Effects of zinc deficiency on immune functions

Green strength: The role of micronutrients in plant-based diets for athletic performance enhancement

This review examines the correlation between plant-based diets and athletic performance, with a specific emphasis on the vital aspect of optimizing micronutrients for athletes. In light of the increasing prevalence of plant-based nutrition among athletes due to its perceived advantages in terms of health, ethics, and the environment, this study investigates the ability of these diets to satisfy the demanding nutritional requirements essential for achieving optimal performance and facilitating recovery. The article emphasizes the significance of essential micronutrients such as iron, vitamin B12, calcium, vitamin D, zinc, and omega-3 fatty acids and also addressing the challenges with their absorption and bioavailability from plant sources. The review consolidates existing scientific knowledge to propose strategies for improving micronutrient consumption, comparing the effects of supplements against whole foods, and highlighting the significance of enhancing bioavailability. The proposal supports the implementation of personalized meal planning, with the assistance of sports nutritionists or dietitians, and is substantiated by case studies showcasing the success of plant-based athletes. Future research directions examine the long-term effects of plant-based diets on micronutrient status and athletic performance, as well as developing nutritional trends and technology. The review concludes that plant-based diets can meet athletes' nutritional demands and improve peak performance while aligning with personal and ethical values with strategic planning and professional guidance. This study intends to help athletes, coaches, and nutritionists understand plant-based nutrition for enhanced athletic performance.

Clinically proven natural products, vitamins and mineral in boosting up immunity: A comprehensive review

BACKGROUND

and Purposes: The terminology "immune boost-up" was the talk of the topic in this Covid-19 pandemic. A significant number of the people took initiative to increase the body's defense capacity through boosting up immunity worldwide. Considering this, the study was designed to explain the natural products, vitamins and mineral that were proved by clinical trail as immunity enhancer.

METHODS

Information was retrieved from SciVerse Scopus ® (Elsevier Properties S. A, USA), Web of Science® (Thomson Reuters, USA), and PubMed based on immunity, nutrients, natural products in boosting up immunity, minerals and vitamins in boosting up immunity, and immune booster agents.

RESULT

A well-defined immune cells response provide a-well functioning defense system for the human physiological system. Cells of the immune system must require adequate stimulation so that these cells can prepare themselves competent enough to fight against any unintended onslaught. Several pharmacologically active medicinal plants and plants derived probiotics or micronutrients have played a pivotal role in enhancing the immune boost-up process. Their role has been well established from the previous study. Immune stimulating cells, especially cells of acquired immunity are closely associated with the immune-boosting up process because all the immunological reactions and mechanisms are mediated through these cells.

CONCLUSION

This article highlighted the mechanism of action of different natural products, vitamins and mineral in boosting up the immunity of the human body and strengthening the body's defense system. Therefore, it is recommended that until the specific immune-boosting drugs are available in pharma markets, anyone can consider the mentioned products as dietary supplements to boost up the immunity.

The effect of Vitamin C and Zn supplementation on the immune system and clinical outcomes in COVID-19 patients

SARS-CoV-2 (Severe Acute Respiratory Syndrome-Coronavirus-2) is the most dangerous form of the coronavirus, which causes COVID-19. In patients with severe COVID-19, the immune system becomes markedly overactive. There is evidence that supplementation with select micronutrients may play a role in maintaining immune system function in this patient population. Throughout the COVID-19 pandemic, significant emphasis has been placed on the importance of supplementing critical micronutrients such as Vitamin C and Zinc (Zn) due to their immunomodulatory effects. Viral infections, like COVID-19, increase physiological demand for these micronutrients. Therefore, the purpose of this review was to provide comprehensive information regarding the potential effectiveness of Vitamin C and Zn supplementation during viral infection and specifically COVID-19. This review demonstrated a relation between Vitamin C and Zn deficiency and a reduction in the innate immune response, which can ultimately make patients with COVID-19 more vulnerable to viral infection. As such, adequate intake of Vitamin C and Zn, as an adjunctive therapeutic approach with any necessary pharmacological treatment(s), may be necessary to mitigate the adverse physiological effects of COVID-19. To truly clarify the role of Vitamin C and Zn supplementation in the management of COVID-19, we must wait for the results of ongoing randomized controlled trials. The toxicity of Vitamin C and Zn should also be considered to prevent over-supplementation. Over-supplementation of Vitamin C can lead to oxalate toxicity, while increased Zn intake can reduce immune system function. In summary, Vitamin C and Zn supplementation may be useful in mitigating COVID-19 symptomology.

Serum Free Zinc Is Associated With Vaccination Response to SARS-CoV-2

Background

Zinc (Zn) is an essential trace element with high relevance for the immune system, and its deficiency is associated with elevated infection risk and severe disease course. The association of Zn status with the immune response to SARS-CoV-2 vaccination is unknown.

Methods

A cohort of adult health care workers (n=126) received two doses of BNT162B2, and provided up to four serum samples over a time course of 6 months. Total SARS-CoV-2 IgG and neutralizing antibody potency was determined, along with total as well as free Zn concentrations.

Results

The SARS-CoV-2 antibodies showed the expected rise in response to vaccination, and decreased toward the last sampling point, with highest levels measured three weeks after the second dose. Total serum Zn concentrations were relatively stable over time, and showed no significant association with SARS-CoV-2 antibodies. Baseline total serum Zn concentration and supplemental intake of Zn were both unrelated to the antibody response to SARS-CoV-2 vaccination. Time resolved analysis of free Zn indicated a similar dynamic as the humoral response. A positive correlation was observed between free Zn concentrations and both the induced antibodies and neutralizing antibody potency.

Conclusion

While the biomarkers of Zn status and supplemental Zn intake appeared unrelated to the humoral immune response to SARS-CoV-2 vaccination, the observed correlation of free Zn to the induced antibodies indicates a diagnostic value of this novel biomarker for the immune system.

New Insights into the Role of Trace Elements in IBD

Micronutrient deficiencies are common in inflammatory bowel disease and have clinical impact, being both a sign of complicated disease and a cause of morbidity. The involved systemic inflammatory response is responsible for altering the concentration of a wide range of trace elements in the serum, including zinc and selenium. This review summarizes recent advances and evidence-based knowledge regarding the impact of selenium and zinc on oxidative stress and microbiota changes in IBD patients. Getting new insight into the impact of malnutrition, particularly on the micronutrients' impact on the development, composition, and metabolism of microbiota, as well as the influence of oxidative stress and the mucosal immune response, could help in implementing new management strategies for IBD patients, with focus on a more integrated approach.

Zinc supplementation for the treatment of measles in children

BACKGROUND

Measles is an important cause of childhood morbidity and mortality globally, despite increasing vaccine coverage. Zinc plays a significant role in the maintenance of normal immunological functions, therefore supplements given to zinc-deficient children will increase the availability of zinc and could reduce measles-related morbidity and mortality. This is an update of a review first published in 2015.

OBJECTIVES

To assess the effects of zinc supplementation in reducing morbidity and mortality in children with measles.

SEARCH METHODS

We searched CENTRAL (03 February 2017, Issue 2), MEDLINE (1946 to 03 February 2017), Embase (1974 to 03 February 2017), CINAHL (1981 to 03 February 2017), LILACS (1982 to 03 February 2017), Web of Science (1985 to 03 February 2017), and BIOSIS Previews (1985 to 27 June 2014). We also searched ClinicalTrials.gov, the Australian New Zealand Clinical Trials Registry and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) on 03 February 2017 to identify unpublished and ongoing studies.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and quasi-RCTs evaluating the effects of zinc in reducing morbidity and mortality in children with measles.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the studies for inclusion and extracted data on outcomes, details of the interventions, and other study characteristics using a standardised data extraction form. We used risk ratio (RR) and hazard ratio (HR) as measures of effect with 95% confidence intervals (CI). We included only one study, and did not conduct meta-analysis.

MAIN RESULTS

We did not identify any new studies for inclusion in this update. One RCT met our inclusion criteria. The study was conducted in India and included 85 children diagnosed with measles and pneumonia. The trial showed no significant difference in mortality between children with measles and pneumonia who received zinc supplements and those who received placebo (RR 0.34, 95% CI 0.01 to 8.14). There was no significant difference in time to absence of fever between children who received zinc supplements and those who did not (HR 1.08, 95% CI 0.67 to 1.74). No treatment-related side effects were reported in either group. We assessed the overall quality of the evidence as very low.

AUTHORS' CONCLUSIONS

We could not draw any definitive conclusions from this review about the effects of zinc supplementation on clinical outcomes of children with measles due to the very low quality of the evidence available. There is insufficient evidence to confirm or refute the effect of zinc supplementation in children with measles.

Evaluation of Serum Trace Element Levels and Superoxide Dismutase Activity in Patients with Inflammatory Bowel Disease: Translating Basic Research into Clinical Application

The relationship of minerals and trace elements with inflammatory bowel disease (IBD) is complex. Alterations in their metabolism can be induced by the diseases and their complications. To study the role of trace elements in IBD patients' serum zinc and copper and their related enzymes, including superoxide dismutase (SOD), activity were measured in patients with IBD patients as well as in healthy subjects. In addition, the correlation between serum trace element levels, albumin, total protein, urea level, copper/zinc ratio, and disease activity (DA) was determined in these subjects. Serum samples were obtained from 35 patients (19 ulcerative colitis (UC) and 16 Crohn's disease (CD)) in the active phase of the disease and 30 healthy control subjects. Serum levels of zinc, copper, SOD activity, albumin, total protein, and urea were measured. The results were compared between the two groups using independent Student's t test in statistical analysis. Serum levels of zinc, SOD activity, albumin, and total protein were significantly lower (P < 0.05) in patients than controls, while serum urea level was significantly higher in patients compared to controls. Copper concentrations did not differ between patients with IBD (mean ± SD, 58.8 ± 20.7 μg/d) and controls (55.57 ± 12.6 μg/d). Decreased levels of zinc and SOD activity are associated with increased inflammatory processes indicating inappropriate antioxidant system in patients with IBD. Additionally, lower levels of albumin and total protein with higher level of urea reflect metabolic problems in liver system.

Transition Metal Homeostasis in Streptococcus pyogenes and Streptococcus pneumoniae

Trace metals such as Fe, Mn, Zn and Cu are essential for various biological functions including proper innate immune function. The host immune system has complicated and coordinated mechanisms in place to either starve and/or overload invading pathogens with various metals to combat the infection. Here, we discuss the roles of Fe, Mn and Zn in terms of nutritional immunity, and also the roles of Cu and Zn in metal overload in relation to the physiology and pathogenesis of two human streptococcal species, Streptococcus pneumoniae and Streptococcus pyogenes. S. pneumoniae is a major human pathogen that is carried asymptomatically in the nasopharynx by up to 70% of the population; however, transition to internal sites can cause a range of diseases such as pneumonia, otitis media, meningitis and bacteraemia. S. pyogenes is a human pathogen responsible for diseases ranging from pharyngitis and impetigo, to severe invasive infections. Both species have overlapping capacity with respect to metal acquisition, export and regulation and how metal homeostasis relates to their virulence and ability to invade and survive within the host. It is becoming more apparent that metals have an important role to play in the control of infection, and with further investigations, it could lead to the potential use of metals in novel antimicrobial therapies.

BILL E. KUNKLE INTERDISCIPLINARY BEEF SYMPOSIUM: Impact of mineral and vitamin status on beef cattle immune function and health

The importance of optimal mineral and vitamin nutrition on improving immune function and health has been recognized in the preceding decades. In the southeast, beef cattle are raised predominantly on forages that may be limiting in nutrients for optimal health, especially trace minerals such as Cu, Zn, and Se. Clinical deficiencies of these nutrients produce classic symptoms that are common to several nutrient deficiencies (e.g., slow growth and unthrifty appearance); however, subclinical deficiencies are more widespread and more difficult to detect, yet may result in broader economic losses. Dietary mineral concentrations often considered adequate for maximum growth, reproductive performance, or optimal immune function have been found to be insufficient at times of physiological stress (weaning, transport, comingling, etc.), when feed intake is reduced. The impacts of these deficiencies on beef cattle health are not apparent until calves have been subjected to these stressors. Health problems that are exacerbated by mineral or vitamin deficiencies include bovine respiratory disease, footrot, retained placenta, metritis, and mastitis. Many micronutrients have antioxidant properties through being components of enzymes and proteins that benefit animal health. In dairy cattle, high levels of supplemental Zn are generally associated with reduced somatic cell counts and improved foot health, possibly reflecting the importance of Zn in maintaining effective epithelial barriers. Neutrophils isolated from ruminants deficient in Cu or Se have reduced ability to kill ingested bacteria in vitro. Supplemental vitamin E, in its role as an intracellular antioxidant has been shown to decrease morbidity in stressed calves. There is more understanding of the important biological role that these nutrients play in the functioning of the complex and multifaceted immune system. However, there is still much to be learned about determining the micronutrient status of herds (and hence when supplementation will be beneficial), requirements for different genetic and environmental conditions, understanding the bioavailability of these nutrients from feedstuffs and forages, quantifying the bioavailability of different supplemental sources of these nutrients, and identifying the impact of dietary antagonists on these nutrients.

Zinc bioavailability in rats fed a plant-based diet: a study of fermentation and zinc supplementation

BACKGROUND

Zinc deficiency is a significant problem, in developing countries and in vegetarians, which can be caused by plant-based diets. Thus, dietary strategies, such as fermentation, to improve zinc bioavailability of diets should be investigated.

OBJECTIVE

To improve zinc bioavailability in a plant-based diet by the inclusion of fermented food.

DESIGN

Cassava tubers were fermented and made to replace the unfermented cassava in a basal plant-based diet, and compared with plant-based diets with and without zinc supplement. The zinc bioavailability of the diets was evaluated in Wistar rats that were fed these diets for 28 days. The evaluation was for zinc apparent absorption (ZnAA), serum zinc levels, and zinc deposits in liver and femur; in addition, the feed efficiency ratio (FER) of the diets and femur weight (FW) of the rats were evaluated.

RESULTS

During the cassava fermentation, lactic acid increased and pH decreased (from 6.8 to 3.9), which is favorable for native phytase activity, resulting in a 90.2% reduction of phytate content in cassava. The diet containing fermented cassava showed significantly higher levels of ZnAA, FER, and FW (p<0.001). Moreover, the zinc levels in serum and femur were significantly higher (p<0.001) compared with the results of the diet with unfermented cassava. The results clearly show a higher zinc bioavailability in the diet containing fermented cassava and are comparable with the results obtained with the plant-based diet with zinc supplement.

CONCLUSIONS

In conclusion, the fermentation of cassava reduces the phytate content. The diet containing the fermented cassava represents a better nutritional alternative than the diet with unfermented cassava and is comparable with the zinc-supplemented diets.

Zinc supplementation for the treatment of measles in children

BACKGROUND

Measles is still an important cause of childhood morbidity and mortality globally, despite increasing vaccine coverage. Zinc plays a significant role in the maintenance of normal immunological functions, therefore supplements given to zinc-deficient children will increase the availability of zinc and could reduce measles-related morbidity and mortality.

OBJECTIVES

To assess the effects of zinc supplementation in reducing morbidity and mortality in children with measles.

SEARCH METHODS

We searched CENTRAL (2014, Issue 5), MEDLINE (1946 to June week 3, 2014), EMBASE (1974 to June 2014), CINAHL (1981 to June 2014), LILACS (1982 to June 2014), Web of Science (1985 to June 2014) and BIOSIS Previews (1985 to June 2014). We also searched ClinicalTrials.gov and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) to identify unpublished and ongoing studies.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and quasi-RCTs evaluating the effects of zinc in reducing morbidity and mortality in children with measles.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the studies for inclusion and extracted data on outcomes, details of the interventions and other study characteristics using a standardised data extraction form. We used the risk ratio (RR) and hazard ratio as measures of effect with 95% confidence intervals (CI). We included only one study and we did not conduct any meta-analysis.

MAIN RESULTS

One RCT met our inclusion criteria. The study was conducted in India and included 85 children diagnosed with measles and pneumonia. The trial showed that there was no significant difference in mortality between the two groups (risk ratio (RR) 0.34, 95% confidence interval (CI) 0.01 to 8.14). Also, there was no significant difference in time to absence of fever between the two groups (hazard ratio (HR) 1.08, 95% CI 0.67 to 1.74). No treatment-related side effects were reported in either group. The overall quality of the evidence can be described as very low.

AUTHORS' CONCLUSIONS

We cannot draw any definite conclusions from this review about the effects of zinc supplementation on clinical outcomes of children with measles due to the very low quality of the evidence available. There is insufficient evidence to confirm or refute the effect of zinc supplementation in measles.

Undernutrition, the acute phase response to infection, and its effects on micronutrient status indicators

Infection and undernutrition are prevalent in developing countries and demonstrate a synergistic relation. Undernutrition increases infection-related morbidity and mortality. The acute phase response (APR) is an innate, systemic inflammatory reaction to a wide array of disruptions in a host's homeostasis, including infection. Released from immune cells in response to deleterious stimuli, proinflammatory cytokines act on distant tissues to induce behavioral (e.g., anorexia, weakness, and fatigue) and systemic effects of the APR. Cytokines act to increase energy and protein requirements to manifest fever and support hepatic acute phase protein (APP) production. Blood concentrations of glucose and lipid are augmented to provide energy to immune cells in response to cytokines. Additionally, infection decreases intestinal absorption of nutrients and can cause direct loss of micronutrients. Traditional indicators of iron, zinc, and vitamin A status are altered during the APR, leading to inaccurate estimations of deficiency in populations with a high or unknown prevalence of infection. Blood concentrations of APPs can be measured in nutrition interventions to assess the time stage and severity of infection and correct for the APR; however, standardized cutoffs for nutrition applications are needed. Protein-energy malnutrition leads to increased gut permeability to pathogens, abnormal immune cell populations, and impaired APP response. Micronutrient deficiencies cause specific immune impairments that affect both innate and adaptive responses. This review describes the antagonistic interaction between the APR and nutritional status and emphasizes the need for integrated interventions to address undernutrition and to reduce disease burden in developing countries.

Effect of zinc on human IgG1 and its FcγR interactions

In the present study, we show that histidines 310 and 435 at the CH2-CH3 interface of the Fc portion of human IgG1 can coordinate a Zn2+ and participate in the control of the CH2-CH2 interdomain opening. Structures obtained in the absence of Zn2+ have a reduced interdomain gap that likely hamper FcγR binding. This closed conformation of the Fc is stabilized by inter-CH2 domain sugar contacts. Zinc appears to counteract the sugar mediated constriction, suggesting that zinc could be an important control factor in IgG1/FcγR interactions. The results of binding studies performed in the presence of EDTA on FcγR expressing cells supports this hypothesis. When a mutated Fc fragment, in which histidines 310 and 435 have been substituted by lysines (Fc H/K), was compared with the wild-type Fc in crystallographic studies, we found that the mutations leave the interface unaltered but have a long-range effect on the CH2 interdomain separation. Moreover, these substitutions have a differential effect on the binding of IgG1 to Fcγ receptors and their functions. Interaction with the inhibitory FcγRIIB is strongly perturbed by the mutations and mutant IgG1 H/K only weakly engages this receptor. By contrast, higher affinity FcγR are mostly unaffected.

Zinc supplementation and TNF-α levels in vaccinated cardiac patients

OBJECTIVE

To investigate whether zinc supplementation could affect serum tumor necrosis factor-alpha (TNF-α) levels in congenital and acquired cardiac patients attending for an influenza vaccine.

METHODS

9-18 years old, voluntary children with cardiac disease were weighed, measured height and blood samples for hemoglobin level, zinc level, IgA and IgG titers of influenza A and B serotypes and TNF-α levels were obtained. The children were randomly assigned to 1 of 2 groups: ZV group received both zinc supplementation and influenza vaccine; V group received influenza vaccine. Serum TNF-α levels were measured at 28 days after the immunization.

RESULTS

Mean (±SD) serum zinc level was 100 (±20) μg/dL. Cases with congenital heart disease had lower serum zinc levels than acquired ones (93±17 μg/dL, 116±18 μg/dL; respectively, p<0.001). Median titers of serum TNF-α decreased after vaccination (78.9 pg/mL, 74.8 pg/mL; p<0.05) but this significant change occurred only in ZV group (77.1 pg/mL, 73.4 pg/mL; p=0.001). Vaccine associated adverse events were similar in ZV and V groups except malaise (0% in ZV and 23.8% in V group; p<0.05). Adverse events were similar in patients with congenital and acquired heart diseases. During the previous influenza season, 77.3% had more than two episodes of upper respiratory tract infection (URTI), however, after vaccination only 13.6% had more than two episode of URTI.

CONCLUSION

Zinc supplementation has a beneficial effect on malaise, one of the influenza vaccine associated adverse events, and decrease serum TNF-α levels.

Zinc deficiency: a frequent and underestimated complication after bariatric surgery

BACKGROUND

Although zinc deficiency is common after bariatric surgery, its incidence is underestimated. The objective was to monitor zinc and nutritional status before and 6, 12 and 24 months (M6, M12 and M24) after gastric bypass (Roux-en-Y gastric bypass), sleeve gastrectomy and biliopancreatic diversion with duodenal switch (DS) in patients receiving systematised nutritional care.

METHODS

Data for 324 morbidly obese patients (mean body mass index 46.2 ± 7.3 kg/m(2)) were reviewed retrospectively. The follow-up period was 6 months for 272 patients, 12 months for 175, and 24 months for 70. Anthropometric, dietary and serum albumin, prealbumin, zinc, iron and transferrin saturation measures were determined at each timepoint.

RESULTS

Nine percent of patients had zinc deficiency pre-operatively. Zinc deficiency was present in 42.5% of the population at M12 and then remained stable. Zinc deficiency was significantly more frequent after DS, with a prevalence of 91.7% at M12. Between M0 and M6, variation in plasma prealbumin, surgery type and zinc supplementation explained 27.2% of the variance in plasma zinc concentration. Surgery type explained 22.1% of this variance between M0 and M24. Mean supplemental zinc intake was low (22 mg/day). The percentage of patients taking zinc supplementation at M6, M12 and M24 was 8.9%, 20.6% and 29%, respectively.

CONCLUSIONS

Reduced protein intake, impaired zinc absorption and worsening compensatory mechanisms contribute to zinc deficiency. The mechanisms involved differ according to the type of surgery and time since surgery. Zinc supplementation is necessary early after bariatric surgery, but this requirement is often underestimated or is inadequate.

Essential role of vitamin C and zinc in child immunity and health

With the progressive elimination of dietary protein-energy deficits, deficiencies of micronutrients are emerging as the limiting factors in ensuring children's optimal health. Data from several countries in Asia and Latin America indicate that deficiencies of vitamin C and zinc continue to be at alarming levels. This article reviews the roles of vitamin C and zinc in supporting children's growth and development, with a particular focus on the complementary roles they play in supporting immune functions and combating infections. The contemporary relevance of vitamin C and zinc deficiency in the Asian and Latin American regions, both undergoing a rapid nutritional transition, are also discussed. Overall, there is increasing evidence that deficiency of vitamin C and zinc adversely affects the physical and mental growth of children and can impair their immune defences. Nutrition should be the main vehicle for providing these essential nutrients; however, supplementation can represent a valid support method, especially in developing regions.

The ubiquitous role of zinc in health and disease

OBJECTIVE

To review zinc physiology and pathophysiology and the importance of zinc toxicity and deficiency in veterinary patients.

DATA SOURCES

A review of human and veterinary medical literature.

HUMAN DATA SYNTHESIS

There is a significant amount of original research in humans and animals on the role of zinc in multiple organ systems. There is also significant data available on human patients with zinc abnormalities.

VETERINARY DATA SYNTHESIS

Zinc deficiency has been studied in dogs with genetic disease and dietary deficiency leading to dermatological disease and immune deficiency. Zinc toxicity has been described after ingestion of metallic foreign bodies containing zinc.

CONCLUSIONS

Historically, the role of zinc in health and disease has been studied through patients with toxicity or severe deficiency with obvious clinical signs. As the ubiquitous contribution of zinc to structure and function in biological systems was discovered, clinically significant but subtle deficiency states have been revealed. In human medicine, mild zinc deficiencies are currently thought to cause chronic metabolic derangement leading to or exacerbating immune deficiency, gastrointestinal problems, endocrine disorders, neurologic dysfunction, cancer, accelerated aging, degenerative disease, and more. Determining the causal relationships between mild zinc deficiency and concurrent disease is complicated by the lack of sensitive or specific tests for zinc deficiency. The prevalence of zinc deficiency and its contribution to disease in veterinary patients is not well known. Continued research is warranted to develop more sensitive and specific tests to assess zinc status, to determine which patients are at risk for deficiency, and to optimize supplementation in health and disease.

Functional significance of zinc-related signaling pathways in immune cells

Recent years have brought a paradigm shift for the role of the essential trace element zinc in immunity. Although its function as a structural component of many enzymes has been known for decades, current experimental evidence points to an additional function of the concentration of free or loosely bound zinc ions as an intracellular signal. The activity of virtually all immune cells is modulated by zinc in vitro and in vivo. In this review, we discuss the interactions of zinc with major signaling pathways that regulate immune cell activity, and the implications of zinc deficiency or supplementation on zinc signaling as the molecular basis for an effect of zinc on immune cell function.

Selected vitamins and trace elements support immune function by strengthening epithelial barriers and cellular and humoral immune responses

Adequate intakes of micronutrients are required for the immune system to function efficiently. Micronutrient deficiency suppresses immunity by affecting innate, T cell mediated and adaptive antibody responses, leading to dysregulation of the balanced host response. This situation increases susceptibility to infections, with increased morbidity and mortality. In turn, infections aggravate micronutrient deficiencies by reducing nutrient intake, increasing losses, and interfering with utilization by altering metabolic pathways. Insufficient intake of micronutrients occurs in people with eating disorders, in smokers (active and passive), in individuals with chronic alcohol abuse, in certain diseases, during pregnancy and lactation, and in the elderly. This paper summarises the roles of selected vitamins and trace elements in immune function. Micronutrients contribute to the body's natural defences on three levels by supporting physical barriers (skin/mucosa), cellular immunity and antibody production. Vitamins A, C, E and the trace element zinc assist in enhancing the skin barrier function. The vitamins A, B6, B12, C, D, E and folic acid and the trace elements iron, zinc, copper and selenium work in synergy to support the protective activities of the immune cells. Finally, all these micronutrients, with the exception of vitamin C and iron, are essential for antibody production. Overall, inadequate intake and status of these vitamins and trace elements may lead to suppressed immunity, which predisposes to infections and aggravates malnutrition. Therefore, supplementation with these selected micronutrients can support the body's natural defence system by enhancing all three levels of immunity.

Contribution of selected vitamins and trace elements to immune function

Adequate intakes of vitamins and trace elements are required for the immune system to function efficiently. Micronutrient deficiency suppresses immune functions by affecting the innate T-cell-mediated immune response and adaptive antibody response, and leads to dysregulation of the balanced host response. This increases the susceptibility to infections, with increased morbidity and mortality. In turn, infections aggravate micronutrient deficiencies by reducing nutrient intake, increasing losses, and interfering with utilization by altering metabolic pathways. Insufficient intake of micronutrients occurs in people with eating disorders, in smokers (both active and passive), in individuals with chronic alcohol abuse, in patients with certain diseases, during pregnancy and lactation, and in the elderly. With aging a variety of changes are observed in the immune system, which translate into less effective innate and adaptive immune responses and increased susceptibility to infections. Antioxidant vitamins and trace elements (vitamins C, E, selenium, copper, and zinc) counteract potential damage caused by reactive oxygen species to cellular tissues and modulate immune cell function through regulation of redox-sensitive transcription factors and affect production of cytokines and prostaglandins. Adequate intake of vitamins B(6), folate, B(12), C, E, and of selenium, zinc, copper, and iron supports a Th1 cytokine-mediated immune response with sufficient production of proinflammatory cytokines, which maintains an effective immune response and avoids a shift to an anti-inflammatory Th2 cell-mediated immune response and an increased risk of extracellular infections. Supplementation with these micronutrients reverses the Th2 cell-mediated immune response to a proinflammatory Th1 cytokine-regulated response with enhanced innate immunity. Vitamins A and D play important roles in both cell-mediated and humoral antibody response and support a Th2-mediated anti-inflammatory cytokine profile. Vitamin A deficiency impairs both innate immunity (mucosal epithelial regeneration) and adaptive immune response to infection resulting in an impaired ability to counteract extracellular pathogens. Vitamin D deficiency is correlated with a higher susceptibility to infections due to impaired localized innate immunity and defects in antigen-specific cellular immune response. Overall, inadequate intake and status of these vitamins and minerals may lead to suppressed immunity, which predisposes to infections and aggravates malnutrition.

Trace elemental analysis of normal, benign hypertrophic and cancerous tissues of the prostate gland using the particle-induced X-ray emission technique

Trace elemental analysis was carried out in the tissue samples of normal, benign hypertrophic and carcinoma prostate using the particle-induced X-ray emission technique. A proton beam of 3 MeV energy was used to excite the samples. The elements Cl, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Se, and Br were identified and their concentrations were estimated. It is observed that in benign tissues the concentrations of Cl, K, Zn, and Se are lower (P<0.05) and those of Cr, Fe, Ni, and Cu are higher (P<0.05 ) than in normal tissues. The concentrations of K, Ca, Zn, Se, and Br are lower (P<0.01) and those of Ti, Cr, Mn, Fe, Ni, and Cu are significantly higher (P<0.0005) in cancerous tissues than in normal tissues. Free radicals generated by elevated levels of Cr, Fe, Ni, and Cu possibly initiate and promote prostate cancer by oxidative DNA damage. The excess Cu levels in cancerous tissues support the fact that Cu promotes cancer through angiogenesis. The higher levels of Fe observed in cancerous tissues might be a consequence of tumor growth through angiogenesis. Significantly higher levels of Ni and Cr observed in carcinoma tissues support the well-established role of Ni and Cr as carcinogens. It is likely that the observed low levels of Zn and Se in cancerous tissues lead to the development of prostate cancer owing to a decrease in antioxidative defense capacity and impaired immune function of cells and also suggest that the inability to retain high levels of Zn and Se may possibly be an important factor in the development and progression of malignant prostate cells. In order to substantiate the observed elevated or deficient levels of trace elements in initiating, promoting, and inhibiting prostate cancer, several cellular and molecular studies are required.

Zinc status in infantile wheezing

The increase in prevalence of asthma is strongly dependent on environmental factors, including diet. Significant decreases in the intake of dietary zinc may be an important contributing factor to the increasing incidence of wheezing and asthma, but there have been no studies evaluating zinc levels in wheezy infants. Our objective was to investigate the zinc status of wheezy infants. Wheezy infants (n = 34) and healthy children (n = 14) were included in the study. Total IgE and eosinophil counts were obtained, and skin testing was done with a battery of 25 antigens with appropriate positive and negative controls. Levels of zinc were determined in hair, using a Polarized Zeeman Atomic Absorption Spectrophotometer (Hitachi Z-800). No significant difference was observed in peripheral blood eosinophil counts and total IgE levels among groups (P > 0.05). Hair zinc levels were significantly lower in wheezy infants (P < 0.001). In conclusion, hair zinc levels were lower in wheezy infants than in healthy controls, suggesting that zinc deficiency may influence the risk of wheezing in early childhood.

Importance of zinc in the elderly: the ZENITH study

The elderly are at nutritional risk as a result of multiple physiological, social, psychological, and economic factors. Physiological functions naturally decline with age, which may influence absorption and metabolism. Social and economic conditions can adversely affect dietary choices and eating patterns. However, at the same time, the nutrient needs of the elderly for certain nutrient (such as vitamins, minerals, proteins) is higher than for younger adults. This article reviews the importance of zinc (Zn) in elderly people, particularly for behavioural and mental function, micronutrient status, immune and antioxidant system, and bone metabolism.

Zinc status and age-related changes in peripheral blood leukocyte subpopulations in healthy men and women aged 55-70 y: the ZENITH study

OBJECTIVE

To determine zinc status and age-related changes in the immune function of healthy late-middle-aged men and women (aged 55-70 y).

DESIGN

Observational study.

SETTING

Population of Northern Ireland.

SUBJECTS

Apparently healthy, free-living individuals (45 men, 48 women) aged 55-70 y.

INTERVENTION

Zinc status markers were analysed by flame atomic absorption spectrometry and commercially available kits. Immune function was assessed by flow cytometry.

RESULTS

Serum and erythrocyte zinc concentrations were 13.0 (s.d. 1.40) micromol/l and 222 (s.d. 48.2) micromol/l, respectively. Serum alkaline phosphatase (ALP) concentrations were 76.8 (s.d. 16.1) U/l; women showed significantly higher concentrations of ALP (P = 0.011). Women demonstrated (1) a significant inverse correlation in naive T lymphocytes, specifically naive T-helper lymphocytes (% expression, r = -0.364, P = 0.007 and absolute count, r = -0.275, P = 0.036) with age and (2) a significant positive correlation between late activation of T lymphocytes (% expression, r = 0.299, P = 0.019 and absolute count, r = 0.260, P = 0.039) with advancing age. Men demonstrated a significant positive correlation in the % expression of (CD3-/CD16+/CD56+) natural killer (NK) cells with age (r = 0.316, P = 0.017).

CONCLUSIONS

Between the ages of 55 and 70 y, healthy individuals experience significant alterations in immune function; however, such changes appear largely sex specific. Given the reported importance of adequate zinc status in maintaining optimal immune function, further studies are required to explore the effect of enhanced zinc status on emerging immune deficiencies in cell-mediated immunity in healthy 55-70 y olds.

Immune-enhancing role of vitamin C and zinc and effect on clinical conditions

Vitamin C concentrations in the plasma and leukocytes rapidly decline during infections and stress. Supplementation of vitamin C was found to improve components of the human immune system such as antimicrobial and natural killer cell activities, lymphocyte proliferation, chemotaxis, and delayed-type hypersensitivity. Vitamin C contributes to maintaining the redox integrity of cells and thereby protects them against reactive oxygen species generated during the respiratory burst and in the inflammatory response. Likewise, zinc undernutrition or deficiency was shown to impair cellular mediators of innate immunity such as phagocytosis, natural killer cell activity, and the generation of oxidative burst. Therefore, both nutrients play important roles in immune function and the modulation of host resistance to infectious agents, reducing the risk, severity, and duration of infectious diseases. This is of special importance in populations in which insufficient intake of these nutrients is prevalent. In the developing world, this is the case in low- and middle-income countries, but also in subpopulations in industrialized countries, e.g. in the elderly. A large number of randomized controlled intervention trials with intakes of up to 1 g of vitamin C and up to 30 mg of zinc are available. These trials document that adequate intakes of vitamin C and zinc ameliorate symptoms and shorten the duration of respiratory tract infections including the common cold. Furthermore, vitamin C and zinc reduce the incidence and improve the outcome of pneumonia, malaria, and diarrhea infections, especially in children in developing countries.

Role of reactive oxygen species in zinc deficiency-induced hepatic stellate cell activation

We previously reported that zinc deficiency caused a reduction in intracellular glutathione at 8 h after the addition of zinc chelator, diethylenetriamine pentaacetic acid (DTPA), compared with control levels in rat hepatic stellate cells. In this study, we investigated the role of reactive oxygen species and glutathione on the mechanism of zinc deficiency-induced hepatic stellate cell activation, via assessing collagen synthesis. Isolated hepatic stellate cells were incubated with or without DTPA. Type I collagen expression in hepatic stellate cells was detected by immunohistochemistry, and then quantification of the intensity of type I collagen expression was analyzed using a computer with NIH image. Intracellular glutathione was measured using HPLC. H(2)O(2) release from hepatic stellate cells into the overlying medium was assayed using a fluorimetric method. H(2)O(2) release by DTPA-treated hepatic stellate cells significantly increased from 4 h, but returned to control levels after zinc supplementation. When catalase was added to the culture at 6 h after the addition of DTPA, the staining for type I collagen was as weak as at control levels. Diphenyliodonium chloride, the inhibitor of NADPH oxidase, produced a marked reduction in zinc deficiency-induced H(2)O(2) release. The results of this study show that the depletion of intracellular glutathione levels triggers a progression of collagen synthesis in zinc deficient-hepatic stellate cells and this depletion may be induced by the stimulation of cellular production of H(2)O(2).

Involvement of intracellular glutathione in zinc deficiency-induced activation of hepatic stellate cells

Hepatic stellate cells (HSC) play an important role in the development of liver cirrhosis. They are a major source of extracellular matrix and during fibrogenesis undergo an activation process characterized by increased proliferation and collagen synthesis. In this study, we investigated the anti-fibrogenic effect of zinc supplementation on zinc deficiency induced HSC activation. Isolated HSC were incubated with or without zinc chelator, diethylenetriamine penta-acetic acid (DTPA). Type I collagen expression in HSC was detected by immunohistochemistry. The involvement of glutathione (GSH) homeostasis in the anti-fibrogenic action of zinc was also investigated, as GSH is implicated in many cellular events, such as regulation of cell proliferation, remodeling of extracellular matrix and oxidative stress. Intracellular GSH was measured by HPLC. Enhanced type I collagen expression, apoptosis and cell cycle arrest were found in HSC when DTPA was added, but they were inhibited with supplementation with zinc. Zinc deficiency caused a reduction in intracellular GSH 8 h after the addition of DTPA compared with control levels. The results of this study show that in HSC, the chelation of zinc triggers a progression of collagen synthesis and this involves the depletion of intracellular GSH levels after the addition of DTPA.

Zinc-altered immune function

Zinc is known to be essential for all highly proliferating cells in the human body, especially the immune system. A variety of in vivo and in vitro effects of zinc on immune cells mainly depend on the zinc concentration. All kinds of immune cells show decreased function after zinc depletion. In monocytes, all functions are impaired, whereas in natural killer cells, cytotoxicity is decreased, and in neutrophil granulocytes, phagocytosis is reduced. The normal functions of T cells are impaired, but autoreactivity and alloreactivity are increased. B cells undergo apoptosis. Impaired immune functions due to zinc deficiency are shown to be reversed by an adequate zinc supplementation, which must be adapted to the actual requirements of the patient. High dosages of zinc evoke negative effects on immune cells and show alterations that are similar to those observed with zinc deficiency. Furthermore, when peripheral blood mononuclear cells are incubated with zinc in vitro, the release of cytokines such as interleukins (IL)-1 and -6, tumor necrosis factor-alpha, soluble IL-2R and interferon-gamma is induced. In a concentration of 100 micro mol/L, zinc suppresses natural killer cell killing and T-cell functions whereas monocytes are activated directly, and in a concentration of 500 micro mol/L, zinc evokes a direct chemotactic activation of neutrophil granulocytes. All of these effects are discussed in this short overview.