Effect of zinc supplementation on antioxidant activity in young wrestlers

Effects of Perioperative Zinc Supplementation on Copper Circulating Levels and Expression of Metallothionein and Copper Antioxidant Chaperone-1 in Leukocytes in Patients Undergoing CABG Surgery

The use of zinc supplement may have a negative effect on copper status. The objective of this study was to evaluate the effect of zinc and vitamin E supplementation on copper and zinc biomarkers in patients undergoing coronary artery bypass graft (CABG) surgery. The study was an add-on project to a previously published randomized controlled trial (NCT05402826) on patients undergoing CABG surgery. Patients in the zinc-vitamin E group (n = 40) received oral zinc (120 mg) and vitamin E (1200 international units) 1 day before surgery, followed by 30 mg of zinc and 200 units of vitamin E per day until 21 days after surgery, while those in the control group (n = 38) received placebo. Plasma levels of copper, ceruloplasmin, superoxide dismutase (SOD) activity, as well as leukocyte gene expression of metallothionein 2A (MT2A) and antioxidant protein 1 (ATOX1), were determined 3 and 21 days after surgery. The plasma copper level in the zinc-vitamin E group was significantly lower than the placebo group on the 3rd postoperative day, but no significant between-group differences were observed on day 21. Plasma ceruloplasmin concentration and SOD activity were not different. Relative mRNA expression of leukocyte MT2A was increased at both times (days 3 and 21 in the zinc-vitamin E group compared to placebo, but ATOX1 expression was not affected. Although the plasma copper level was transiently decreased early after surgery in the zinc-vitamin E group, considering the lack of change in other copper biomarkers, it seems that the use of zinc supplements at the dose used in the present study does not have a significant negative effect on the role of intracellular copper.

Antioxidants and Sports Performance

The role of reactive oxygen species and antioxidant response in training adaptations and sports performance has been a large issue investigated in the last few years. The present review aims to analyze the role of reactive oxygen species and antioxidant response in sports performance. For this aim, the production of reactive oxygen species in physical activities, the effect of reactive oxygen species on sports performance, the relationship between reactive oxygen species and training adaptations, inflammation, and the microbiota, the effect of antioxidants on recovery and sports performance, and strategies to use antioxidants supplementations will be discussed. Finally, practical applications derived from this information are discussed. The reactive oxygen species (ROS) production during physical activity greatly influences sports performance. This review concludes that ROS play a critical role in the processes of training adaptation induced by resistance training through a reduction in inflammatory mediators and oxidative stress, as well as appropriate molecular signaling. Additionally, it has been established that micronutrients play an important role in counteracting free radicals, such as reactive oxygen species, which cause oxidative stress, and the effects of antioxidants on recovery, sports performance, and strategies for using antioxidant supplements, such as vitamin C, vitamin E, resveratrol, coenzyme Q10, selenium, and curcumin to enhance physical and mental well-being.

Preparation and characterization of garlic polysaccharide-Zn (II) complexes and their bioactivities as a zinc supplement in Zn-deficient mice

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Garlic polysaccharide-Zn (II) complexes were prepared.

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The structural characterization confirmed the formation of complexes.

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The complexes could significantly improve the health of Zn-deficient mice.

This study explored the potential of garlic polysaccharides (GPs) as a carrier for synthesizing GP-Zn (II) complexes to supplement Zn. According to the response surface analysis, the optimal preparation conditions were: mass ratio of GPs to Zn²⁺ 1:0.21, temperature 53 °C, pH 5.9 and time 148.75 min, with the maximum chelation rate of 90.11%. The chelation of GPs and Zn²⁺ involved O—H/C—O/O—C—O groups, increased crystallinity and altered absorption peaks of circular dichroism spectra, with a higher thermal stability, particle size and negative zeta potential. Compared with inorganic zinc salts, supplementation of GP-Zn (II) complexes showed enhance zinc supplementation effects in Zn-deficient mice model: increased body weight, organ index and Zn (II) levels in serum and liver, enhanced Superoxidedismutase (SOD) activity and alkaline phosphatase activity, decreased NO content and Malondialdehyde (MDA) content and improved colon and testicular morphology. Therefore, GP-Zn (II) complex can be used as a potential zinc supplement for Zn-deficient individuals.

Dopaminergic Neuronal Death in Substantia Nigra Associates with Serum Levels of Total Bilirubin, Selenium, and Zinc: Evidences from 6-Hydroxydopamine Animal Model of Parkinson's Disease

Mild to moderate dopaminergic (DA) neuronal death in substantia nigra pars compacta (SNc) as the main pathological hallmark of Parkinson's disease (PD) is usually silent and does not produce marked clinical symptoms. In this study, we investigated the association between SNc DA neuronal loss and serum levels of total bilirubin (TB), selenium (Se), and zinc (Zn) in 6-hydroxydopamine (6-OHDA) animal model of PD. The neurotoxin of 6-OHDA was injected into the medial forebrain bundle of right hemisphere by stereotaxic surgery. Two conventional behavioral tests were carried out in several steps after the toxin to confirm the model reproduction and quantify severity and progress of 6-OHDA-induced PD. Blood samples were collected within 1 week before the toxin and in the second, fifth, and eighth weeks thereafter. Immunohistochemistry (IHC) assessments were performed on the rat's brain to determine the severity of DA neuronal loss in SNc. The severity of behavioral symptoms and TB levels were progressively increased in 6-OHDA-treated rats. On the other hand, Se and Zn levels in them were lower than control. These changes were observed in rats with severe or mild behavioral symptoms. Also, IHC revealed that changes in TB, Se, and Zn associate with SNc DA neuronal loss but do not correlate with its severity. Significant changes in serum levels of TB, Se, and Zn in the mild SNc DA neuronal loss suggest them as valuable parameters for establishment of a serum profile for early detection of PD.

Effects of ergo-nutritional strategies on recovery in combat sports disciplines

Introduction

In order to improve the recovery process in combat sports disciplines, ergo-nutritional strategies could be an effective option in training and competition. Some of these ergo-nutritional aids could improve performance but literature references are scarce, with controversial results regarding actual recovery effects. This systematic review aimed to examine which ergo-nutritional methods are most effective for assisting in the recovery process in combat sports, and to determine the appropriate training stimuli. This systematic review was carried out following the Preferred Reporting Items for Systematic Review (PRISMA) guidelines. A computerized search was performed in PubMed, Web of Science, the Cochrane Collaboration Database, Evidence Database, Evidence Based Medicine Search review, National Guidelines, EM-BASE, Scopus and Google Scholar system (from 1995 to April 30, 2021). The PICOS model was used to define inclusion and exclusion criteria. Out of 123 studies initially found, 18 met the eligibility criteria and were included in the review. Data from 367 athletes from different disciplines were examined. The evidence was grouped in 4 areas: oxidative stress, muscle and energy recovery, muscle repair, and metabolic acidosis. Evidence showed that vitamins, minerals, and some natural ergo-nutritional products are effective as antioxidants. Carbohydrates and protein determine the recovery effect. Sodium bicarbonate has a role as primary acidosis metabolic delayer. Accordingly, ergo-nutritional aids can help in the recovery process. Considering the effects outlined in the literature, more studies are needed to provide firm evidence.

Aberrance of Zinc Metalloenzymes-Induced Human Diseases and Its Potential Mechanisms

Zinc, an essential micronutrient in the human body, is a component in over 300 enzymes and participates in regulating enzymatic activity. Zinc metalloenzymes play a crucial role in physiological processes including antioxidant, anti-inflammatory, and immune responses, as well as apoptosis. Aberrant enzyme activity can lead to various human diseases. In this review, we summarize zinc homeostasis, the roles of zinc in zinc metalloenzymes, the physiological processes of zinc metalloenzymes, and aberrant zinc metalloenzymes in human diseases. In addition, potential mechanisms of action are also discussed. This comprehensive understanding of the mechanisms of action of the regulatory functions of zinc in enzyme activity could inform novel zinc-micronutrient-supply strategies for the treatment of diseases.

Influence of Zinc on the Acute Changes in Erythropoietin and Proinflammatory Cytokines with Hypoxia

Baranauskas, Marissa N., Joseph Powell, Alyce D. Fly, Bruce J. Martin, Timothy D. Mickleborough, Hunter L. Paris, and Robert F. Chapman. Influence of zinc on the acute changes in erythropoietin and proinflammatory cytokines with hypoxia. High Alt Med Biol. 22: 148-156, 2021. Background: Considerable, unexplained, interindividual variability characterizes the erythropoietin (EPO) response to hypoxia, which can impact hematological acclimatization for individuals sojourning to altitude. Zinc supplementation has the potential to alter EPO by attenuating increases in inflammation and oxidative stress. Yet, the application of such an intervention has not been evaluated in humans. In this proof-of-concept study, we aimed to evaluate the EPO and inflammatory responses to acute hypoxia in human participants following chronic zinc supplementation. Methods: Nine physically active participants (men n = 5, women n = 4, age 28 ± 4 years, height 176 ± 11 cm, mass 77 ± 21 kg) were exposed to 12 hours of normobaric hypoxia simulating an altitude of 3,000 m (F_iO₂ = 0.14) before and after 8 weeks of supplementation with 40 mg/day of elemental zinc from picolinate. Blood samples for subsequent analysis of serum zinc, EPO, superoxide dismutase (extracellular superoxide dismutase [EC-SOD]), C-reactive protein (CRP), and proinflammatory cytokines were obtained pre- and postsupplementation and exposure to hypoxia. Results: After zinc supplementation, EPO increased by 64.9 ± 36.0% (mean ± standard deviation) following 12 hours of hypoxia, but this response was not different from presupplementation (70.8 ± 46.1%). Considerable interindividual (range: -1% to +208%) variability was apparent in the acute EPO response. While most markers of inflammation did not change with hypoxia, interleukin-6 concentrations increased from 1.17 ± 0.05 to 1.97 ± 0.32 pg/ml during the final 6 hours. The acute EPO response at 12 hours was not related to changes in serum zinc, EC-SOD, CRP, or proinflammatory cytokines. Conclusions: Zinc supplementation does not influence the acute EPO or inflammatory response with short-term exposure to moderate levels of normobaric hypoxia (3,000 m) in apparently healthy young adults.

Anacardic Acid Complexes as Possible Agents Against Alzheimer's Disease Through Their Antioxidant, In vitro, and In silico Anticholinesterase and Ansiolic Actions

The frequency of Alzheimer's disease (AD) is growing rapidly with longer life expectancy and the consequent increase of people with a high risk of neurodegenerative diseases. Anacardic acid (AA) has several pharmacological actions, such as antioxidants, anticholinesterase, and anti-inflammatory, which are related to the protection against aging disorders. Also, the metals copper and zinc are co-factors of antioxidant enzymes that can be associated with AA to improve brain-protective action. This study aimed to evaluate the potential of AA metal complexes using copper and zinc chelators to produce potential agents against Alzheimer's disease. For this purpose, Cu and Zn were linked to AA in the ratio of 1:1 in a basic medium. The complexes' formation was confirmed by ultraviolet and visible spectroscopy. The toxicity was evaluated in the zebrafish model, and other information related to AD was obtained using the zebrafish model of anxiety. AA-Zn and AA-Cu complexes showed better antioxidant action than free AA. In the anti-AChE activity, AA was like the AA-Cu complex. In models using adult zebrafish, no toxicity for AA complexes was found, and in the locomotor model, AA-Cu demonstrated possible anxiolytic action. In in silico experiments comparing AA and AA-Cu complex, the coupling energy with the enzyme was lower for the AA-Cu complex, showing better interaction, and also the distances of the active site amino acids with this complex were lower, similar to galantamine, the standard anti-AChE inhibitor. Thus, AA-Cu showed interesting results for more detailed study in experiments related to Alzheimer's disease.

Green synthesis of CuO- and Cu2O-NPs in assistance with high-gravity: The flowering of nanobiotechnology

This study, for the first time, reports the synthesis of CuO- and Cu2O nanoparticles (NPs) using the Salvia hispanica extract by a high-gravity technique. The original green synthesis procedure led to the formation of nanoparticles with promising catalytic and biological properties. The synthesized nanoparticles were fully characterized and their catalytic activity was evaluated through a typical Azide-Alkyne Cycloaddition (AAC) reaction. The potential antibacterial activity against gram positive (S. aureus) and gram negative (E. coli) bacteria were investigated. It was shown that the antibacterial properties were independent of the NP morphology as well as of the texture of the synthesis media. As a result, the presently synthesized nanoparticles showed very good photocatalytic and catalytic activities in comparison with the literature. From a biological perspective, they showed lower cytotoxicity in comparison with the literature, and also showed higher antioxidant and antibacterial activities. Thus, these present green CuO and Cu2O nanoparticles deserve further attention to improve numerous medical applications.

The Effect of Exercise and Psychological Stress on Anti- and Proinflammatory Cytokines

BACKGROUND/AIMS

Research evidence regarding immune system responses and adaptations to psychological or physical stresses is controversial. This study aimed to investigate the effect of 8-week psychological stress and exercise activity (chronic adaptation) and the acute response of possibly adapted rats to psychological stress and exercise considering IFN-γ, IL-4, and IL-4/IFN-γ.

METHODS

Thirty-two rats were divided into 4 groups of 8 animals including control, exercise, psychological stress, and combination of exercise with psychological stress. IL-4 and IFN-γ cytokines were measured pre-experiment (preEX), immediately postexercise (IpostEX), and 72-h postexperiment protocol (72hpostEX).

RESULTS

There were no significant differences between the study groups regarding IFN-γ, IL-4, and IL-4/IFN-γ in preEX (p > 0.05), IpostEX (p > 0.05), and 72hpostEX (p > 0.05). However, IL-4 increased significantly in IpostEX compared with preEX in exercise (p = 0.012) and combination of exercise with psychological stress (p = 0.03) groups.

CONCLUSIONS

Exercise and combination of exercise and psychological stress induce similar acute response to IL-4 in chronic trained and stressed rats. Also, exercise may induce an acute synergistic effect with psychological stress on IL-4.

No Relation Between Zinc Status and Inflammatory Biomarkers in Adolescent Judokas

This study aimed to assess the relation between zinc status and inflammation biomarkers in adolescent judokas. This cross-sectional study included 52 male adolescents, aged between 14 and 19 years, who were subdivided into two groups: judoka group (n = 25) and control group (n = 27). Zinc intake was monitored using 3-day food records and the NutWin software version 1.5. The plasma and erythrocyte zinc concentrations were determined by flame atomic absorption spectrophotometry. Analysis of cytokines (IL-1β, IL-6, and TNF-α) was performed. The mean values of zinc concentration in the diet were found to be higher than those recommended (11.0±3.9 mg/day and 20.3±11.9 mg/day for control group and judokas, respectively) although there was no significant difference between the groups. The mean plasma concentrations of zinc were below the reference range (71.4±16.0 μg/dL and 71.9±13.8 μg/dL for control group and judokas, respectively), without a significant difference between the groups. The mean concentrations of zinc erythrocyte were within the reference range (41.2±8.6 μg/gHb and 42.6±11.3 μg/gHb for control group and judokas, respectively), without a significant difference between the groups. There was no significant difference in the inflammatory biomarkers between the judokas and controls. There was not a significant correlation between biochemical parameters of zinc and inflammation biomarkers in adolescent judokas. Regarding the data found in the study, it can be concluded that the athletes evaluated have low plasma zinc concentrations, normal erythrocyte values, and high dietary intake of zinc. Moreover, the study don't show a relationship between zinc parameters and inflammatory markers evaluated.

Serum concentration of cobalt, molybdenum and zinc in aerobic, anaerobic and aerobic-anaerobic sportsmen

BACKGROUND

The aim of the present study was to determine changes in the serum concentrations of trace elements Cobalt (Co), Molybdenum (Mo) and Zinc (Zn) among high-level sportsmen.

METHODS

Eighty professional athletes of different metabolic modalities (aerobic, anaerobic and aerobic-anaerobic), were recruited before the beginning of their training seasons. Thirty-one sedentary participants of the same geographic area constituted the control group. Co, Mo and Zn analysis was performed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS).

RESULTS

Serum concentration of Mo (p < 0.001) was higher among sportsmen compared to the control group values. Separated by modalities, the concentrations of Co in the aerobic-anaerobic athletes were lower (p < 0.01) than in the control group as well as than in the other athletes. The highest Mo concentration was found in anaerobic sportsmen (p < 0.001), followed by aerobic-anaerobic (p < 0.001) being both statistically higher in comparison with the control group. In relation to Zn, it was observed that aerobic-anaerobic (p < 0.001) and anaerobic (p < 0.001) sportsmen showed higher concentrations than the control participants. However, aerobic sportsmen showed lower concentrations (p < 0.01) than controls.

CONCLUSION

This data manifest that long-term, daily physical training may induce variations in serum concentrations of several essential elements among sportsmen in comparison to untrained men and that these changes seems to be related to the sports modality practiced.

Association Between Serum Zinc Levels and the Risk of Parkinson's Disease: a Meta-Analysis

Recent studies have found that the serum zinc levels were associated with the risk of Parkinson's disease (PD), but the results were inconsistent. Thus, we conducted a meta-analysis to summarize the evidence from observational studies between them. Pertinent studies were identified by a search in PubMed, Embase, and Web of science up to July, 10, 2016. Standardized mean difference (SMD) and 95% confidence intervals (CI) with random-effect model was used to combine the results. Subgroup analysis and meta-regression were also conducted. Publication bias was estimated using Begg's regression asymmetry test. A total of 11 articles involving 822 PD patients and 777 healthy controls were included in the meta-analysis. Our meta-analysis results revealed that the serum zinc levels in PD patients were significantly lower than those in health controls (SMD = -0.779, 95%CI = [-1.323, -0.234], P < 0.001). The association was also significant oriental studies (SMD = -1.601, 95%CI = [-2.398, -0.805], P < 0.001). No publication bias was found. The current study indicated that serum zinc levels in PD patients were significantly lower than those in healthy controls.

Effect of a four-week exercise program on the secretion of IFN-γ, TNF-α, IL-2 and IL-6 cytokines in elite Taekwondo athletes

The aim of the present study was to examine how a 4-week exercise program affects the serum levels of certain cytokines in Taekwondo athletes. The study involved 10 elite male Taekwondo athletes (mean age, 20.67±0.24 years; mean weight, 65.45±1.69 kg) who were studying at the Physical Education and Sports High School of Selçuk University (Konya, Turkey) in June 2014. The subjects were involved in a Taekwondo exercise program on every weekday for 4 weeks. The subjects were also engaged in an exercise to exhaustion session twice; once before starting the 4-week exercise program and once upon completion of the program. Blood samples were collected from the subjects in four rounds: During rest, upon fatigue, and before and after the 4-week exercise program. These samples were analyzed to establish the serum levels of interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), interleukin (IL)-2 and IL-6 using enzyme-linked immunosorbent assay test kits. Pre- and post-exercise program, the IFN-γ and TNF-α levels did not show any significant difference. When compared with the pre-exercise levels, serum IL-2 levels of the subjects were found to be elevated after the 4-week exercise program. The highest serum IL-6 values were established after the subjects were exercised to fatigue before the exercise program was initiated (P<0.05). The 4-week exercise program resulted in a decrease in IL-6 levels (P<0.05). The findings of the study indicate that a 4-week exercise program did not result in significant changes in IFN-γ and TNF-α levels, but led to an increase in IL-2 levels. The notable finding of the present study is that a 4-week exercise program reduces cellular immune functions and, thus, the levels of IL-6, which negatively influences performance.

The protective effects of zinc in lead-induced testicular and epididymal toxicity in Wistar rats

The aim of this study was to investigate the beneficial effects of zinc (Zn) in preventing lead (Pb)-induced reproductive toxicity in Wistar rats. The rats were divided into four groups, namely, control group, Pb group, Zn group, and Pb + Zn group. Animals were exposed to Pb (819 mg of Pb/L) or Zn (71 mg of Zn/L) or both through drinking water for 65 days. Rats exposed to Pb showed decreased weights of testes and accessory sex organs. Significant decrease in the testicular daily sperm production, epididymal sperm count, motility, viability, and number of hypoosmotic tail coiled sperm was observed in Pb-exposed rats. Testicular 3β- and 17β-hydroxysteroid dehydrogenase activity levels and circulatory testosterone levels were also decreased significantly in Pb-exposed rats. A significant increase in the lipid peroxidation products with a significant decrease in the activities of catalase and superoxide dismutase were observed in the testes and epididymis of Pb-exposed rats. Moreover, the testicular architecture showed lumens devoid of sperm in Pb-exposed rats. Supplementation of Zn mitigated Pb-induced oxidative stress and restored the spermatogenesis and steroidogenesis in Pb-exposed rats. In conclusion, cotreatment of Zn is effective for recovering suppressed spermatogenesis, steroidogenesis, elevated oxidative status, and histological damage in the testis of rats treated with Pb.

Anti-inflammatory and antioxidant properties of unripe papaya extract in an excision wound model

CONTEXT

Carica papaya L. (Caricaceae) fruit was shown to exhibit wound healing properties.

OBJECTIVES

We investigated anti-inflammatory and antioxidant potential of papaya fruit phosphate-buffered saline extract (PE) during wound healing and enhancement of the potentials due to trace ions addition.

MATERIALS AND METHODS

Rat excision wounds were topically treated twice/day with 20 µL of PE (5 mg extract/mL), 0.5 µg Se(2+) added PE (PES), or 100 µM Zn(2+) added PE (PEZ). Control groups were treated with deionized water (negative) and deproteinized calf blood extract ointment (Solcoseryl®, positive). Lipid peroxidation (LPX), antioxidant, proinflammatory, and arginine metabolic enzymes were estimated in the wound excised on days 4 and 10 post wounding.

RESULTS

PE (5 mg/mL; 9.80 ± 0.33 d) and PES (PE + 0.5 µg Se(2+); 8.90 ± 0.23 d) significantly (p < 0.05) reduced the average time for complete wound closure compared with the negative (13.00 ± 0.37 d) and positive (9.80 ± 0.33 d) controls, respectively. Biochemical evaluations of LPX product (malondialdehyde), antioxidant (catalase, superoxide dismutase (SOD), and glutathione peroxidase (GPx)), and pro-inflammatory (cyclooxygenase-2 and myeloperoxidase (MPO)) enzyme activities and metabolites (nitrite and urea), on days 4 and 10 post wounding, confirmed the anti-inflammatory and antioxidant properties of PE and PES in this study.

DISCUSSION AND CONCLUSION

Treatment of excision wounds with papaya extract, especially with the addition of selenium for 10 d, reduced inflammation associated oxidative damage apparently via cyclooxygenase specific inhibition, arginine metabolism, and up-regulation of antioxidant enzymes.

Influence of training frequency on serum concentrations of some essential trace elements and electrolytes in male swimmers

Elemental fluctuations during physical performances have been a point of interest. This study was designed to investigate the effect of swimming frequency on serum concentrations of some trace elements (chromium, iron, copper, zinc, selenium) and electrolytes (sodium, magnesium, potassium, calcium). Three groups of different-level male swimmers were included in the study, as elite swimmers (n = 14), amateur swimmers (n = 11), and sedentary individuals (n = 10). Elite and amateur swimmer groups followed a 3-week training program. At the end of the period, all volunteers were subjected to a controlled swimming test, and blood samples were collected at the beginning of (pre-test), immediately after (post-test), and 1 h after this activity. Element concentrations were determined by inductively coupled plasma mass spectrometry using a dilute and shoot procedure. Apart from the swimming test applied, pre-test calcium and potassium levels were higher in elite swimmers compared to amateurs and controls. The difference in pre-test levels of these elements can be associated with adaptive mechanisms emerged by the frequent training. Regarding the test applied, changes in magnesium, calcium, copper, zinc, and selenium levels exhibited a common pattern in all study groups, with higher post-test serum concentrations. Another point of note was a drop of copper, zinc, and selenium levels at 1 h after the test in elite swimmers. The decrease in serum zinc was also observed in the other groups. Results highlight the value of regular control of elemental status to provide insight into transient effects and deficiencies.

Is the Mediterranean diet adequate to satisfy zinc requirements during adolescence?

OBJECTIVE

To evaluate Zn utilization and status among a sample of Spanish boys consuming a diet based on Mediterranean patterns.

DESIGN

Dietary Zn balance was assessed by means of Zn intake in food and Zn output in faeces and urine as measured by flame atomic absorption spectrophotometry. In addition, biomarkers of Zn status were analysed.

SETTING

Province of Granada, Spain.

SUBJECTS

Twenty healthy male adolescents aged 11-14 years, selected based on medical questionnaire, physical examination and nutritional survey of food habits and lifestyle.

RESULTS

Mean Zn intake was 11·36 (se 0·31) mg/d, 76% of the recommended value for Spanish adolescents. Zn absorption (2·53 (se 0·55) mg/d) was close to the value of 3·0 mg/d required for the growth spurt. Zn status biomarkers and growth parameters were within the normal values for this age group.

CONCLUSIONS

Although a diet based on Mediterranean patterns is associated with factors which can affect Zn absorption, such as high consumption of phytate, its consumption in adequate amounts allows Zn status to be maintained during adolescence. Due to the importance of Zn in preventing growth and behavioural disorders among adolescents, long-term intervention trials to investigate the suitability of the Mediterranean diet with respect to Zn requirements at this time of life are needed.

Plasma zinc, copper, and serum thyroid hormones and insulin levels after zinc supplementation followed by placebo in competitive athletes

Intense physical activity is associated with biological adaptations involving hormones and trace elements. Zinc supplementation may affect plasma copper concentration, thyroid-stimulating hormone (TSH), thyroid hormones, insulin, and glucose homeostasis, but data in athletes are scarce. The aim of this study was to evaluate in competitive athletes (cyclists, n = 7, 32 ± 8 years) the effect of zinc supplementation (22 mg/day as zinc gluconate) during 30 days, and discontinuation using placebo (maltodextrin) during the following 30 days, on plasma zinc and copper concentrations, serum thyroid hormones, insulin and glucose levels, and HOMA2-IR. Compared to baseline, plasma zinc and Zn:Cu plasma ratio increased, but plasma copper decreased after zinc supplementation (day 30) and discontinuation (day 60) (p < 0.05). Zn supplementation and discontinuation had no effect on TSH, T3, and T4. Fasting serum insulin and HOMA2-IR increased (27% and 47%, respectively) on day 60 compared to baseline (p = 0.03), suggesting a delayed effect of zinc supplementation. Moreover, plasma zinc was positively associated with serum insulin (r = 0.87, p = 0.009) and HOMA2-IR (r = 0.81, p = 0.03) after zinc supplementation (day 30), indicating that supplemental zinc may impair glucose utilization in cyclists.