Serum zinc concentrations and characteristics of zinc deficiency/marginal deficiency among Japanese subjects

Zinc as a Possible Critical Element to Prevent Harmful Effects of COVID-19 on Testicular Function: a Narrative Review

Research into innovative non-pharmacological therapeutic routes via the utilization of natural elements like zinc (Zn) has been motivated by the discovery of new severe acute respiratory syndrome-related coronavirus 2 (SARS-COV2) variants and the ineffectiveness of certain vaccination treatments during COVID-19 pandemic. In addition, research on SARS-COV-2's viral cellular entry and infection mechanism has shown that it may seriously harm reproductive system cells and impair testicular function in young men and adolescents, which may lead to male infertility over time. In this context, we conducted a narrative review to give an overview of the data pertaining to Zn's critical role in testicular tissue, the therapeutic use of such micronutrients to enhance male fertility, as well as in the potential mitigation of COVID-19, with the ultimate goal of elucidating the hypothesis of the potential use of Zn supplements to prevent the possible harmful effects of SARS-COV2 infection on testis physiological function, and subsequently, on male fertility.

Association Between Serum Zinc Concentration Levels And Severity Of Coronavirus Disease 2019 (Covid-19) In Japanese Inpatients

Background

It has been reported that zinc deficiency is related to severe inflammatory conditions especially those of respiratory diseases. However, studies that have examined the association between the serum zinc concentration and the severity of coronavirus disease 2019 (COVID-19) are still limited. The aim of this study was to assess that association in Japanese inpatients with COVID-19.

Methods

This cross-sectional study, conducted from April 2020 to August 2021, included 467 eligible adult inpatients with COVID-19 whose serum zinc concentration was measured. Serum zinc concentration categories were defined as deficiency (< 60 μg/dL), marginal deficiency (≥ 60 to < 80 μg/dL), and normal (≥ 80 μg/dL). Multivariate logistic regression was used to assess the association between serum zinc deficiency and severe COVID-19. Serum zinc concentration levels were compared between mild and other severities of COVID-19 by Dunnett's method. The P for trend was estimated using the Jonckheere-Terpstra test.

Results

The proportions of subjects with serum zinc deficiency (< 60 μg/dL) and marginal zinc deficiency (≥ 60 to < 80 μg/dL) were 39.5% and 54.3% in women, and 36.4% and 57.0% in men, respectively. Serum zinc deficiency was significantly associated with severe COVID-19 compared to marginal deficiency and normal (odds ratio = 3.60, 95% confidence interval = 1.60-8.13, P < 0.01) after adjusting for confounders. An increase in severity of COVID-19 was inversely related to increases in serum zinc concentration levels (P < 0.01 for trend). Each serum zinc concentration of moderate and severe cases was also significantly lower compared with mild cases (P < 0.01).

Conclusion

The severity of COVID-19 was significantly related to serum zinc concentration levels. These results suggest the importance of considering the serum zinc concentration when treating patients with COVID-19.

The Challenge of Misleading Information: Does the Interaction between Zinc and Vitamin D Influence the Immune Response against SARS-CoV-2 in the Elderly Population?

Immunization is a challenge for the elderly population and can leave this group more vulnerable to opportunistic pathogens such as SARS-CoV-2. Due to this situation, while vaccines were in the development phase, hypotheses were raised about the role of vitamins and minerals in immunization. In Brazil, there was a controversy regarding the well-known COVID-19 Kit, a standardized prescription for positive cases that contained zinc, and vitamin D, and anti-parasitic drugs. There was great controversy in scientific circles, since COVID-19 brought a major challenge for health professionals and public authorities: misleading information. In this study, we evaluated the role of vitamin D and zinc in the production of anti-SARS-CoV-2 neutralizing antibodies (NAbs) in a group of elderly residents in a nursing home in northeastern Brazil. Serum levels of COVID-19 NAbs were assessed, along with vitamin D and zinc, in two phases. The first (T1) was in August 2022 with 26 elderly people, and the second (T2) was in March 2023 with 21, due to the death of five participants. Overall, we observed satisfactory levels for vitamin D, with no participants showing a deficiency in either test, and zinc, with only two participants having a negative result at T1 and three at T2. However, a drop in the average number of NAbs was observed, especially in women (T1 = 89 ± 19 vs. T2 = 57 ± 44), highlighting the importance of monitoring this immunological parameter in the population studied. Based on the results, we suggest that there is no synergism between the micronutrients studied and NAbs (p > 0.05). Further studies are needed to consolidate the findings of an absence of synergism between vitamin D and zinc in the maintenance of NAbs.

The interplay between oxidative stress, zinc, and metabolic dysfunction in polycystic ovarian syndrome

Polycystic ovarian syndrome (PCOS) is a functional endocrine disorder characterized by hyperandrogenism, ovulatory dysfunction, and polycystic ovarian morphology that has been associated with chronic disease and comorbidities including adverse metabolic and cardiac disorders. This review aims to evaluate the role of oxidative stress and zinc in the metabolic dysfunction observed in PCOS, with a focus on insulin resistance. Recent studies indicate that oxidative stress markers are elevated in PCOS and correlate with hyperandrogenemia, obesity, and insulin resistance. Zinc, an essential trace element, is crucial for metabolic processes, particularly in the pancreas for beta-cell function and glucagon secretion. Insufficient zinc levels have been linked to diabetes, obesity, and lipid metabolism disorders. This review aims to highlight the interplay between oxidative stress, zinc, and metabolic dysfunction in PCOS, suggesting that zinc supplementation could mitigate some metabolic and endocrine manifestations of PCOS.

The prevalence and risk factors associated with zinc deficiency after pancreatic surgery

PURPOSE

To clarify the prevalence, risk factors, and clinical implications associated with zinc deficiency in patients undergoing pancreatic surgery.

METHODS

The serum zinc levels were measured in 329 patients post-pancreatic surgery between January and April 2021. The postoperative serum zinc levels and clinicopathological variables were retrospectively analyzed.

RESULTS

The median serum zinc level was 73 µg/dL (33-218). Zinc deficiency (zinc level < 60 µg/dL) was observed in 52 patients (16%). A total of 329 patients were classified into zinc-deficient (n = 52) and non-deficient (zinc ≥ 60 µg/dL, n = 277) groups. A univariate analysis revealed significant differences in sex, postoperative body mass index, serum albumin, total cholesterol, creatinine, aspartate aminotransferase (AST), HbA1c levels, diabetes, surgical procedures, and operative blood loss. According to a multivariate analysis, male sex [odds ratio (OR) 3.70; 95% confidence interval (CI) 1.67-8.20; p = 0.001], postoperative serum albumin levels < 3.9 g/dL (OR 6.39; 95% CI 3.30-12.37; p < 0.001), postoperative serum AST ≥ 51 U/L (OR, 4.6; 95% CI 0.07-0.29; p < 0.001), and total pancreatectomy (OR 3.68; 95% CI 1.37-9.85; p = 0.009) were found to be independent predictors of zinc deficiency after pancreatic surgery.

CONCLUSIONS

Zinc deficiency frequently occurs in patients undergoing pancreatic surgery. Lower postoperative zinc levels could be linked to sex, the serum albumin and AST levels, and surgery type.

Subjective Symptoms and Disease Activity Related to Serum Zinc Concentration in Primary Sjögren's Syndrome

Background/Objectives: We examined the frequency of zinc deficiency in patients with Sjögren's syndrome (SS) and the relationship between zinc deficiency and each of the subjective symptoms and disease activity. Methods: We enrolled 164 patients aged ≥ 20 years with primary SS (pSS) based on the revised diagnostic criteria of the Ministry of Health, Labor and Welfare (1999) and 144 patients with RA diagnosed according to the ACR/EULAR classification criteria for RA (2010) as a comparison group. Subjective symptoms were confirmed using an original questionnaire, and disease activity was determined using the European League Against Rheumatism Sjögren's Syndrome Disease Activity Index (ESSDAI). The serum zinc concentrations were measured in both SS and RA patients. Results: The rate of zinc deficiency in the SS group was 26.1%, significantly higher than that in the RA group (7.6%). The rate of zinc deficiency was significantly higher in the pSS group compared with Japanese health checkup recipients reported in the literature. The mean serum zinc concentration in primary SS was 60.6 ± 7.3 µmol/L in the high disease activity group with an ESSDAI of ≥5 points, which was significantly lower than the concentration of 69.7 ± 10.2 µmol/L in patients with an ESSDAI of ≤4 points. Conclusions: The frequency of zinc deficiency was higher in patients with pSS than in patients with RA. Disease activity was also higher in patients with zinc deficiency, suggesting an association between zinc concentration and organ involvement in pSS.

Zinc Supplementation Reduces Testicular Cell Apoptosis in Mice and Improves Spermatogenic Dysfunction Caused by Marginal Zinc Deficiency

Zinc (Zn) is an important trace element in the human body and plays an important role in growth, development, and male reproductive functions. Marginal zinc deficiency (MZD) is common in the human population and can cause spermatogenic dysfunction in males. Therefore, the aim of this study was to investigate methods to improve spermatogenic dysfunction caused by MZD and to further explore its mechanism of action. A total of 75 4-week-old male SPF ICR mice were randomly divided into five groups (control, MZD, MZD + ZnY2, MZD + ZnY4, and MZD + ZnY8, 15 mice per group). The dietary Zn content was 30 mg/kg in the control group and 10 mg/kg in the other groups. From low to high, the Zn supplementation doses administered to the three groups were 2, 4, and 8 mg/kg·bw. After 35 days, the zinc content, sperm quality, activity of spermatogenic enzymes, oxidative stress level, and apoptosis level of the testes in mice were determined. The results showed that MZD decreased the level of Zn in the serum, sperm quality, and activity of spermatogenic enzymes in mice. After Zn supplementation, the Zn level in the serum increased, sperm quality was significantly improved, and spermatogenic enzyme activity was restored. In addition, MZD reduced the content of antioxidants (copper-zinc superoxide dismutase (Cu-Zn SOD), metallothionein (MT), and glutathione (GSH) and promoted malondialdehyde (MDA) production. The apoptosis index of the testis also increased significantly in the MZD group. After Zn supplementation, the level of oxidative stress decreased, and the apoptosis index in the testis was reduced. Furthermore, quantitative real-time polymerase chain reaction (qRT-PCR) showed that the expression of B-cell lymphoma-2 (Bcl-2) mRNA and Bcl-2/BCL2-associated X (Bax) in the control group decreased in testicular cells, and their expression was restored after Zn supplementation. The results of this study indicated that Zn supplementation can reduce the level of oxidative stress and increase the ability of testicular cells to resist apoptosis, thereby improving spermatogenic dysfunction caused by MZD in mice.

Demographic and clinical characteristics of patients with zinc deficiency: analysis of a nationwide Japanese medical claims database

Zinc deficiency, affecting more than 2 billion people globally, poses a significant public health burden due to its numerous unfavorable effects, such as impaired immune function, taste and smell disorders, pneumonia, growth retardation, visual impairment, and skin disorders. Despite its critical role, extensive large-scale studies investigating the correlation between patient characteristics and zinc deficiency still need to be completed. We conducted a retrospective, cross-sectional observational study using a nationwide Japanese claims database from January 2019 to December 2021. The study population included 13,100 patients with available serum zinc concentration data, excluding individuals under 20 and those assessed for zinc concentrations after being prescribed zinc-containing medication. Significant associations with zinc deficiency were noted among older adults, males, and inpatients. Multivariate analysis, adjusting for age and sex, indicated significant associations with comorbidities, including pneumonitis due to solids and liquids with an adjusted Odds Ratio (aOR) of 2.959; decubitus ulcer and pressure area (aOR 2.403), sarcopenia (aOR 2.217), COVID-19 (aOR 1.889), and chronic kidney disease (aOR 1.835). Significant association with medications, including spironolactone (aOR 2.523), systemic antibacterials (aOR 2.419), furosemide (aOR 2.138), antianemic preparations (aOR 2.027), and thyroid hormones (aOR 1.864) were also found. These results may aid clinicians in identifying patients at risk of zinc deficiency, potentially improving care outcomes.

Enhancing Nutritional Status and Addressing Micronutrient Deficiencies: Evaluating the Impact of Workplace Nutrition Program on Female Workers in Vietnam

This randomized controlled clinical study aimed to assess the effectiveness of a nutrition intervention program for non-pregnant female workers in Vietnam. A total of 500 female workers were randomly assigned to the intervention and control groups. Participants in the intervention group were provided nutrition education, personalized specific dietary, and received oral nutrition supplements (ONS)-which contained multi-minerals and vitamins according to recommendations for adults for a duration of 12 wk, while participants in the control group received only nutrition education. The result shows the percentage of malnutrition by BMI in the control group rose from 15.6% to 21.3% after 12 wk; the figure for counterpart experienced a remain unchanged (p<0.05). Additionally, the mean of serum zinc in the intervention group significantly increased from 49.0±21.2 μg/dL to 53.6±19.5 μg/dL after 12 wk. Moreover, the intervention group demonstrated significant increases in serum iron and total serum calcium levels (p<0.05), with from 13.9±5.6 μmol/L to 15.3±5.8 μmol/L, and from 2.36±0.15 mmol/L to 2.4±0.09 mmol/L, respectively. The participants of the intervention group were more likely to have higher total serum calcium (Coef=0.04, p<0.05), serum iron (Coef=1.99, p<0.05), and serum zinc (Coef=18.9, p<0.05), which presents a reduce micronutrient deficiency. In conclusion, workplace nutrition interventions effectively mitigate micronutrient deficiencies and improve the nutritional status of female workers.

Prospective observational study of zinc deficiency symptoms during first-line chemotherapy for gastric and colorectal cancer

Background

Zinc deficiency during long-term chemotherapy and its related symptoms, including skin rash, taste disorders, and oral mucositis, have not been sufficiently investigated.

Methods

This prospective observational study enrolled patients with gastric and colorectal cancer who underwent standard first-line chemotherapy. According to the Practice Guidelines for Zinc Deficiency, zinc deficiency is defined as a serum level of <60 µg/dL. Serum zinc levels were measured before and after (1, 3, and 6 months) chemotherapy, and symptoms were assessed using the Patient-Reported Outcomes version of the Common Terminology Criteria for Adverse Events version 1.0. Repeated measures were analyzed using a generalized linear mixed model.

Results

Of the 61 enrolled patients, 48 who underwent standard first-line chemotherapy with fluoropyrimidine plus oxaliplatin were analyzed. Zinc deficiency was observed in 18 patients (38%) before chemotherapy. The least-squares means of serum zinc levels significantly decreased at 3 and 6 months of chemotherapy in 30 patients without zinc deficiency at the start of chemotherapy (both P<0.01) but not in 18 with zinc deficiency at the beginning. Changes in serum zinc levels during chemotherapy negatively correlated with changes in taste, rash, and itching (all P<0.04) in patients without zinc deficiency before treatment initiation.

Conclusions

Serum zinc levels decreased during chemotherapy in zinc-non-deficient patients at the beginning of chemotherapy and correlated with taste changes, skin rash, and itching. Therefore, investigating whether zinc supplementation ameliorates these symptoms is necessary.

Characteristics of Zn Content and Localization, Cu-Zn SOD, and MT Levels in the Tissues of Marginally Zn-Deficient Mice

Zinc (Zn) is an important trace element in the human body, and Zn deficiency affects the Zn content of major tissues. Marginal Zn deficiency is more common than severe Zn deficiency in humans. The objective of the present study was to compare the content and distribution of Zn and the change in the copper (Cu)-Zn superoxide dismutase (SOD) and metallothionein (MT) levels of soft tissues. Mice were fed with 30 mg/kg (control) or 10 mg/kg (marginally Zn-deficient, MZD) Zn diet for 35 days. We observed that only the Zn contents of serum, bones, and muscles in the control group were higher than those in the MZD group. Autometallography (AMG) was used as a method for staining Zn ions, and the semi-quantitative result indicated that the AMG products of the liver, duodenum, heart, lung, testes, and epididymis in the control group were higher than those in the MZD group. Furthermore, the contents of MT and the activities of Cu-Zn SOD in the testes, brain, duodenum, and liver were higher in the control group than those in the MZD group. However, the AMG products and the activities of Cu-Zn SOD of the kidney in the MZD group were more/higher than those in the control group. These results indicated that a change in the total Zn content of soft tissues may be not obvious and insensitive, and thus, more attention should be given to the distribution and localization of Zn ions. The functional indicators, MT and Cu-Zn SOD, are suitable biomarkers for evaluating zinc nutritional status. The brain, testes, duodenum, and liver are susceptive organs to Zn deficiency.

Evaluation of the serum zinc concentration in male infertility patients: an analysis of 2010 cases

Zinc is an important trace element, and its importance for male infertility has been reported. The aim of the study was to assess whether the serum zinc concentrations were related to semen quality in male infertility patients. In 2010 subjects who consulted at our male infertility clinic between November 2018 and May 2021, serum zinc concentrations were assessed along with age, sperm concentration, sperm motility, endocrine panel, and body mass index (BMI). A normal zinc concentration was observed in 1069 (53.2%), subclinical deficiency in 845 (42.0%), and deficiency in 79 subjects (3.9%). On the other hand, high a zinc level was observed in only 17 subjects (0.9%). The serum zinc concentration did not relate with age, sperm concentration, sperm motility, luteinizing hormone (LH), follicle stimulating hormone (FSH), testosterone, and body mass index (BMI). However, normozoospermic subjects showed significantly higher zinc concentrations than among azoospermic (included non-obstructive; NOA and obstructive; OA) and cryptozoospermic patients. Furthermore, the zinc concentration was lower in NOA subjects when comparing to oligozoospermia and/or asthenozoospermia. An association between zinc concentration and semen analysis remained unclear. This study was cross-sectional and retrospective, however, this is a largest investigation of the zinc concentration during reproductive life span in Japan. Further accumulation of cases are required to further examine the potential relationship between zinc concentration and semen quality.

Serum Zinc and Long-Term Prognosis after Acute Traumatic Brain Injury with Intracranial Injury: A Multicenter Prospective Study

Serum zinc levels in the acute stages after traumatic brain injury (TBI) may be capable of predicting cinical and functional prognoses. This study aimed to evaluate the association between serum zinc levels and long-term survival and neurological outcomes in TBI patients with intracranial injury. This multicenter prospective cohort study enrolled adult TBI patients with intracranial injury who visited emergency departments between December 2018 and June 2020. Serum zinc levels drawn within 24 h after injury were categorized into four groups: low (<80.0 mcg/dL), low−normal (80.0−100.0 mcg/dL), high−normal (100.1−120.0 mcg/dL), and high (>120.0 mcg/dL). The study outcomes were 6-month mortality and disability (Glasgow Outcome Scale, 1−3). A multilevel multivariable logistic regression analysis was conducted to estimate associations between serum zinc and study outcomes. From the eligible TBI patients (N = 487), the median (interquartile range) serum zinc level was 112.0 mcg/dL (95.0−142.0). Six-month mortality and disability were 21.1% (103/487) and 29.6% (144/487), respectively. Compared to the high−normal zinc group, there were significant associations with 6-month mortality and disability observed in the low zinc group (aORs (95% CIs): 1.91 (1.60−2.28) and 1.95 (1.62−2.36) for the low group; 1.14 (0.67−1.94) and 1.15 (0.91−1.46) for the low−normal group; and 0.72 (0.44−1.16) and 0.88 (0.61−1.27) for the high group, respectively). Among the 122 TBI patients with diabetes mellitus, the low zinc group showed a higher incidence of 6-month mortality (aOR (95% CI): 9.13 (4.01−20.81)) compared to the high−normal zinc group. Moreover, the low and low−normal groups had higher odds for 6-month disability (aORs (95% CIs): 6.63 (3.61−12.15) for the low group and 2.37 (1.38−4.07) for the low−normal group). Serum zinc deficiency is associated with a higher incidence of 6-month mortality and disability after injury for TBI patients with intracranial injury.

Marginal Zinc Deficiency in Mice Increased the Number of Abnormal Sperm and Altered the Expression Level of Spermatogenesis-Related Genes

Marginal zinc deficiency is more common than severe zinc deficiency, and the effect of marginal zinc deficiency on male reproduction is unknown. This study investigated the effect of marginal zinc deficiency on spermatogenesis and its mechanism. Male ICR mice were fed normal zinc (30 mg/kg) and marginal zinc deficiency (10 mg/kg) diets for 35 days. Zinc-dependent proteins and enzymes were measured as biomarkers of zinc levels in the body. Metallothionein and Cu-Zn SOD levels in the control group were higher than those in the marginal zinc deficiency group. Hematoxylin and eosin staining showed that the marginal zinc deficiency diet caused histopathological changes in the testis and destruction of the sperm head under scanning electron microscopy. Sperm parameters and sex hormone levels were also affected by marginal zinc deficiency. In addition, marginal zinc deficiency led to alter expression level of several important spermatogenesis-related genes in the epididymis and testes. These results indicate that although zinc intake in marginal zinc deficiency is close to the recommended reference value, low zinc intake interferes with the expression of genes related to spermatogenesis and may lead to sperm abnormalities in mice.

Clinical Significance of Serum Zinc Levels on the Development of Sarcopenia in Cirrhotic Patients

BACKGROUND/AIM

Sarcopenia increases the mortality in patients with cirrhosis. Approximately 60% of zinc is accumulated in skeletal muscle. We aimed to determine the role of subclinical zinc deficiency on sarcopenia development in patients with cirrhosis.

PATIENTS AND METHODS

We enrolled 151 patients with cirrhosis and divided them into the group with normal serum zinc levels (Group N: 80-130 μg/dl; n=38) and group with subclinical zinc deficiency (Group D: <80 μg/dl; n=113). The risk factors for sarcopenia were then investigated.

RESULTS

Group D had more sarcopenia cases than Group N (31.0% vs. 13.2%). In group D, HGS exhibited a weakly positive but significant correlation with serum zinc levels (R=0.287, p=0.00212), serum zinc levels negatively correlated with both ammonia and myostatin levels (R=-0.254, p=0.0078; R=-0.33, p<0.01), and low zinc levels were independently associated with sarcopenia development.

CONCLUSION

Patients with cirrhosis showing subclinical zinc deficiency have a significantly higher risk of developing sarcopenia.

Gustatory and Saliva Secretory Dysfunctions in COVID-19 Patients with Zinc Deficiency

Given the ever-progressing studies on coronavirus disease 2019 (COVID-19), it is critical to update our knowledge about COVID-19 symptomatology and pathophysiology. In the present narrative review, oral symptoms were overviewed using the latest data and their pathogenesis was hypothetically speculated. PubMed, LitCovid, ProQuest, and Google Scholar were searched for relevant studies from 1 April 2021 with a cutoff date of 31 January 2022. The literature search indicated that gustatory dysfunction and saliva secretory dysfunction are prevalent in COVID-19 patients and both dysfunctions persist after recovery from the disease, suggesting the pathogenic mechanism common to these cooccurring symptoms. COVID-19 patients are characterized by hypozincemia, in which zinc is possibly redistributed from blood to the liver at the expense of zinc in other tissues. If COVID-19 induces intracellular zinc deficiency, the activity of zinc-metalloenzyme carbonic anhydrase localized in taste buds and salivary glands may be influenced to adversely affect gustatory and saliva secretory functions. Zinc-binding metallothioneins and zinc transporters, which cooperatively control cellular zinc homeostasis, are expressed in oral tissues participating in taste and saliva secretion. Their expression dysregulation associated with COVID-19-induced zinc deficiency may have some effect on oral functions. Zinc supplementation is expected to improve oral symptoms in COVID-19 patients.

Minerals and Cancer: Overview of the Possible Diagnostic Value

Cancer is the second leading cause of death worldwide and is expected to increase by one-third over the next two decades, in parallel with the growing proportion of the elderly population. Treatment and control of cancer incidence is a global issue. Since there is no clear way to prevent or cure this deadly malignancy, diagnostic, predictive, and prognostic markers for oncological diseases are of great therapeutic value. Minerals and trace elements are important micronutrients for normal physiological function of the body. They are abundant in natural food sources and are regularly included in dietary supplements whereas highly processed industrial food often contains reduced or altered amounts of them. In modern society, the daily intake, storage pools, and homeostasis of these micronutrients are dependent on certain dietary habits and can be thrown out of balance by malignancies. The current work summarizes the data on minerals and trace elements associated with abnormal accumulation or depletion states in tumor patients and discusses their value as potential tumor-associated biomarkers that could be introduced into cancer therapy.

Serum zinc levels and in vivo beta-amyloid deposition in the human brain

Background

Despite the known associations between zinc levels and Alzheimer’s disease (AD) dementia and related cognitive impairment, the underlying neuropathological links remain poorly understood. We tested the hypothesis that serum zinc level is associated with cerebral beta-amyloid protein (Aβ) deposition. Additionally, we explored associations between serum zinc levels and other AD pathologies [i.e., tau deposition and AD-signature cerebral glucose metabolism (AD-CM)] and white matter hyperintensities (WMHs), which are measures of cerebrovascular injury.

Methods

A total of 241 cognitively normal older adults between 55 and 90 years of age were enrolled. All the participants underwent comprehensive clinical assessments, serum zinc level measurement, and multimodal brain imaging, including Pittsburgh compound B-positron emission tomography (PET), AV-1451 PET, fluorodeoxyglucose (FDG)-PET, and magnetic resonance imaging. Zinc levels were stratified into three categories: < 80 μg/dL (low), 80 to 90 μg/dL (medium), and > 90 μg/dL (high).

Results

A low serum zinc level was significantly associated with increased Aβ retention. In addition, apolipoprotein E ε4 allele (APOE4) status moderated the association: the relationship between low zinc level and Aβ retention was significant only in APOE4 carriers. Although a low zinc level appeared to reduce AD-CM, the relationship became insignificant on sensitivity analysis including only individuals with no nutritional deficiency. The serum zinc level was associated with neither tau deposition nor the WMH volume.

Conclusions

Our findings suggest that decreased serum zinc levels are associated with elevation of brain amyloid deposition. In terms of AD prevention, more attention needs to be paid to the role of zinc.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13195-021-00931-3.

Zinc Deficiency, Plasma Fatty Acid Profile and Desaturase Activities in Hemodialysis Patients: Is Supplementation Necessary?

Background: Desaturation and elongation are critical processes in endogenous metabolic fatty acid pathways. Zinc (Zn) is a cofactor for desaturases and elongases enzymes. There is limited evidence regarding the relationships between biomarkers of Zn status, nutritional intake, plasma phospholipid fatty acid profile and clinical outcomes among patients undergoing hemodialysis (HD). Objective: To examine the relationships between dietary and serum levels of Zn and Cu/Zn ratio and to explore associations of these micronutrients with PUFA profile and estimated desaturase and elongase enzyme activities in serum phospholipids among HD patients. Methods: This study included 40 adult patients undergoing hemodialysis treatment. Repeated 24-h recalls were applied for dietary intake assessment. Serum concentration of Zn and Cu were determined using inductively coupled plasma mass spectrometry and fatty acid composition by gas-liquid chromatography. Desaturase and elongase activities were calculated from product-precursor fatty acid ratios. Results: Inadequate dietary Zn intake was found in 55% of HD patients. They all had serum Zn concentration below the reference value of 60 μg/dL (mean 38.8 ± 7.72 μg/dL). Adequate zinc intake was accompanied with significantly higher intake of energy, total fats, SFA, MUFA and proteins. There was no correlation between Zn serum status and Zn intake estimates. Serum Cu/Zn ratio was high, (2.76 ± 0.68), directly and significantly associated with HD period, CRP, BMI, VFA, and inversely with Kt/V, albumin, iron, and iPTH. The n-6/n-3 ratio in plasma phospholipids was elevated (12.25 ± 3.45) and patients with inadequate Zn intake had lower n-3 PUFA intake and status compared to those with adequate intake. Serum Zn concentrations were inversely correlated with linoleic/dihomo-γ-linolenic acid ratio (LA/DGLA) (p = 0.037), related to D6-desaturase activity (p = 0.033) and directly with DGLA relative abundances (p = 0.024). Cu status was inversely associated with EPA level (p = 0.03) and estimates of elongase activity (p = 0.001). Furthermore, positive relationship was found between the Cu/Zn ratio and determined elongase value (p = 0.01). Conclusion: Findings of this study underpin the high prevalence of Zn deficiency and inadequate n-3 PUFA intake and status among subjects undergoing HD. The results obtained indicate that the assessment of Zn status should be a standard parameter of nutritional status screening in HD patients while emphasizing the importance of Cu/Zn determination. Although further research is warranted, Zn and-n-3 PUFA supplementation in HD patients might be beneficial for the prevention and attenuation of adverse health outcomes.

Possible involvement of zinc deficiency in epidermal growth factor receptor inhibitor-induced xerotic dermatitis

Cancer treatment with epidermal growth factor receptor inhibitors (EGFRIs) often induces severe xerotic dermatitis. Various irritants facilitate development of dermatitis in xerotic skin. As zinc deficiency plays a role in the development of irritant dermatitis, we measured serum zinc levels in 25 patients with xerotic dermatitis due to treatment with EGFRIs. Of these patients, nine were treated with EGFR tyrosine kinase inhibitors and 16 were treated with anti-EGFR antibody alone or in combination with other anticancer agents. Serum zinc levels of all patients were lower than the normal range of >80 μg/dL, with a mean ± SD serum zinc level of 56.4 ± 11.7 μg/dL. These were correlated with serum magnesium levels in patients. As the serum magnesium level is known to be reduced by the inhibition of EGFR, a similar mechanism may also be involved in decreasing the serum zinc level. Among 21 patients treated with zinc supplementation for more than 2 months, xerotic dermatitis markedly improved, with an increase of serum zinc levels in 16 patients. The other five patients exhibited no significant improvement in their skin condition, and insufficient and unstable increase in serum zinc levels. In conclusion, zinc supplementation may be beneficial in supportive care for patients with EGFRI-induced xerotic dermatitis.

Zinc

Since the discovery of manifest Zn deficiency in 1961, the increasing number of studies demonstrated the association between altered Zn status and multiple diseases. In this chapter, we provide a review of the most recent advances on the role of Zn in health and disease (2010-20), with a special focus on the role of Zn in neurodegenerative and neurodevelopmental disorders, diabetes and obesity, male and female reproduction, as well as COVID-19. In parallel with the revealed tight association between ASD risk and severity and Zn status, the particular mechanisms linking Zn2+ and ASD pathogenesis like modulation of synaptic plasticity through ProSAP/Shank scaffold, neurotransmitter metabolism, and gut microbiota, have been elucidated. The increasing body of data indicate the potential involvement of Zn2+ metabolism in neurodegeneration. Systemic Zn levels in Alzheimer's and Parkinson's disease were found to be reduced, whereas its sequestration in brain may result in modulation of amyloid β and α-synuclein processing with subsequent toxic effects. Zn2+ was shown to possess adipotropic effects through the role of zinc transporters, zinc finger proteins, and Zn-α2-glycoprotein in adipose tissue physiology, underlying its particular role in pathogenesis of obesity and diabetes mellitus type 2. Recent findings also contribute to further understanding of the role of Zn2+ in spermatogenesis and sperm functioning, as well as oocyte development and fertilization. Finally, Zn2+ was shown to be the potential adjuvant therapy in management of novel coronavirus infection (COVID-19), underlining the perspectives of zinc in management of old and new threats.