc supplementation in relation to serum zinc and oxidative stress levels was demonstrated in a meta-analysis of 15 randomized controlled trials. Thus, evidence presented supports important roles of zinc regarding antioxidative stress and suppression of calcification and indicates that zinc intake/supplementation may help to ameliorate CVD risk factors in CKD patients.

The importance of selenium and zinc deficiency in cardiovascular disorders

Cardiovascular diseases often linked with lifestyle are among the main causes of death, especially in the elderly population. The role of trace elements in health and disease has been emphasized in multiple scientific research. Moreover, supplementation of trace elements to improve health is becoming increasingly popular. The following paper presents current views on the relationship between the concentration of trace elements such as selenium and zinc in the body, as well as morphology and function of the cardiovascular system. Research discussing the effect of selenium and zinc supplementation on the function of the heart and blood vessels was also reviewed. The relationship between selenium and zinc concentration and morphology and function of the cardiovascular system is equally unclear, and therefore there is currently no scientific evidence for its supplementation for preventing cardiovascular diseases. It seems justified to continue scientific research on this subject due to the small number of experimental studies available on the topic of selenium and zinc deficiency and their impact on the cardiovascular system.

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.

Association of dietary zinc intake with coronary artery calcium progression: the Multi-Ethnic Study of Atherosclerosis (MESA)

PURPOSE

Zinc is considered protective against atherosclerosis; however, the association between dietary zinc intake and cardiovascular disease remains debated. We investigated whether dietary zinc intake was associated with coronary artery calcium (CAC) progression in the Multi-Ethnic Study of Atherosclerosis (MESA).

METHODS

This analysis included 5186 participants aged 61.9 ± 10.2 years (48.8% men; 41.3% white, 25.0% black, 21.6% Hispanic, and 12.1% Chinese American) from the MESA. Dietary zinc intake was assessed by a self-administered, 120-item food frequency questionnaire at baseline (2000-2002). Baseline and follow-up CAC were measured by computed tomography. CAC progression was defined as CAC > 0 at follow-up for participants with CAC = 0 at baseline; and an annualized change of 10 or percent change of ≥ 10% for those with 0 < CAC < 100 or CAC ≥ 100 at baseline, respectively.

RESULTS

Dietary zinc intake was 8.4 ± 4.5 mg/day and 2537 (48.9%) of the included participants had CAC at baseline. Over a median follow-up of 3.4 years (25th-75th percentiles = 2.0-9.1 years), 2704 (52.1%) participants had CAC progression. In the fully adjusted model, higher dietary zinc was associated with a lower risk of CAC progression in both men (hazard ratio [HR] 0.697, 95% confidence interval [CI] 0.553-0.878; p = 0.002) and women (HR 0.675; 95% CI 0.496-0.919; p = 0.012, both comparing extreme groups). Furthermore, such an inverse association was attributable to dietary zinc intake from non-red meat (p < 0.05), rather than red meat sources (p > 0.05).

CONCLUSIONS

In this multiethnic population free of clinically apparent cardiovascular disease, higher dietary zinc intake from non-red meat sources was independently associated with a lower risk of CAC progression.

CLINICAL TRIAL REGISTRATION NUMBER

The MESA trial was registered at clinicaltrials.gov as NCT00005487.

Dietary zinc intake and incident chronic kidney disease

BACKGROUND & AIMS

Previous studies have shown that dietary zinc intake is closely related to cardiovascular complications and metabolic derangements. However, the effect of dietary zinc intake on renal function is not fully elucidated.

METHODS

Data from the Korean Genome and Epidemiology Study were used. Dietary zinc intake was assessed by a Food Frequency Questionnaire and dietary zinc density was calculated as absolute zinc intake amount per daily energy intake (mg/1000 kcal day). The participants were categorized into quartiles according to dietary zinc density. The primary end point was incident chronic kidney disease (CKD), defined as estimated glomerular filtration rate (eGFR) < 60 ml/min/1.73 m².

RESULTS

A total of 7735 participants with normal renal function was included in the final analysis. The mean age was 52.0 ± 8.8 years, 47.5% were male, and mean eGFR was 92.1 ± 16.1 ml/min/1.73 m². The mean daily zinc intake and zinc intake density were 8.6 ± 3.4 mg and 4.4 ± 0.9 mg/1000 kcal, respectively. During a median follow up of 11.5 (1.7-12.5) years and 70,617 person-years of observation, CKD developed in 1409 (18.2%) participants. Multivariable cox hazard analysis revealed that risk for CKD development was significantly higher in the quartile with a mean zinc intake density of 3.6 ± 0.2 mg/1000 kcal compared with the quartile with a mean zinc intake density of 5.6 ± 1.0 mg/1000 kcal (Hazard ratio; 1.36; 95% Confidence Interval 1.18-1.58; P < 0.001). This relationship remained significant even after adjustments for confounding factors.

CONCLUSION

Low dietary zinc intake may increase the risk of CKD development in individuals with normal renal function.

Association between dietary zinc intake and abdominal aortic calcification in US adults

BACKGROUND

In animal studies, zinc supplementation inhibited phosphate-induced arterial calcification. We tested the hypothesis that higher intake of dietary zinc was associated with lower abdominal aortic calcification (AAC) among adults in the USA. We also explored the associations of AAC with supplemental zinc intake, total zinc intake and serum zinc level.

METHODS

We performed cross-sectional analyses of 2535 participants from the National Health and Nutrition Examination Survey 2013-14. Dietary and supplemental zinc intakes were obtained from two 24-h dietary recall interviews. Total zinc intake was the sum of dietary and supplemental zinc. AAC was measured using dual-energy X-ray absorptiometry in adults ≥40 years of age and quantified using the Kauppila score system. AAC scores were categorized into three groups: no AAC (AAC = 0, reference group), mild-moderate (AAC >0-≤6) and severe AAC (AAC >6).

RESULTS

Dietary zinc intake (mean ± SE) was 10.5 ± 0.1 mg/day; 28% had AAC (20% mild-moderate and 8% severe), 17% had diabetes mellitus and 51% had hypertension. Higher intake of dietary zinc was associated with lower odds of having severe AAC. Per 1 mg/day higher intake of dietary zinc, the odds of having severe AAC were 8% lower [adjusted odds ratio 0.92 (95% confidence interval 0.86-0.98), P = 0.01] compared with those without AAC, after adjusting for demographics, comorbidities and laboratory measurements. Supplemental zinc intake, total zinc intake and serum zinc level were not associated with AAC.

CONCLUSIONS

Higher intake of dietary zinc was independently associated with lower odds of having severe AAC among noninstitutionalized US adults.

Zinc Intake and Status and Risk of Type 2 Diabetes Mellitus: A Systematic Review and Meta-Analysis

Zinc could have a protective role against type 2 diabetes mellitus (T2DM). This systematic review and meta-analysis aimed to evaluate the association between dietary, supplementary, and total zinc intake, as well as serum/plasma and whole blood zinc concentration, and risk of T2DM. Observational studies, conducted on cases of incident diabetes or T2DM patients and healthy subjects that reported a measure of association between zinc exposure and T2DM, were selected. Random effects meta-analyses were applied to obtain combined results. Stratified meta-analyses and meta-regressions were executed to assess sources of heterogeneity, as well as the impact of covariates on the findings. From 12,136 publications, 16 studies were selected. The odds ratio (OR) for T2DM comparing the highest versus lowest zinc intake from diet was 0.87 (95% CI: 0.78–0.98). Nevertheless, no association between supplementary or total zinc intake from both diet and supplementation, and T2DM was observed. A direct relationship was found between serum/plasma zinc levels and T2DM (OR = 1.64, 95% CI: 1.25–2.14). A moderately high dietary zinc intake, in relation to the Dietary Reference Intake, could reduce by 13% the risk of T2DM, and up to 41% in rural areas. Conversely, elevated serum/plasma zinc concentration was associated with an increased risk of T2DM by 64%, suggesting disturbances in zinc homeostasis.

Dietary Antioxidants, Circulating Antioxidant Concentrations, Total Antioxidant Capacity, and Risk of All-Cause Mortality: A Systematic Review and Dose-Response Meta-Analysis of Prospective Observational Studies

The associations of various dietary or circulating antioxidants with the risk of all-cause mortality in the general population have not been established yet. A systematic search was performed in PubMed and Scopus, from their inception up to October 2017. Prospective observational studies reporting risk estimates of all-cause mortality in relation to dietary intake and/or circulating concentrations of antioxidants were included. Random-effects meta-analyses were conducted. Forty-one prospective observational studies (total n = 507,251) involving 73,965 cases of all-cause mortality were included. The RRs of all-cause mortality for the highest compared with the lowest category of circulating antioxidant concentrations were as follows: total carotenes, 0.60 (95% CI: 0.46, 0.74); vitamin C, 0.61 (95% CI: 0.53, 0.69); selenium, 0.62 (95% CI: 0.45, 0.79); β-carotene, 0.63 (95% CI: 0.57, 0.70); α-carotene, 0.68 (95% CI: 0.58, 0.78); total carotenoids, 0.68 (95% CI: 0.56, 0.80); lycopene, 0.75 (95% CI: 0.54, 0.97); and α-tocopherol, 0.84 (95% CI: 0.77, 0.91). The RRs for dietary intakes were: total carotenoids, 0.76 (95% CI: 0.66, 0.85); total antioxidant capacity, 0.77 (95% CI: 0.73, 0.81); selenium, 0.79 (95% CI: 0.73, 0.85); α-carotene, 0.79 (95% CI: 0.63, 0.94); β-carotene, 0.82 (95% CI: 0.77, 0.86); vitamin C, 0.88 (95% CI: 0.83, 0.94); and total carotenes, 0.89 (95% CI: 0.81, 0.97). A nonsignificant inverse association was found for dietary zinc, zeaxanthin, lutein, and vitamin E. The nonlinear dose-response meta-analyses demonstrated a linear inverse association in the analyses of dietary β-carotene and total antioxidant capacity, as well as in the analyses of circulating α-carotene, β-carotene, selenium, vitamin C, and total carotenoids. The association appeared to be U-shaped in the analyses of serum lycopene and dietary vitamin C. The present study indicates that adherence to a diet with high antioxidant properties may reduce the risk of all-cause mortality. Our results confirm current recommendations that promote higher intake of antioxidant-rich foods such as fruit and vegetables.