Maternal zinc intakes and homeostatic adjustments during pregnancy and lactation.

Zinc plays critical roles during embryogenesis, fetal growth, and milk secretion, which increase the zinc need for pregnancy and lactation. Increased needs can be met by increasing the dietary zinc intake, along with making homeostatic adjustments in zinc utilization. Potential homeostatic adjustments include changes in circulating zinc, increased zinc absorption, decreased zinc losses, and changes in whole body zinc kinetics. Although severe zinc deficiency during pregnancy has devastating effects, systematic reviews and meta-analysis of the effect of maternal zinc supplementation on pregnancy outcomes have consistently shown a limited benefit. We hypothesize, therefore, that zinc homeostatic adjustments during pregnancy and lactation improve zinc utilization sufficiently to provide the increased zinc needs in these stages and, therefore, mitigate immediate detrimental effects due to a low zinc intake. The specific questions addressed are the following: How is zinc utilization altered during pregnancy and lactation? Are those homeostatic adjustments influenced by maternal zinc status, dietary zinc, or zinc supplementation? These questions are addressed by critically reviewing results from published human studies on zinc homeostasis during pregnancy and lactation carried out in different populations worldwide

Analysis of cellular responses of macrophages to zinc ions and zinc oxide nanoparticles: a combined targeted and proteomic approach

Two different zinc oxide nanoparticles, as well as zinc ions, are used to study the cellular responses of the RAW 264 macrophage cell line. A proteomic screen is used to provide a wide view of the molecular effects of zinc, and the most prominent results are cross-validated by targeted studies. Furthermore, the alteration of important macrophage functions (e.g. phagocytosis) by zinc is also investigated. The intracellular dissolution/uptake of zinc is also studied to further characterize zinc toxicity. Zinc oxide nanoparticles dissolve readily in the cells, leading to high intracellular zinc concentrations, mostly as protein-bound zinc. The proteomic screen reveals a rather weak response in the oxidative stress response pathway, but a strong response both in the central metabolism and in the proteasomal protein degradation pathway. Targeted experiments confirm that carbohydrate catabolism and proteasome are critical determinants of sensitivity to zinc, which also induces DNA damage. Conversely, glutathione levels and phagocytosis appear unaffected at moderately toxic zinc concentrations

Zinc Nutrition of Rice Plants as Influenced by Seed Germinated in Zinc Solutions

In recent years a physiological disorder of rice (Oryza sativa L.) seedlings growing in soils high in exchangeable calcium has been diagnosed as zinc deficiency. Calculations show that less than 30 g of zinc is needed to satisfy the nutrition of a hectare of 6-8-wk-old rice plants. Rice seed was soaked and germinated in dilute solutions of zinc ethylenediamine tetraacetate, zinc sulfate and zinc lignosulfonate prior to planting in greenhouse pots containing a zinc-deficient soil. The rice plants grown from the zinc-treated seed produced more growth and sorbed more zinc than rice plants grown from untreated seed

The Relationship between Zinc Intake and Serum/Plasma Zinc Concentration in Children: A Systematic Review and Dose-Response Meta-Analysis

Recommendations for zinc intake during childhood vary widely across Europe. The EURRECA project attempts to consolidate the basis for the definition of micronutrient requirements, taking into account relationships among intake, status and health outcomes, in order to harmonise these recommendations. Data on zinc intake and biomarkers of zinc status reported in randomised controlled trials (RCTs) can provide estimates of dose-response relationships which may be used for underpinning zinc reference values. This systematic review included all RCTs of apparently healthy children aged 1–17 years published by February 2010 which provided data on zinc intake and biomarkers of zinc status. An intake-status regression coefficient was calculated for each individual study and calculated the overall pooled and SE using random effects meta-analysis on a double log scale. The pooled dose-response relationship between zinc intake and zinc status indicated that a doubling of the zinc intake increased the serum/plasma zinc status by 9%. This evidence can be utilised, together with currently used balance studies and repletion/depletion studies, when setting zinc recommendations as a basis for nutrition policies

Zinc accumulation and utilisation by wine yeasts

The present study has focused on the accumulation of zinc by wine yeast strains of Saccharomyces cerevisiae during fermentation of both grape juice and chemically defined medium with different carbohydrates and at varying levels of zinc. The results have shown that zinc accumulation by wine yeast was very rapid with all zinc being removed from the medium by yeast cells within the first two hours. Zinc uptake was stimulated by the presence of sucrose. Zinc affected fermentation progress at defined levels, with optimal concentrations at 1.5–2.5 ppm, depending on yeast strain and zinc bioavailability. The bioavailability of metal ions in grape must and the roles of metals in wine yeast physiology are aspects poorly understood by enologists. In brewing, it has long been recognized that malt wort may be zinc deficient and brewers often carry out zinc supplementations to avoid sluggish and incomplete fermentations. In winemaking, zinc levels in grape musts may be compromised depending on the bioavailability of zinc ions in vineyard soils as well as treatments with fertilizers and fungicides during grape growing. As a consequence, sub-optimal zinc levels in grape musts may negatively influence the fermentative performance of yeasts. We believe that optimization of metal ion bioavailability will improve yeast fermentation performance in industrial processes and this study addresses some issues relating to zinc in enology

A Review of Dietary Zinc Recommendations

Background. Large discrepancies exist among the dietary zinc recommendations set by expert groups. Objective. To understand the basis for the differences in the dietary zinc recommendations set by the World Health Organization, the U.S. Institute of Medicine, the International Zinc Nutrition Consultative Group, and the European Food Safety Agency. Methods. We compared the sources of the data, the concepts, and methods used by the four expert groups to set the physiological requirements for absorbed zinc, the dietary zinc requirements (termed estimated and/or average requirements), recommended dietary allowances (or recommended nutrient intakes or population reference intakes), and tolerable upper intake levels for selected age, sex, and life-stage groups. Results. All four expert groups used the factorial approach to estimate the physiological requirements for zinc. These are based on the estimates of absorbed zinc required to offset all obligatory zinc losses plus any additional requirements for absorbed zinc for growth, pregnancy, or lactation. However, discrepancies exist in the reference body weights used, studies selected, approaches to estimate endogenous zinc losses, the adjustments applied to derive dietary zinc requirements that take into account zinc bioavailability in the habitual diets, number of dietary zinc recommendations set, and the nomenclature used to describe them. Conclusions. Estimates for the physiological and dietary requirements varied across the four expert groups. The European Food Safety Agency was the only expert group that set dietary zinc recommendations at four different levels of dietary phytate for adults (but not for children) and as yet no tolerable upper intake level for any life-stage group

Zinc inhibits TRPV1 to alleviate chemotherapy-induced neuropathic pain

Zinc is a transition metal that has a long history of use as an anti-inflammatory agent. It also soothes pain sensations in a number of animal models. However, the effects and mechanisms of zinc on chemotherapy-induced peripheral neuropathy remain unknown. Here we show that locally injected zinc markedly reduces neuropathic pain in male and female mice induced by paclitaxel, a chemotherapy drug, in a TRPV1-dependent manner. Extracellularly applied zinc also inhibits the function of TRPV1 expressed in HEK293 cells and mouse DRG neurons, which requires the presence of zinc-permeable TRPA1 to mediate entry of zinc into the cytoplasm. Moreover, TRPA1 is required for zinc-induced inhibition of TRPV1-mediated acute nociception. Unexpectedly, zinc transporters, but not TRPA1, are required for zinc-induced inhibition of TRPV1-dependent chronic neuropathic pain produced by paclitaxel. Together, our study demonstrates a novel mechanism underlying the analgesic effect of zinc on paclitaxel-induced neuropathic pain that relies on the function of TRPV1

Costs of Chronic Waterborne Zinc Exposure and the Consequences of Zinc Acclimation on the Gill/Zinc Interactions of Rainbow Trout in Hard and Soft Water

Juvenile rainbow trout were exposed to zinc in both moderately hard water (hardness 5 120 mg CaCO3/L, pH = 8.0, Zn = 150 μg/L or 450 μg/L) and soft water (hardness = 20 mg CaCO3/L, pH = 7.2, Zn = 50 μg/L or 120 μg/L) for 30 d. Only the 450 mg/L zinc–exposed fish experienced significant mortality (24% in the first 2 d). Zinc exposure caused no effect on growth rate, but growth affected tissue zinc levels. Whole body zinc levels were elevated, but gills and liver showed no consistent increases relative to controls over the 30-d. Therefore, tissue zinc residues were not a good indicator of chronic zinc exposure. After the 30-d exposure, physiological function tests were performed. Zinc was 5.4 times more toxic in soft water (control 96 h LC50s in hard and soft water were 869 μg/L and 162 μg/L, respectively). All zinc-exposed trout had acclimated to the metal, as seen by an increase in the LC50 of 2.2 to 3.9 times over that seen in control fish. Physiological costs related to acclimation appeared to be few. Zinc exposure had no effect on whole body Ca2+ or Na+ levels, on resting or routine metabolic rates, or on fixed velocity sprint performance. However, critical swimming speed (UCrit) was significantly reduced in zinc-exposed fish, an effect that persisted in zinc-free water. Using radioisotopic techniques to distinguish new zinc incorporation, the gills were found to possess two zinc pools: a fast turnover pool (T1/2 = 3–4 h) and a slow turnover pool (T1/2 = days to months). The fast pool was much larger in soft water than in hard water, but at most it accounted for \u3c3.5% of the zinc content of the gills. The size of the slow pool was unknown, but its loading rate was faster in soft water. Chronic zinc exposure was found to increase the size of the fast pool and to increase the loading rate of the slow pool