Zinc Absorption Research Articles

Exogenous Phytase Added to Lipid Based Nutrient Supplements Increases Fractional and Total Absorption of Zinc Among Young Gambian Children: A Randomized Controlled Trial (OR07-01-19)

ObjectivesDietary phytate inhibits zinc absorption from composite meals in adults. The objective of this study was to investigate the efficacy of adding exogenous phytase to a small-quantity lipid based nutrient supplement (SQ-LNS) on zinc absorption among young children. MethodsIn a double-blind randomized controlled trial, intra-individual differences in fractional and total absorption of zinc (FAZ and TAZ, respectively) from SQ-LNS with and without phytase were measured in 30 asymptomatic 18–23 month old children in the Kiang West district of The Gambia. Using a cross-over design, children received for one day each test meals of a millet-based porridge with 20 g SQ-LNS containing 8 mg zinc and either: 1) exogenous phytase (∼500 phytase units (FTU)) or 2) no exogenous phytase. The test meals were provided on consecutive days in randomized order. FAZ was measured using a dual-stable isotope tracer ratio technique with 67 Zn and 70 Zn as oral tracers, randomized independently of SQ-LNS product, and 68 Zn as the intravenous tracer. TAZ was calculated as the product of total dietary zinc (TDZ) intake from test meals (i.e., porridge, SQ-LNS and stable isotope) and FAZ. FAZ and TAZ were compared for meals with and without phytase using mixed-models ANOVA with product, study day, and oral isotope allocation as fixed effects and individual child as a random effect. ResultsTwenty-six participants completed the study. The prevalence of stunting, underweight and wasting were 20%, 30% and 13%, respectively; no children had low plasma zinc concentrations (< 65 μg/dL). TDZ and phytate intakes from the test meals were 7.2 ± 2.2 mg and 182.9 ± 64.7 mg, respectively (phytate: zinc molar ratio = 2.4 ± 0.2). Mean FAZ increased from 8.6 ± 1.3% to 16.0 ± 1.3% when exogenous phytase was added to the SQ-LNS product (P = 0.0002). Mean TAZ from porridge test meals containing SQ-LNS with phytase was more than double that from test meals containing SQ-LNS without phytase (1.12 ± 0.07 mg and 0.52 ± 0.07 mg, respectively; P < 0.0001). ConclusionsThe addition of exogenous phytase to a meal of millet-based porridge with SQ-LNS improved both FAZ and TAZ. These results suggest that phytate reduction may be an important strategy to improve zinc absorption among young children. Funding SourcesNutriset, SAS.

Anti-nutritional and toxicological properties of Balanites aegyptiaca: a review

Edible wild plants and their products have played a substantial role in tackling the increasing gap between population growth and food supply. This article reviewed the scientific information on the anti-nutritional and toxicological properties of Balanites aegyptiaca (desert date). Systematic literature search shows the plant to contain saponin, tannins, oxalate and phytic acid that have been known to have adverse effects on health through inhibition of biomolecules digestion, important enzymes, iron, calcium and zinc absorption. From nutritional point of view, anti-nutrients are substances that interfere with normal growth and uptake of nutrients, reproduction and health, and when consumed regularly in amount found in a normal component of diet is considered harmful and toxic. Knowledge regarding ways and techniques to lower the content of anti-nutritional factors in B. aegyptiaca is needed for health and well-being of the population.Keywords: B. aegyptiaca, toxicity, nutrition

Uptake and exportation of micronutrients in high productivity corn fields

High yield corn has an increased demand for micronutrients, which requires updating knowledge of the nutritional demand patterns of the crop, especially under high production conditions. The objective of the currentstudy was therefore to determine the absorption and export patterns of copper (Cu), manganese (Mn), zinc (Zn) and iron (Fe) for high yield corn crops. Fifteen corn fields with high productive potential were sampled in the Alto Paranaíba, region, Minas Gerais, in the agricultural year 2014-2015. The following&#x0D; variables were evaluated: productivity, plant population, rows of grain per ear, grain per row, grain per ear, mass of one thousand grains, vegetation dry mass, dry mass of grains and total dry mass of the plant, besides the accumulation of micronutrients in the vegetative part and grains, and total micronutrient accumulation&#x0D; per whole plant. The grain and Cu, Mn, Zn and Fe harvest indices were also calculated. The data were submitted to descriptive statistics, Pearson coefficient linear correlation was calculated at the to 5% level and submitted to regression analysis. Cu and Zn absorption and export increase linearly with increased&#x0D; productivity. Micronutrient accumulation in high productivity maize is, in decreasing order, in the vegetative part: Fe&gt; Mn&gt; Zn&gt; Cu; while in the grains and in the whole plant: Fe&gt; Zn&gt; Mn&gt; Cu. Zn is the micronutrient with the highest harvest index.

Zinc Absorption From Agronomically Biofortified Wheat Is Similar to Post-Harvest Fortified Wheat and Is a Substantial Source of Bioavailable Zinc in Humans

Limited data exist on human zinc absorption from wheat biofortified via foliar (FBW) or root (hydroponically fortified wheat, HBW) zinc application. Stable isotope labels added at point of consumption (extrinsic labeling) might not reflect absorption from native zinc obtained by intrinsic labeling. We measured fractional and total zinc absorption (FAZ, TAZ) in FBW and HBW wheat, compared with control wheat (CW) and fortified wheat (FW). The effect of labeling method was assessed in HBW (study 1), and the effect of milling extraction rate (EXR, 80% and 100%) in FBW (studies 2 and 3). Generally healthy adults (n=71, age: 18-45 y, body mass index: 18.5-25 kg/m2) were allocated to 1 of the studies, in which they served as their own controls. In study 1, men and women consumed wheat porridges colabeled intrinsically and extrinsically with 67Zn and 70Zn. In studies 2 and 3, women consumed wheat flatbreads (chapatis) labeled extrinsically. Zinc absorption was measured with the oral to intravenous tracer ratio method with a 4-wk wash-out period between meals. Data were analyzed with linear mixed models. In study 1 there were no differences in zinc absorption from extrinsic versus intrinsic labels in either FW or HBW. Similarly, FAZ and TAZ from FW and HBW did not differ. TAZ was 70-76% higher in FW and HBW compared with CW (P<0.01). In studies 2 and 3, TAZ from FW and FBW did not differ but was 20-48% higher compared with CW (P<0.001). Extraction rate had no effect on TAZ. Colabeling demonstrates that extrinsic zinc isotopic labels can be used to accurately quantify zinc absorption from wheat in humans. Biofortification through foliar zinc application, root zinc application, or fortification provides higher TAZ compared with unfortified wheat. In biofortified wheat, extraction rate (100-80%) has a limited impact on total zinc absorption. These studies were registered on clinicaltrials.gov (NCT01775319).

The Effect of Magnesium, Zinc, and Selenium, Used Alone or in Combination, on Strength and Anabolic Hormone Levels in Rats

BackgroundMagnesium (Mg), zinc (Zn), and selenium (Se) are essential minerals that play an important role in the production of anabolic hormones that are vital for male sexual function, fertility, strength, and athletic performance. Deficiency in these minerals is associated with a decline in levels of anabolic hormones, such as testosterone and insulin‐like growth factor 1 (IGF‐1). Testosterone levels also begin to decline in most men after age 30, which may contribute to various adverse conditions including diabetes, reduced bone and muscle mass, impaired sexual function, and decreased energy.PurposeThis study investigated the effect of Mg‐N21 (a novel magnesium complex), zinc picolinate (ZnPic), and selenomethionine (SeMet) on hormone levels, mineral absorption, and strength in rats fed a high‐fat diet.MethodsForty‐two male Wistar rats (age: 8 weeks, weight: 180 ± 20 g) were divided into six groups as follows: 1) Control (no treatment), 2) HFD‐Control (fed a high‐fat diet), 3) HFD+Mg‐N21 (58.44 mg elemental Mg/kg diet, a 100 mg human equivalent dose (HED)), 4) HFD+ZnPic (17.53 mg elemental Zn/kg diet, a 30 mg HED), 5) HFD+SeMet (58.44 μg elemental Se/kg diet, a 0.1 mg HED), 6) HFD+Mg‐N21+ZnPic+SeMet (MZS). All treatments were administered daily as an oral supplement for 8 weeks. Muscle strength was assessed using a grip strength meter. After 8 weeks, rats were sacrificed, and serum and tissue samples were obtained for analysis.ResultsResults showed that serum testosterone levels were highest in the MZS group compared to all other treatment groups (Figure 1; p&lt;0.05). Compared to the HFD‐Control group, testosterone levels were 105% higher in the MZS group. Serum levels of follicle‐stimulating hormone (FSH), luteinizing hormone (LH), sex hormone‐binding globulin (SHBG), and insulin‐like growth factor 1 (IGF‐1) were highest in the MZS group compared to all other treatment groups (p&lt;0.05). Zinc, magnesium, and selenium absorption, retention, and levels (serum, liver, and brain) were significantly higher in the MZS group compared to the HFD‐Control group (p&lt;0.05). Zinc absorption and retention, and selenium retention were significantly higher when rats were given MZS compared to the individual nutrients alone (p&lt;0.05). Grip strength and the grip strength to body weight (GS/BW) ratio were significantly higher in the MZS group compared to all treatment groups (p&lt;0.05) but did not differ from the HFD+Mg‐N21 group. In the MZS group, grip strength and the GS/BW ratio increased by 58% and 68% respectively, over the HFD‐Control group (p&lt;0.05).ConclusionsThe results of this preclinical study demonstrate that the combination of Mg‐N21, zinc picolinate, and selenomethionine is more beneficial than the individual ingredients alone in raising anabolic hormone levels and muscle strength. These results may be of interest to aging men, since anabolic hormone levels decline with age, as well as men of all ages looking to raise anabolic hormone levels to benefit sexual function, strength, and energy.Support or Funding InformationThis study was funded by Nutrition 21, LLC.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Malabsorption of metals and intestinal parasite infections cause health problems and lower birth rates in the American Bison on the Fort Peck Indian Reservation

BackgroundHerds of American Bison have been raised on pastures of different Indian Reservations in Montana. It has been discovered that many of these Bison have serious health problems related to malnutrition causing lower birth rates. Plants on these reservations absorb unusually high levels of selenium and molybdenum which the animals feed on. Previous studies indicate metals such as copper are necessary for proper health and birthrates. Metals such as Copper, Zinc and Iron are necessary for normal conception rates and will cause retarded growth of the offspring. In addition, poor calving rates in apparently healthy bison with adequate protein and energy in diets might simply be from the different metal deficiencies. We have successively been able to isolate liver samples and fecal samples from Bison on the Fort Peck Indian Reservation to compare with other herds in Montana.HypothesisDecreased absorption of copper, zinc and iron is due to increased absorption of selenium and molybdenum. These difficiencies along with parasitic infections are causing health problems in the bison herds on the Fort Peck Reservation.MethodsWhen Two different herds on the Fort Peck Reservation were tested. One was a cultural herd that is 100% genes and the other is a business herd that contains beef genes. From both herds when the animals are euthanized liver samples and fecal samples are removed for analysis. Body scores were taken to access the states of malnutrition and number of offspring were counted to access birthrates.ResultsLiver tissue specimens collected from bison bulls harvested from the business herd were tested for essential trace mineral levels as well as for the presence of toxic elements. Trace mineral imbalances were detected. Elevated molybedenum (MO) was evident. Elevated Mo can deplete liver copper (Cu) and increase Cu‐molybdenate complexes in plasma or serum. Deficient levels of Cu, manganese and zinc were evident. In addition We determined that bison in the cultural herd were either free of internal parasites or had low burdens of internal parasites. The testing of 22 bison fecal samples found 7 samples to have undetectable ova or parasites per gram of feces. The remaining 15 samples had low levels of Strongyle sp. type ova (0.4–7.78 ova/gram of feces). Three of the 15 samples in addition to Strongyle sp. type ova, had Trichuris sp. (0.4 ova/gram), Nematodirus sp. (0.2–0.67 ova/gram), and/or Coccidia (0.6 ova/gram). In contrast, moderate to heavy burdens of internal parasites were commonly present in bison in conventional herds that we have studied to date.ConclusionsMalabsorption of nutrients such as copper may be caused by increased absorption of selenium, molybdenum or zinc as well as infections from parasites in the Bison digestive tract. We believe these health problems contribute to decreased weights and birthrates of the Bison on the Fort Peck Indian Reservation.Support or Funding InformationThis research is supported by a USDA grant.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Promoting the use of locally produced crops in making cereal-legume-based composite flours: An assessment of nutrient, antinutrient, mineral molar ratios, and aflatoxin content

Cassava, rice, and banana flours were used individually to replace wheat flour in cereal-legume-based composite flours. The proximate composition, mineral content, antinutritional effect, mineral molar ratios, and aflatoxin level were investigated. Replacing wheat flour with rice flour significantly (P < 0.05) improved protein, fat, potassium, and phosphorus content in samples. The molar ratios of phytate or oxalate to minerals (calcium and zinc) in all composite flours were lower than the reported critical values, except phytate to iron. However, all samples, except full replacement by rice flour, might not provide adequate zinc bioavailability when the effect of calcium and phytate on zinc absorption was collectively considered. Although all composite flours were contaminated with aflatoxins, only the control composed of wheat flour did not meet the EU regulatory threshold (4.0 µg/kg) for total aflatoxins. The findings showed that nutritional properties and aflatoxin content of composite flours can be improved by replacement with local crops.

An extracellular histidine-containing motif in the zinc transporter ZIP4 plays a role in zinc sensing and zinc-induced endocytosis in mammalian cells

Zinc is an essential trace element that serves as a cofactor for enzymes in critical biochemical processes and also plays a structural role in numerous proteins. Zinc transporter ZIP4 (ZIP4) is a zinc importer required for dietary zinc uptake in the intestine and other cell types. Studies in cultured cells have reported that zinc stimulates the endocytosis of plasma membrane-localized ZIP4 protein, resulting in reduced cellular zinc uptake. Thus, zinc-regulated trafficking of ZIP4 is a key means for regulating cellular zinc homeostasis, but the underlying mechanisms are not well understood. In this study, we used mutational analysis, immunoblotting, HEK293 cells, and immunofluorescence microscopy to identify a histidine-containing motif (398HTH) in the first extracellular loop that is required for high sensitivity to low zinc concentrations in a zinc-induced endocytic response of mouse ZIP4 (mZIP4). Moreover, using synthetic peptides with selective substitutions and truncated mZIP4 variants, we provide evidence that histidine residues in this motif coordinate a zinc ion in mZIP4 homodimers at the plasma membrane. These findings suggest that 398HTH is an important zinc-sensing motif for eliciting high-affinity zinc-stimulated endocytosis of mZIP4 and provide insight into cellular mechanisms for regulating cellular zinc homeostasis in mammalian cells.

Effects of a moderate iron overload and its interaction with yacon flour, and/or phytate, in the diet on liver antioxidant enzymes and hepatocyte apoptosis in rats

The effect of moderate Fe overload in the diet and its interaction with phytate, and/or yacon flour (YF), recognized as an inhibitor, and facilitator, of Fe absorption, respectively, was evaluated in healthy rats. For this purpose the following parameters were analyzed: (1) apparent iron (Fe), copper (Cu) and zinc (Zn) absorption; (2) blood Fe; (3) blood lipids (cholesterol, tryacylglicerol); (4) blood AST and ALT; (5) liver histology (histopathology, hemosiderin depots, apoptosis index; (6) liver fatty acid incorporation; (7) liver antioxidant enzyme activity. Moderate Fe overload may cause change in some liver markers (hemosiderin depots, apoptosis index and GPx) and blood lipids (total cholesterol and VLDL) and the interaction with yacon flour, and phytate, in the Fe overloaded diets may exert a protective effect on these alterations.

Zn-DTSM, A Zinc Ionophore with Therapeutic Potential for Acrodermatitis Enteropathica?

Acrodermatitis enteropathica (AE) is a rare disease characterised by a failure in intestinal zinc absorption, which results in a host of symptoms that can ultimately lead to death if left untreated. Current clinical treatment involves life-long high-dose zinc supplements, which can introduce complications for overall nutrient balance in the body. Previous studies have therefore explored the pharmacological treatment of AE utilising metal ionophore/transport compounds in an animal model of the disease (conditional knockout (KO) of the zinc transporter, Zip4), with the perspective of finding an alternative to zinc supplementation. In this study we have assessed the utility of a different class of zinc ionophore compound (zinc diethyl bis(N4-methylthiosemicarbazone), Zn-DTSM; Collaborative Medicinal Development, Sausalito, CA, USA) to the one we have previously described (clioquinol), to determine whether it is effective at preventing the stereotypical weight loss present in the animal model of disease. We first utilised an in vitro assay to assess the ionophore capacity of the compound, and then assessed the effect of the compound in three in vivo animal studies (in 1.5-month-old mice at 30 mg/kg/day, and in 5-month old mice at 3 mg/kg/day and 30 mg/kg/day). Our data demonstrate that Zn-DTSM has a pronounced effect on preventing weight loss when administered daily at 30 mg/kg/day; this was apparent in the absence of any added exogenous zinc. This compound had little overall effect on zinc content in various tissues that were assessed, although further characterisation is required to more fully explore the cellular changes underlying the physiological benefit of this compound. These data suggest that Zn-DTSM, or similar compounds, should be further explored as potential therapeutic options for the long-term treatment of AE.

Zinc Absorption from Micronutrient Powders Is Low in Bangladeshi Toddlers at Risk of Environmental Enteric Dysfunction and May Increase Dietary Zinc Requirements

ABSTRACTBackgroundEnvironmental enteric dysfunction (EED), a chronic inflammatory disorder of the small bowel, is suspected to impair absorption of micronutrients, including zinc.ObjectiveThe objective of this study was to compare zinc absorption from micronutrient powder (MNP) over a range of zinc doses in young children screened for EED with use of the lactulose:mannitol ratio (L:M).MethodsBangladeshi children aged 18–24 mo, grouped according to high and low L:M (≥0.09 and <0.09, respectively), were randomly assigned to MNP with 0, 5, 10, or 15 mg Zn/sachet (10 subjects per dose per L:M group). Over a day, fractional absorption of zinc was measured from an MNP-fortified meal and from unfortified meals with stable isotope tracers; total daily absorbed zinc (TAZ, milligrams per day) was determined as the primary outcome. Secondary outcomes included investigation of relations of TAZ to intake, to physiologic requirement, and to other variables, including biomarkers of systemic and intestinal inflammation, using nonlinear models. TAZ was also compared with published data on child zinc absorption.ResultsIn 74 subjects who completed the study, zinc absorption did not differ by L:M grouping. Most biomarkers of intestinal inflammation were elevated in both L:M groups. For combined L:M groups, mean ± SD TAZ for each MNP dose (0, 5, 10, and 15 mg/sachet) was 0.57 ± 0.30, 0.68 ± 0.31, 0.90 ± 0.43, and 1.0 ± 0.39 mg/d, respectively (P = 0.002), and exceeded the estimated physiologic requirement only for the 10- and 15-mg MNP doses. Zinc absorption was notably lower at all intake levels compared with published data (P < 0.0001) and was inversely related to serum α-1 acid glycoprotein and to fecal Entamoeba histolytica (P = 0.02).ConclusionResults indicate impaired absorption of zinc, which may predispose to zinc deficiency in young children with evidence of enteropathy. These findings suggest that current doses of zinc in MNP may be insufficient to yield zinc-related preventative benefits in similar settings. This study is registered at clinicaltrials.gov as NCT02758444.

Assessing the Bioavailability of Zinc and Indole Compounds from Mycelial Cultures of the Bay Mushroom Imleria badia (Agaricomycetes) Using In Vitro Models.

Zinc and indole compounds demonstrate anti-inflammatory, antidepressant, and antioxidant activity. Edible mushrooms are good sources of these substances. Therefore, in this study, we aimed to study the accumulation, release, and absorption of zinc and indole compounds from mycelial cultures of Imleria badia species using in vitro models. Samples were analyzed using the atomic absorption spectroscopy method and the reversed-phase high-performance liquid chromatography method. The highest quantities of zinc were detected in the material grown on zinc hydrogen aspartate-enriched media (176.01 mg/100 g dry weight [d.w.]). In addition, the quantity of zinc in the control biomass was approximately 12.13 mg/100 g d.w. After passive transport, the amount of zinc was detected to be around 1.40 mg/100 g d.w., whereas after active transport with CaCo-2 cells, the quantity of zinc ranged from 0.46 mg/100 g d.w. to 12.72 mg/100 g d.w. Among the organic compounds, four indole compounds were qualitatively identified, including 5-hydroxy-l-tryptophan, melatonin, l-tryptophan, and 5-methyltryptamine. These results indicate that mushrooms and their in vitro cultures not only synthesize and accumulate these compounds, but also potentially release them into the gastrointestinal tract where they can be absorbed by the human body, which is reflected as a specific health benefit.

Leafy Vegetables as Potential Pathways to Heavy Metal Hazards

The effect of anthropogenic activity relating to industrial and economic development has had a detrimental impact on the environment and human health, and hence the need for continued research. Five common African vegetables—Murraya koenigii, Ocimum gratissimum, Amaranthus hybridus, Capsicum annuum and Moringa oleifera were used to study absorption of Lead, Cadmium, Cobalt and Zinc from soils inoculated with metal ions. 0.1 M and 0.5 M solutions of the metal ions were used in the inoculation. Each of the plants was collected in the first instance at 8 weeks, and then at 10 weeks of inoculating. Atomic Absorption spectrophotometer was used to determine the metal ions concentrations absorbed in the plants. Cd2+ was most and Moringa oleifera the least absorbed of the four metal ions, with a highest value of 34.801 ± 0.805 mg/kg occurring in Capsicum annuum. Co2+ was the least absorbed of the four metal ions, Amaranthus hybridus showed highest absorption of Co2+ with mean absorption values of 5.566 ± 0.324 mg/kg and 5.670 ± 0.210 mg/kg for 0.1 M and 0.5 M solution of Co2+ respectively. Ocimum gratissimum absorbed Pb2+ most with the highest mean absorption of 5.290 ± 0.180 mg/kg and 6.354 ± 0.366 mg/kg for 0.1 M and 0.5 M respectively. Absorption increased as the concentration of the inoculant solution increased for all the plants, and decreased on moving from 8 weeks’ to 10 weeks’ for all the plants except Moringa oleifera. This could as a result of Phytovolatilization against the report of Padmavathiamma and Li, 2007 [1] that phytovolatilization occurs in As, Hg and Se. Ocimum gratissimum showed highest absorption with the mean value of 9.334 ± 0.312 mg/kg, when the inoculants concentration increased to 0.5 M, Capsicum annuum showed highest absorption with mean absorption value of 9.916 ± 0.614 mg/kg at 10th week. Also absorption increased as the concentration of the inoculant solution increased, and also on moving from 8 weeks’ to 10 weeks’ for all the plants. From the results obtained, all the vegetables absorbed significant amounts of the metal ions. This raises a lot of health concern about the vegetables consumed in most developing countries like Nigeria where vegetables are grown anywhere, without any consideration of the environment.

52 The influence of supplemental zinc and dietary energy level on mineral retention of beef steers.

The objective was to determine if Zn retention improved with supplemental Zn above recommended concentrations with increasing growth rate. Angus steers (n = 32; 309 ± 4.2 kg BW) with Genemax gain scores of 3, 4, or 5 were utilized in a 2 × 2 factorial arrangement (8 steers/treatment). Steers were blocked by BW within growing diets to one of two Zn strategies (ZNTRT) 1) no supplemental Zn (analyzed 36 mg Zn/kg DM; CON) or 2) supranutritional Zn (analyzed 153 mg Zn/kg DM; SUPZN), fed for 60-d and then assigned to a dietary energy strategy (ENERGY) to emulate two different growth rates representing ~1.5 kg ADG (LOW) or ~2 kg ADG (HI). Beginning on d-60, HI steers were transitioned to HI for 14-d. On d 74, steers (4 groups; 8 steers/group; 2 steers/treatment) moved to metabolism crates and adapted for 10-d, followed by 5-d of total fecal and urine collection. Data were analyzed as a 2 × 2 factorial in Proc Mixed of SAS with ZNTRT×ENERGY×group as random; steer was experimental unit. No ZNTRT and ENERGY interactions were detected (P ≥ 0.12). Dry matter digestibility tended to increase due to SUPZN (P = 0.10). Water intake was lesser (P ≤ 0.03) in SUPZN vs. CON and LOW vs. HI; urine output tended (P = 0.08) to decrease in LOW vs. HI. Copper apparent absorption was unaffected by ZNTRT (P = 0.28), but Cu apparent absorption increased in LOW (22.1%) vs. HI (15.3%; P = 0.04). SUPZN increased (P < 0.01) intake and retention of Zn (377 vs. 100 mg/d) and decreased Zn apparent absorption vs. CON (30.9 vs. 25.5%; P = 0.04). Zinc apparent absorption (32.3 vs. 24.1%) increased in LOW vs. HI (P < 0.01). Zinc absorption and retention appear to be influenced by diet energy concentration and more positively impacted by LOW energy diet.

53 Evaluation of nutrient digestibility, apparent absorption and retention of zinc in lambs supplemented with zinc from zinc hydroxychloride, zinc sulfate or zinc methionine.

53 Evaluation of nutrient digestibility, apparent absorption and retention of zinc in lambs supplemented with zinc from zinc hydroxychloride, zinc sulfate or zinc methionine.

Zinc in Ruminants: Metabolism and Homeostasis

Zinc is one of the most studied minerals of the twenty-first century as it is practically involved in every function of the body. The importance of zinc has earned it the epithet “calcium of twenty-first century.” However, the bioavailability of zinc depends on the source of zinc and the subsequent processes of digestion, absorption and metabolism. Zinc from organic sources tends to be more available to animals than from inorganic sources. The complex gastrointestinal physiology of ruminants makes these processes even more intricate. Zinc in the rumen interacts with other substances altering its fate. Absorption of zinc from the gastrointestinal tract (GIT) was a mystery until the discovery of zinc transporter proteins. These discoveries opened new gates of wisdom and understanding about the tumultuous journey of zinc molecules through the complex GIT of ruminants. The decade-old concepts of zinc homeostasis largely based on the zinc complexes are jostling through the new theories with the focus on the free zinc ions. The present review briefly elucidates the processes of metabolism and homeostasis of zinc in ruminants.

Effects of tapeworm infection on absorption and excretion of zinc and cadmium by experimental rats.

The main objective of this study was to determine how rat tapeworms affect the excretion of zinc and cadmium through rat feces. Male rats (Rattus norvegicus var. alba) were divided into four groups, and the experiment was conducted over a 6-week period. The control groups (00; 0T) were provided with a standard ST-1 rodent mixture and received 10.5mg of Zn/week. Groups P0 and PT were fed a mixture supplemented with the hyperaccumulating plant Arabidopsis halleri at a dosage of 123mg Zn/week and 2.46mg Cd/week. Groups 0T and PT were infected with the rat tapeworm (Hymenolepis diminuta). Fecal samples were collected 24h post exposure. Zinc and cadmium concentrations in rat feces were analyzed using inductively coupled plasma optical emission spectrometry. Tapeworm presence decreased the amount of metals excreted through the feces of the host throughout the entire experiment, with the exception of 1week (control group). No statistically significant differences between zinc excretion rates in the control groups (00 and 0T) were detected at any time throughout the experiment. A statistically significant difference between zinc excretion rates (p < 0.05) in the exposed groups (P0 and PT) was detected in 2 of the 6 monitored weeks. Group PT excreted significantly less cadmium (p < 0.01) than group P0 did in three of the 6weeks. Overall, our results indicate that tapeworms are able to influence the excretion of metals by their host. Tapeworms accumulate metals from intestinal contents. It is not clear whether tapeworms carry out this process before the host tissues absorb the metals from the intestines or the tapeworms accumulate metals excreted from the body of the host back to the intestines. Most likely, it is a combination of both phenomena.

Zinc as an Essential Nutritional Component of Human Body: A Systemic Review

Introduction: Second to iron, zinc, which is widely distributed in the human body, is the most abundant element in human body. The human body has about 2 to 3 grams of zinc, with the highest concentrations in the liver, pancreas, kidneys, bones and muscles. Other tissues with a higher concentration of zinc include parts of the eye, prostate gland, spermatozoa, skin, hair, fingernail and toenails. Methods: Searches were conducted by two independent researchers in international (PubMed, Web of science, Scopus and Google scholar) and national (SID, Magiran) databases for related studies from the inception of the databases to September 2017 (without time limitation) in English and Persian languages. To ensure literature saturation, the reference lists of included studies or relevant reviews identifed through the search were scanned. Discussion: Absorption and excretion of zinc are carried out through hemostatic mechanisms that are not quite well known yet. The absorption mechanism consists of two paths. Albumin is the most important zinc plasma carrier. The amount transported in blood, in addition to zinc, depends on the availability of albumin. Zinc is a single intracellular ion with structural, catalytic and regulatory roles. Zinc plays important structural roles as part of a multi-protein structure. Key words: Zinc , essential nutritional ,component , human body

Approaches used to estimate bioavailability when deriving dietary reference values for iron and zinc in adults.

This review aims to describe approaches used to estimate bioavailability when deriving dietary reference values (DRV) for iron and zinc using the factorial approach. Various values have been applied by different expert bodies to convert absorbed iron or zinc into dietary intakes, and these are summarised in this review. The European Food Safety Authority (EFSA) derived zinc requirements from a trivariate saturation response model describing the relationship between zinc absorption and dietary zinc and phytate. The average requirement for men and women was determined as the intercept of the total absorbed zinc needed to meet physiological requirements, calculated according to body weight, with phytate intake levels of 300, 600, 900 and 1200 mg/d, which are representative of mean/median intakes observed in European populations. For iron, the method employed by EFSA was to use whole body iron losses, determined from radioisotope dilution studies, to calculate the quantity of absorbed iron required to maintain null balance. Absorption from the diet was estimated from a probability model based on measures of iron intake and status and physiological requirements for absorbed iron. Average dietary requirements were derived for men and pre- and post-menopausal women. Taking into consideration the complexity of deriving DRV for iron and zinc, mainly due to the limited knowledge on dietary bioavailability, it appears that EFSA has made maximum use of the most relevant up-to-date data to develop novel and transparent DRV for these nutrients.

Implications of phytate in plant-based foods for iron and zinc bioavailability, setting dietary requirements, and formulating programs and policies.

Plant-based diets in low-income countries (LICs) have a high content of phytic acid (myo-inositol hexaphosphate [InsP6]) and associated magnesium, potassium, and calcium salts. Together, InsP6 acid and its salts are termed "phytate" and are potent inhibitors of iron and zinc absorption. Traditional food processing can reduce the InsP6 content through loss of water-soluble phytate or through phytase hydrolysis to lower myo-inositol phosphate forms that no longer inhibit iron and zinc absorption. Hence, some processing practices can reduce the need for high-dose iron fortificants in plant-based diets and alleviate safety concerns. Dietary phytate-to-iron and phytate-to-zinc molar ratios are used to estimate iron and zinc bioavailability and to identify dietary iron and zinc requirements according to diet type. The European Food Safety Authority has set adult dietary zinc requirements for 4 levels of phytate intake, highlighting the urgent need for phytate food composition data. Such data will improve the ability to estimate the prevalence of inadequate zinc intakes in vulnerable groups in LICs, which will facilitate implementation of targeted policies to alleviate zinc deficiency.