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Hall AG, King JC. The Molecular Basis for Zinc Bioavailability. Int J Mol Sci 2023; 24:ijms24076561. [PMID: 37047530 PMCID: PMC10095312 DOI: 10.3390/ijms24076561] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 03/25/2023] [Accepted: 03/30/2023] [Indexed: 04/03/2023] Open
Abstract
Zinc is an essential micronutrient, and its deficiency is perhaps the most prevalent and least understood worldwide. Recent advances have expanded the understanding of zinc’s unique chemistry and molecular roles in a vast array of critical functions. However, beyond the concept of zinc absorption, few studies have explored the molecular basis of zinc bioavailability that determines the proportion of dietary zinc utilized in zinc-dependent processes in the body. The purpose of this review is to merge the concepts of zinc molecular biology and bioavailability with a focus on the molecular determinants of zinc luminal availability, absorption, transport, and utilization.
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Zinc Fortification: Current Trends and Strategies. Nutrients 2022; 14:nu14193895. [PMID: 36235548 PMCID: PMC9572300 DOI: 10.3390/nu14193895] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Revised: 09/13/2022] [Accepted: 09/16/2022] [Indexed: 11/17/2022] Open
Abstract
Zinc, through its structural and cofactor roles, affects a broad range of critical physiological functions, including growth, metabolism, immune and neurological functions. Zinc deficiency is widespread among populations around the world, and it may, therefore, underlie much of the global burden of malnutrition. Current zinc fortification strategies include biofortification and fortification with zinc salts with a primary focus on staple foods, such as wheat or rice and their products. However, zinc fortification presents unique challenges. Due to the influences of phytate and protein on zinc absorption, successful zinc fortification strategies should consider the impact on zinc bioavailability in the whole diet. When zinc is absorbed with food, shifts in plasma zinc concentrations are minor. However, co-absorbing zinc with food may preferentially direct zinc to cellular compartments where zinc-dependent metabolic processes primarily occur. Although the current lack of sensitive biomarkers of zinc nutritional status reduces the capacity to assess the impact of fortifying foods with zinc, new approaches for assessing zinc utilization are increasing. In this article, we review the tools available for assessing bioavailable zinc, approaches for evaluating the zinc nutritional status of populations consuming zinc fortified foods, and recent trends in fortification strategies to increase zinc absorption.
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Canovai A, Amato R, Melecchi A, Dal Monte M, Rusciano D, Bagnoli P, Cammalleri M. Preventive Efficacy of an Antioxidant Compound on Blood Retinal Barrier Breakdown and Visual Dysfunction in Streptozotocin-Induced Diabetic Rats. Front Pharmacol 2022; 12:811818. [PMID: 35046830 PMCID: PMC8762314 DOI: 10.3389/fphar.2021.811818] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 12/06/2021] [Indexed: 12/13/2022] Open
Abstract
In diabetic retinopathy (DR), high blood glucose drives chronic oxidative stress and inflammation that trigger alterations of the neurovascular balance finally resulting in vascular abnormalities and retinal cell death, which converge towards altered electroretinogram (ERG). In the last years, a growing body of preclinical evidence has suggested that nutrients with anti-inflammatory/antioxidant properties can be able to hamper DR progression since its very early stages. In the present study, we used a streptozotocin-induced rat model of DR, which mimics most aspects of the early stages of human DR, to test the preventive efficacy of a novel compound containing cyanidin-3-glucoside (C3G), verbascoside and zinc as nutrients with antioxidant and anti-inflammatory properties. Western blot, immunofluorescence and electroretinographic analyses demonstrated a dose-dependent inhibition of oxidative stress- and inflammation-related mechanisms, with a significant counterpart in preventing molecular mechanisms leading to DR-associated vasculopathy and its related retinal damage. Preventive efficacy of the compound on dysfunctional a- and b-waves was also demonstrated by electroretinography. The present demonstration that natural compounds, possibly as a consequence of vascular rescue following ameliorated oxidative stress and inflammation, may prevent the apoptotic cascade leading to ERG dysfunction, adds further relevance to the potential application of antioxidants as a preventive therapy to counteract DR progression.
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Affiliation(s)
| | - Rosario Amato
- Department of Biology, University of Pisa, Pisa, Italy
| | | | - Massimo Dal Monte
- Department of Biology, University of Pisa, Pisa, Italy.,Interdepartmental Research Center Nutrafood "Nutraceuticals and Food for Health", University of Pisa, Pisa, Italy
| | | | - Paola Bagnoli
- Department of Biology, University of Pisa, Pisa, Italy
| | - Maurizio Cammalleri
- Department of Biology, University of Pisa, Pisa, Italy.,Interdepartmental Research Center Nutrafood "Nutraceuticals and Food for Health", University of Pisa, Pisa, Italy
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Alpers DH, Young GP, Tran CD, Mortimer EK, Gopalsamy GL, Krebs NF, Manary MJ, Ramakrishna BS, Binder HJ, Brown IL, Miller LV. Drug-development concepts as guides for optimizing clinical trials of supplemental zinc for populations at risk of deficiency or diarrhea. Nutr Rev 2017; 75:147-162. [PMID: 28399577 DOI: 10.1093/nutrit/nuw065] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Studies on the efficacy of zinc supplementation for treatment or prevention of diarrhea have shown an inconsistent effect in populations at risk for zinc deficiency. Unlike drugs, which have no preexisting presence in the body, endogenous zinc must be assessed pharmacokinetically by isotope tracer studies. Although such methods have produced much data, very few studies have estimated the dose and the timing of dosing of zinc supplementation. This review examines drug kinetics used to establish the best dose, the timing of such doses, and the mechanism of action through pharmacodynamic markers and applies them, where possible, to zinc supplements. The findings reveal that little is known, especially in children at highest risk of zinc deficiency. Key data missing to inform proper dosing, whether for treatment of disease or for preventive nutrient supplementation, are noted. Addressing these uncertainties could improve study design, leading to future studies of zinc supplements that might be of greater benefit.
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Affiliation(s)
- David H Alpers
- School of Medicine, Washington University, St Louis, Missouri, USA
| | - Graeme P Young
- School of Medicine, Flinders University of South Australia, Adelaide, South Australia, Australia
| | - Cuong D Tran
- CSIRO Health and Biosecurity, Adelaide, South Australia, Australia.,School of Medicine, Faculty of Health Sciences, The University of Adelaide, South Australia, Australia
| | - Elissa K Mortimer
- School of Medicine, Flinders University of South Australia, Adelaide, South Australia, Australia
| | - Geetha L Gopalsamy
- School of Medicine, Flinders University of South Australia, Adelaide, South Australia, Australia.,CSIRO Health and Biosecurity, Adelaide, South Australia, Australia
| | - Nancy F Krebs
- Section of Nutrition, Department of Pediatrics, University of Colorado School of Medicine, Denver, Colorado, USA
| | - Mark J Manary
- School of Medicine, Washington University, St Louis, Missouri, USA
| | | | - Henry J Binder
- School of Medicine, Yale University, New Haven, Connecticut, USA
| | - Ian L Brown
- School of Medicine, Flinders University of South Australia, Adelaide, South Australia, Australia
| | - Leland V Miller
- Section of Nutrition, Department of Pediatrics, University of Colorado School of Medicine, Denver, Colorado, USA
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Roney N, Osier M, Paikoff SJ, Smith CV, Williams M, De Rosa CT. ATSDR evaluation of the health effects of zinc and relevance to public health. Toxicol Ind Health 2016; 22:423-93. [PMID: 17533814 DOI: 10.1177/0748233706074173] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
As part of its mandate, the Agency for Toxic Substances and Disease Registry (ATSDR) prepares toxicological profiles on hazardous chemicals found at Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) National Priorities List (NPL) sites, which have the greatest public health impact. These profiles comprehensively summarise toxicological and environmental information. This article constitutes the release of portions of the Toxicological Profile for Zinc. The primary purpose of this article is to provide public health officials, physicians, toxicologists, and other interested individuals and groups with an overall perspective on the toxicology of zinc. It contains descriptions and evaluations of toxicological studies and epidemiological investigations, and provides conclusions, where possible, on the relevance of toxicity and toxicokinetic data to public health. Toxicology and Industrial Health 2006; 22: 423-493.
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Affiliation(s)
- Nickolette Roney
- Agency for Toxic Substances and Disease Registry (ATSDR), US Department of Health and Human Services, Atlanta, GA, USA
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McIntyre CM, Monk HM. Medication absorption considerations in patients with postpyloric enteral feeding tubes. Am J Health Syst Pharm 2014; 71:549-56. [DOI: 10.2146/ajhp130597] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Affiliation(s)
| | - Heather M. Monk
- Neonatology, Department of Pharmacy, Children’s Hospital of Philadelphia, Philadelphia, PA
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Tubek S. Zinc supplementation or regulation of its homeostasis: advantages and threats. Biol Trace Elem Res 2007; 119:1-9. [PMID: 17914213 DOI: 10.1007/s12011-007-0043-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2007] [Revised: 11/30/1999] [Accepted: 03/01/2007] [Indexed: 11/28/2022]
Abstract
To accomplish its multifunctional biological roles, zinc requires precise homeostatic mechanisms. There are efficient mechanisms that regulate zinc absorption from the alimentary tract and its excretion by the kidney depending on the organism demands. The regulatory mechanisms of cellular zinc inflow, distribution, and zinc outflow are so efficient that symptoms of zinc deficiency are rare, and symptoms connected with its massive accumulation are even more rare. The efficiency of homeostatic mechanisms that prevent zinc deficiency or excessive zinc accumulation in the organism is genetically conditioned. It seems that an essential element of zinc homeostasis is the efficiency of zinc transmembrane exchange mechanisms. Intracellular free zinc concentration is higher than in extracellular space. Physiologically, the active outflow of zinc ions from the cell depends on the increase of its concentration in extracellular space. The ion pumps activity depends on the efficiency by which the cell manages energy. Considering the fact that zinc deficiency accelerates apoptosis and that excessive zinc accumulation inside cells results in a toxic effect that forces its death brings about several questions: Is intensification and acceleration of changes in zinc metabolism with age meaningful? Is there a real zinc deficiency occurring with age or in connection with the aforementioned pathological processes, or is it just a case of tissue and cell redistribution? When discussing factors that influence zinc homeostasis, can we consider zinc supplementation or regulation of zinc balance in the area of its redistribution? To clarify these aspects, an essential element will also be the clear understanding of the nomenclature used to describe changes in zinc balance. Zinc homeostasis can be different in different age groups and depends on sex, thus zinc dyshomeostasis refers to changes in its metabolism that deviate from the normal rates for a particular age group and sex. This concept is very ample and implies that zinc deficiency may result from a low-zinc diet, poor absorption, excessive loss of zinc, zinc redistribution in intra- and extracellular compartments, or a combination of these factors that is inadequate for the given age and sex group. Such factor or factors need to be considered for preventing particular homeostasis disorders (or dyshomeostasis). Regulation of zinc metabolism by influencing reversal of redistribution processes ought to be the main point of pharmacologic and nonpharmacologic actions to reestablish zinc homeostasis. Supplementation and chelation are of marginal importance and can be used to correct long-term dietary zinc deficiency or zinc poisoning or in some cases in therapeutic interventions. In view of its biological importance, the problem posed by the influence of zinc metabolism requires further investigation. To date, one cannot consider, for example, routine zinc supplementation in old age, because changes of metabolism with age are not necessarily a cause of zinc deficiency. Supplementation is warranted only in cases in which deficiency has been established unambiguously. An essential element is to prevent sudden changes in zinc metabolism, which lead to dyshomeostasis in the terms defined here. The primary prophylaxes, regular physical activity, efficient treatment of chronic diseases, are all elements of such prevention.
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Affiliation(s)
- Sławomir Tubek
- Faculty of Physical Education and Physiotherapy, Institute of Technology-Opole, Prószkowska Street 76, 45-758 Opole, Poland.
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Abi Khalil F, Hanocq M, Dubois J. A new method to estimate parameters of pharmacokinetics with enterohepatic circulation. Eur J Drug Metab Pharmacokinet 1993; 18:131-9. [PMID: 8243495 DOI: 10.1007/bf03188787] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
A new method of estimating pharmacokinetic parameters for enterohepatic recirculation models is presented. The algorithm, based on the simplex method, assures a convergence toward the minimum minimorum; provides reliable parameters, even in large numbers; and handles up to five cycle effects in five established models: IV, EV, mono-, bi- or tricompartmental. For each model, the reabsorption rate may be considered to be slow (characterised by a rate constant with a significant value) or instantaneous (an infinite rate constant). Two examples are given to illustrate the qualities of the software that incorporates this new algorithm. The first relates to the pharmacokinetics of zinc orally given to humans; the second treats the kinetics of alpha-methylDOPA given to dogs intra-arterially (note: values of plasma concentrations have been extracted from the literature).
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Affiliation(s)
- F Abi Khalil
- Institut de Pharmacie, Université Libre de Bruxelles, Belgium
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