Dietary Zinc Requirement Research Articles

Dietary zinc requirement of juvenile stinging catfish Heteropneustes fossilis based on growth performance, haematology, and tissue mineral composition

This investigation was done to determine how much zinc (Zn) the stinging catfish, Heteropneustes fossilis, needs in its diet. Five isonitrogenous (34.5% protein) and isolipidic (6.0% lipid) diets were prepared to contain graded levels of Zn (0, 10, 20, 30, and 40 mg kg−1), supplied as zinc sulfate (ZnSO4·7H2O), and referred to as Zn0, Zn10, Zn20, Zn30, and Zn40, respectively. A total of 600 fish (initial body weight: 1.41 ± 0.02 g) were stocked in 15 glass aquaria (40 fish/aquarium), each with 180 L water capacity. For ten weeks, each diet was hand fed to three groups of fish twice daily until they appeared satisfied. The highest weight gain and specific growth rate, and lowest feed conversion ratio were recorded in fish fed with a 30 mg Zn kg−1 diet. Zn contents in bone and muscle linearly increased up to 30 mg kg−1 Zn and then remained stable, while iron (Fe) and copper (Cu) contents in bone and muscle had an inverse pattern with the inclusion level of dietary Zn. Increasing dietary Zn levels up to 30 mg kg−1 was found to improve values of hematological parameters such as red blood cell (RBC), white blood cell (WBC), haemoglobin (Hb), and haematocrit (HCT). These values, however, decreased when the dietary Zn level was further increased. The serum alkaline phosphatase level was the highest in fish fed a diet containing 30 mg kg-1 of Zn. Regression analyses based on weight gain, specific growth rate, and bone and muscle Zn concentrations indicated that the optimum dietary Zn requirement for stinging catfish was in a range of 27.4–36.5 mg kg−1.

Effects of Dietary Zinc on Growth Performance, Digestive Enzyme Activities, Antioxidant Status, and Immune Responses of Sea Cucumber Apostichopus japonicus.

Zinc is an essential micronutrient for organisms involved in regulating various biological processes. This study evaluated the effects of dietary zinc on growth performance, digestive enzyme activities, antioxidant status, and immune responses of sea cucumber Apostichopus japonicus. Five experimental diets were formulated with graded levels of zinc (0, 20, 40, 60, and 80mg/kg, respectively), and the actual dietary zinc values were 31.4, 51.0, 68.2, 91.9, and 110.8mg/kg diet, respectively. Sea cucumbers were fed with diets for 2months. The results showed the growth performance, amylase, and trypsin activities of sea cucumber increased significantly with zinc supplementation, and the best growth performance and enzyme activities were observed at 40mg/kg zinc diet. Zinc supplementation significantly increased activities of superoxide dismutase, catalase, anti-superoxide anion, and inhibiting hydroxyl radical, while significantly reduced the malondialdehyde content. Furthermore, the higher zinc supplementation levels resulted in significantly upregulated immune-related genes of hsp90, p105, rel, and lsz, suggesting that excessive zinc caused oxidative stress. The broken-line regression analysis of specific growth rate indicated dietary zinc requirement in juvenile sea cucumber was ~ 66.3mg/kg diet. Overall, dietary zinc contributes to the growth and immune resistance of juvenile sea cucumber, and our study will provide insights into the rational use of dietary zinc in aquaculture.

Effect of Dietary Supplemental Zinc on Laying Performance, Egg Quality, and Plasma Hormone Levels of Breeding Pigeons.

This study aimed to evaluate the dietary zinc requirement of parental pigeons for better laying and reproductive performance, egg quality, sex hormones, and mineral content in eggs. A total of 160 pairs of healthy American Silver King pigeons were randomly assigned to five treatments of eight replicate cages each with four pairs of birds per cage, and fed a basal diet without zinc supplementation or the basal diet supplemented with 30, 60, 90, and 120mg of zinc/kg (ZnSO4·7H2O). The experiment lasted for 45days, including two laying cycles. Results indicated the egg production rate (P = 0.081), egg shape index (P = 0.038), egg eggshell percentage (P = 0.070), and zinc and calcium contents (P < 0.01) tended to be affected or significantly affected by zinc addition. They increased quadratically with dietary zinc levels (P < 0.05). Besides, shell thickness (P = 0.069), plasma testosterone (P = 0.008), LH, and carbonic anhydrase contents (P < 0.05) tended to be affected or significantly affected by zinc addition. They increased linearly as dietary zinc level increased (P < 0.05). Compared with the control, 60mg/kg zinc addition increased egg production rate, egg shape index, zinc and calcium contents in eggshell, and plasma testosterone concentration in pigeons (P < 0.05), and tended to increase the eggshell percentage (P = 0.07). Besides, supplemental 120mg/kg zinc had higher shell thickness and LH content than control (P < 0.05), but had no difference with 60mg/kg zinc addition. In conclusion, the supplementation of zinc at the level of 60mg/kg to basal diet improved laying performance by increasing eggshell quality and sex hormone levels of breeding pigeons.

Impacts of dietary zinc on growth performance, haematological indicators, transaminase activity and tissue trace mineral contents of soft‐shelled turtle ( Pelodiscus sinensis )

A 12-week growth trial was conducted to investigate the impacts of dietary zinc on growth performance, whole-body composition, haematological parameters, liver aspartate aminotransferase and alanine transaminase activity and tissue trace mineral contents of soft-shelled turtle (Pelodiscus sinensis). Approximately 4 g of turtles were fed fishmeal-based diets with 35.43, 46.23, 55.38, 66.74, 75.06 and 85.24 mg Zn/kg. Respiratory burst, red blood cells and intestine somatic index enhanced with escalating dietary Zn concentrations up to 55.38 mg/kg and then kept constant beyond this level. Escalating dietary Zn inclusion up to 66.74 mg/kg improved weight gain, survival rate, feed intake, albumin, haemoglobin, liver aspartate aminotransferase and alanine transaminase activity, carapace ratio and crude protein of turtles, beyond which they decreased. Osmolality, hepatosomatic index and crude lipid of turtles firstly declined with elevating dietary zinc levels from 35.43 to 55.38 mg/kg diet and then increased at a higher zinc level. Liver and muscle Zn concentrations enhanced with escalating dietary zinc inclusion, whereas Cu and Fe concentrations reduced. In summary, the optimal dietary zinc requirements for turtles were 61.27, 60.46 and 60.03 mg/kg diet, based on quadratic regression analysis derived from weight gain, aspartate aminotransferase and alanine transaminase activity, respectively.

Dietary organic zinc promotes growth, immune response and antioxidant capacity by modulating zinc signaling in juvenile Pacific white shrimp (Litopenaeus vannamei)

An 8-week feeding trial was conducted to evaluate effects of dietary organic zinc (zinc amino acid chelate) on growth performance, mineral bioaccumulation in whole body, hepatopancreas and carapace, innate immune response and antioxidant capacity of juvenile Pacific white shrimp Litopenaeus vannamei. Five isonitrogenous and isolipidic diets were formulated to contain different zinc levels of 46.4 (basal diet), 65.5, 85.9, 108.4 and 130.6 mg kg−1. Dietary zinc level significantly influenced growth and feed utilization, with the lowest weight gain and highest feed conversion ratio observed in shrimp fed the basal diet. The optimal dietary zinc requirement was estimated to be 104.8 mg kg-1 for juvenile Pacific white shrimp. Shrimp fed the diet containing 130.6 mg kg−1 Zn had the highest zinc concentration in hepatopancreas and carapace, but there were no significant differences in calcium or phosphorus concentration in tissues. Dietary Zn increased the activities of lysozyme, alkaline phosphatase and polyphenol oxidase in hepatopancreas. Shrimp fed the diets supplemented with zinc had significantly higher activity of Cu/Zn SOD and lower content of malondialdehyde in hepatopancreas. The expression levels of toll, imd, lzm, proPO and alp involved in immunity and Cu/Zn sod related to oxidation resistance were up-regulated. Zinc also promoted the expression levels of mt and mtf-1, and up-regulated the expression of SLC39 family genes (zip3, zip9, zip11, zip14) in hepatopancreas. These data provided novel insights in the potential mechanism of organic zinc-induced enhancement of immunity and antioxidant capacity in Pacific white shrimp.

Estimation of dietary zinc requirement for laying duck breeders: effects on productive and reproductive performance, egg quality, tibial characteristics, plasma biochemical and antioxidant indices, and zinc deposition

This study evaluated the effects of different dietary zinc (Zn) levels on productive and reproductive performance, egg quality, tibial characteristics, plasma biochemical and antioxidant indices, and zinc deposition in laying duck breeders. A total of 504 Longyan duck breeders aged 21 wk were randomly allocated to 6 treatments and fed a basal diet (Zn, 27.7 mg/kg) or that basal diet supplemented with Zn (as ZnSO4·H2 O) at 10, 20, 40, 80, or 160 mg Zn per kg of feed for 20 wk. Each group had 6 replicates of 14 ducks each. Dietary Zn supplementation affected (P < 0.05) the egg production, FCR, and shell thickness of laying duck breeders from 21 to 40 wk, and there was a quadratic (P < 0.05) effect between them. Dietary Zn supplementation affected (P < 0.05) and quadratically (P < 0.001) increased the breaking strength, density, and dry defatted weight of tibias. Alkaline phosphatase, calcium, phosphorus, total superoxide dismutase, glutathione peroxidase (GSH-Px), and malondialdehyde (MDA) activities or content in plasma were affected (P < 0.05), and quadratically (P < 0.01) changed by dietary Zn levels. Dietary Zn supplementation affected (P < 0.01) and increased the Zn deposition in egg yolk (linear, P < 0.05; quadratic, P < 0.001) and tibia (linear, P < 0.05). The dietary Zn requirements, in mg/kg for a basal diet containing 27.7 mg/kg Zn, for Longyan duck breeders from 21 to 40 wk of age were estimated to be 65.4 for optimizing egg production, 68.6 for FCR, 102 for hatchling BW, 94.7 for eggshell thickness, 77.2 for tibial breaking strength, 81.4 for tibial density, 78.9 for tibial dry defatted weight, 69.5 for plasma GSH-Px activity, 72.4 for plasma MDA content, and 94.6 for Zn content in tibia. Overall, dietary Zn supplementation, up to 160 mg/kg feed, affected the productive performance, eggshell thickness, tibial characteristics, plasma antioxidant status, and Zn deposition of layer duck breeders. Supplementing this basal diet (27.7 mg/kg Zn) with 70 to 80 mg/kg additional Zn was adequate for laying duck breeders during the laying period.

Optimization of Dietary Zinc Requirement for Broiler Breeder Hens of Chinese Yellow-Feathered Chicken.

Simple SummaryChina is the second-largest global producer of chicken meat, almost half of which is from the Chinese yellow-feathered breed; a systematic program has been initiated to improve its feeding standards. This study evaluated the optimal requirement of dietary zinc for maximal egg production, egg quality, tibial quality, and antioxidant indices of laying broiler breeders. The results revealed several beneficial effects of supplementary zinc on egg production, feed conversion ratio, yolk zinc content, tibial quality and the antioxidant indices in the serum, liver and ovary. The optimal zinc requirement was estimated based on a regression model.This study aimed to establish the optimal dietary zinc requirement of Chinese yellow-feathered Lingnan broiler breeders. A total of 576 breeder hens aged 58 weeks were randomly assigned to six treatments, each with 6 replicates of 16 birds (n = 96/treatment). The hens were fed either a basal diet (22.81 mg/kg Zn) or the same basal diet supplemented with additional 24, 48, 72, 96, and 120 mg Zn/kg up to 65 weeks of age. Compared to the results of birds fed the basal diet (22.81 mg Zn/kg), the dietary supplementation with additional Zn (mg/kg) showed higher egg laying rate (at 48–120 mg), EM (at 96 mg/kg), yolk Zn content (at 24–120 mg/kg), fertility (at 48–120 mg/kg), hatchability (at 48–96 mg/kg), tibial breaking strength (at 24–48 mg/kg), tibial ash content (at 48 mg/kg), serum CuZnSOD activity (at 72 mg/kg) and T-AOC (at 48 mg/kg), and ovarian CuZnSOD and GSH-Px activities (at 96–120 mg/kg), and lower FCR (at 96 mg/kg). The regression model showed that the optimal supplemental Zn for maximal egg laying rate, yolk Zn content, fertility, and hatchability of Chinese yellow-feathered broiler breeders aged 58 to 65 weeks were 71.09, 92.34, 94.44 and 98.65 mg/kg diet, respectively.

Dietary zinc requirement of fingerling Indian major carp, Labeo rohita (Hamilton)

The current investigation was carried out to estimate the requirement of dietary zinc for fingerling Labeo rohita (6.3 ± 0.09 cm; 2.12 ± 0.08 g) by feeding casein-gelatin based seven isonitrogenous (350 g kg−1 crude protein) and isoenergetic (16.7 kJ g−1 gross energy) diets with incremental levels of zinc (9.52, 19.73, 29.84, 51.42, 71.91, 93.14 and 112.32 mg kg−1 diet). The experimental diets were hand-fed to triplicate group of fish at 08:00, 12:00 and 16:00 h to apparent satiety for 8-week. Significant improvement (P < .05) in live weight gain (LWG), specific growth rate, protein efficiency ratio, protein gain and feed conversion ratio were evident in fish fed incremental zinc levels up to 51.42 mg kg−1 (Zn4). No significant differences in the body protein and moisture contents were noted. However, body fat content decreased and ash content increased significantly with increment in zinc levels up to 51.42 mg kg−1 diet (Zn4). Zinc concentration in the whole body, liver, scales, vertebrae and serum significantly enhanced (P < .05) with increment in zinc levels up to 51.42 mg kg−1 diet and then levelled off. Fish fed basal diet (Zn1) containing 9.52 mg kg−1 dietary zinc exhibited significantly highest apparent zinc retention compared with other dietary treatment groups. The magnesium and iron contents in the whole body, liver, scales and vertebrae were significantly affected by the increasing levels of dietary zinc, but no change (P > .05) was noted in calcium and phosphorus concentrations. Haematological parameters such as haematocrit, haemoglobin, red blood cell counts, mean cell volume and mean cell haemoglobin were significantly affected (P < .05) excepting the mean cell haemoglobin concentration. Serum superoxide dismutase, glutathione peroxidase, catalase and alkaline phosphatase (ALP) activities responded positively (P < .05), while malondialdehyde concentration responded negatively up to 51.42 mg kg−1 dietary zinc level. Broken-line regression analysis of LWG, whole body, scales, vertebrae and serum zinc content, and ALP activity against dietary zinc concentrations indicated the break points at 50.90, 51.23, 49.19, 48.52, 52.93 and 47.85 mg kg−1 diet, respectively. Based on the above results of this investigation, inclusion of dietary zinc in the range of 47.85–52.93 mg kg−1 is recommended for L. rohita fingerlings for maintaining optimal growth, haematological parameters, tissue zinc concentration and antioxidant status.

Dietary zinc requirement of Labeo rohita juveniles fed practical diets

ABSTRACT The present study was designed to estimate the zinc (Zn) requirement of Labeo rohita juveniles fed practical diet. Treatments used for the study were consisted of six experimental diets supplemented with graded levels of Zn (0, 21, 42, 63, 84 and 104 mg/kg diet) from Zn gluconate. For each experimental diet, two replicates were allocated, and 18 fish were stocked in each replicate. The feeding trial was lasted for 90 days. Results showed that final weight, absolute weight gain, weight gain% and specific growth rate increased with increasing dietary Zn levels up to 42 mg/kg and started to decrease with further increase in dietary Zn level. Quadratic regression analysis of weight gain% data indicated that L. rohita juveniles required 62.58 mg/kg Zn for normal growth. Maximum Zn absorption was observed in fish fed diet supplemented with 42 mg/kg Zn compared with other dietary treatments. Alkaline Phosphatase (ALP) activity in kidney and spleen of L. rohita juveniles increased with the increase in dietary Zn levels up to 42 and 63 mg/kg, respectively. Conclusively, supplementation of graded levels of dietary Zn-gluconate improved the growth performance and increased the Zn bioavailability and ALP activity up to a certain limit in L. rohita juveniles.

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.

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.

Investigations on zinc bioavailability of different sources and dietary zinc requirement in juvenile grouperEpinephelus coioides

An experiment was implemented to study the effect of dietary zinc levels from three zinc sources on growth performance, immunity, and tissue mineral elements deposition on juvenile grouper. Based on the zinc free feeds, dietary zinc levels of 0, 10, 20, 40, 80, and 160 mg/kg were added from zinc sulphate (ZnSO4), tetrabasic zinc chloride (TBZC), and 2-hydroxy-4-(methylthio) butyrate zinc (Zn-HMB). The results of the 8-week study indicated that the weight gain rate (WGR) and specific growth rate (SGR) at level 10 mg/kg were significantly higher than the control fed and the reached a plateau until level 80 mg/kg, when the sources were ZnSO4 and Zn-HMB. WGR and SGR decreased significantly at level 160 mg/kg compared to 80 mg/kg in group TBZC. Feed coefficient (FCR) of all zinc source groups showed trend of decrease before rising. The alkaline phosphatase (AKP) in serum, catalase (CAT), total superoxide dismutase (SOD), copper-zinc superoxide dismutase (Cu-Zn SOD) in liver and zinc concentrations in whole body and vertebrae increased significantly than those in control group and then kept steadily in all treatments. Regardless of the sources, the manganic content of whole body or vertebra showed a downtrend. Based on the WGR, the dietary zinc requirements in juvenile grouper were 52.94 mg/kg from ZnSO4. The average relative bioavailability (RBV) of TBZC and Zn-HMB was 169.33% and 200.33%, respectively, compared to ZnSO4.

Lower Serum Zinc Concentration Despite Higher Dietary Zinc Intake in Athletes: A Systematic Review and Meta-analysis.

Zinc is an essential trace element that has been implicated in numerous biological functions, including immunity, energy metabolism and antioxidative processes. Recent evaluations of the literature have provided evidence of significant acute changes in zinc metabolism following a bout of aerobic exercise. The aim of this study was to determine the zinc status of trained athletes compared with control populations, as described in cross-sectional studies. We conducted a systematic literature search of the PubMed, Scopus, SPORTDiscus and Cochrane Library electronic databases from inception to 28 January 2016 to identify cross-sectional studies that determined the zinc status of athletes compared with a control population. Meta-analysis of the differences in serum zinc concentration and dietary zinc intake between groups were conducted. Twelve studies were included in the systematic review. Of the included studies, nine and eight studies provided sufficient data for the meta-analysis of serum zinc concentration and dietary zinc intake, respectively. Serum zinc concentration was significantly lower in athletes [-0.93μmol/L, 95% confidence interval (CI) -1.62 to -0.23] despite significantly higher dietary zinc intake compared with the control population (2.57mg/day, 95% CI 0.97-4.16). Data on erythrocyte and urinary zinc from the included studies were insufficient for meta-analysis. Despite higher total dietary zinc intake, athletes generally have lower serum zinc concentration, which suggests that athletes have higher requirement of zinc than those who are physically inactive. Further investigations of zinc metabolism during exercise and dietary zinc requirement in active populations are needed to establish evidence-based recommendations.

Upregulation of Zinc Absorption Matches Increases in Physiologic Requirements for Zinc in Women Consuming High- or Moderate-Phytate Diets during Late Pregnancy and Early Lactation

Background: Estimated physiologic requirements (PRs) for zinc increase in late pregnancy and early lactation, but the effect on dietary zinc requirements is uncertain.Objective: The aim of this study was to determine changes in daily fractional absorbed zinc and total absorbed zinc (TAZ) from ad libitum diets of differing phytate contents in relation to physiologic zinc requirements during pregnancy and lactation.Methods: This was a prospective observational study of zinc absorption at 8 (phase 1) and 34 (phase 2) wk of gestation and 2 (phase 3) and 6 (phase 4) mo of lactation. Participants were indigenous Guatemalan women of childbearing age whose major food staple was maize and who had been randomly assigned in a larger study to either of 2 ad libitum feeding groups: low-phytate maize (LP; 1.6 mg/g; n = 14) or control maize (C; 7.1 mg/g; n = 8). Total dietary zinc (milligrams per day, TDZ) and phytate (milligrams per day) were determined from duplicate diets and fractional absorption (FAZ) by dual isotope ratio technique (TAZ = TDZ × FAZ). All variables were examined longitudinally and by group and compared with PRs. TAZ values at later phases were compared with phase 1. Measured TAZ was compared with predicted TAZ for nonpregnant, nonlactating (NPNL) women.Results: TAZ was greater in the LP group than in the C group at all phases. All variables increased from phase 1 to phases 2 and 3 and declined at phase 4. TAZ increased by 1.25 mg/d (P = 0.045) in the C group and by 0.81 mg/d (P = 0.058) in the LP group at phase 2. At phase 3, the increases were 2.66 mg/d (P = 0.002) in the C group and 2.28 mg/d (P = 0.0004) in the LP group, compared with a 1.37-mg/d increase in PR. Measured TAZ was greater than predicted values in phases 2-4.Conclusions: Upregulation of zinc absorption in late pregnancy and early lactation matches increases in PRs of pregnant and lactating women, regardless of dietary phytate, which has implications for dietary zinc requirements of pregnant and lactating women.

Genetic Variations as Modifying Factors to Dietary Zinc Requirements-A Systematic Review.

Due to reduced cost and accessibility, the use of genetic testing has appealed to health professionals for personalising nutrition advice. However, translation of the evidence linking polymorphisms, dietary requirements, and pathology risk proves to be challenging for nutrition and dietetic practitioners. Zinc status and polymorphisms of genes coding for zinc-transporters have been associated with chronic diseases. The present study aimed to systematically review the literature to assess whether recommendations for zinc intake could be made according to genotype. Eighteen studies investigating 31 Single Nucleotide Polymorphisms (SNPs) in relation to zinc intake and/or status were identified. Five studies examined type 2 diabetes; zinc intake was found to interact independently with two polymorphisms in the zinc-transporter gene SLC30A8 to affect glucose metabolism indicators. While the outcomes were statistically significant, the small size of the effect and lack of replication raises issues regarding translation into nutrition and dietetic practice. Two studies assessed the relationship of polymorphisms and cognitive performance; seven studies assessed the association between a range of outcomes linked to chronic conditions in aging population; two papers described the analysis of the genetic contribution in determining zinc concentration in human milk; and two papers assessed zinc concentration in plasma without linking to clinical outcomes. The data extracted confirmed a connection between genetics and zinc requirements, although the direction and magnitude of the dietary modification for carriers of specific genotypes could not be defined. This study highlights the need to summarise nutrigenetics studies to enable health professionals to translate scientific evidence into dietary recommendations.

Dietary zinc requirement of Siberian sturgeon (Acipenser baerii, Brandt 1869) juveniles, based on the growth performance and blood parameters

This study investigated the effect of dietary Zn levels on growth performance, feed utilization, and hematological parameters of juvenile Siberian sturgeon (Acipenser baerii, Brandt 1869). The five semi-purified diets were formulated by adding 0, 5, 10, 20, and 40 mg Zn kg−1 diet in the form of zinc sulfate (ZnSO4) to provide the actual dietary value of 14.7, 20.8, 27.3, 37.7, and 46.4 Zn kg−1 diet, respectively. The results showed that dietary Zn elevating level significantly improved the growth and feed utilization of the fish (p < 0.05), but not the hepatosomatic index (p > 0.05). Erythrocyte number, hemoglobin concentration, and hematocrit were increased with raising dietary Zn level (p < 0.05), whereas a regular trend was not observed in blood indices, including MCV, MCH, and MCHC. A significant increase was also found in the leucocyte number followed by their differential counts, except for eosinophil percentage. The broken line regression model indicated optimal dietary Zn level for growth maximization of fish was estimated to be 29.15 mg Zn kg−1 diet. In spite of well correlation with dietary Zn level, no break point was observed to estimate the juvenile Siberian sturgeon requirement based on the erythrocyte numbers.

A Review of Dietary Zinc Recommendations.

Large discrepancies exist among the dietary zinc recommendations set by expert groups. To describe the basis for the differences in the dietary zinc recommendations set by the World Health Organization, the US Institute of Medicine, the International Zinc Nutrition Consultative Group, and the European Food Safety Agency. We compared the sources of the data, the concepts, and methods used by the 4 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. All 4 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 fecal zinc (EFZ) 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. Estimates for the physiological and dietary requirements varied across the 4 expert groups. The European Food Safety Agency was the only expert group that set dietary zinc recommendations at 4 different levels of dietary phytate for adults (but not for children) and as of yet no tolerable upper intake level for any life-stage group.

Immediate Effects of Aerobic Exercise on Plasma/Serum Zinc Levels: A Meta-analysis.

Zinc is involved in numerous metabolic roles, including energy metabolism, immunity, and antioxidative effects. Zinc losses during exercise, in particular through sweat, are well documented. However, conflicting results have been reported for changes in circulating and tissue zinc concentration as a result of exercise. The purpose of this article is to quantify the immediate effect of aerobic exercise on plasma or serum zinc levels, in healthy participants. We conducted a systematic review of peer-reviewed articles published up to December 20, 2014, to identify studies that investigated the acute effects of exercise on selected indices of zinc status. Meta-analyses were conducted to determine the change in serum zinc concentration immediately after a bout of aerobic exercise. Forty-five studies were included in the systematic literature review. Of the included studies, sufficient data were available from 34 studies (providing 46 comparisons) to quantify the change in serum zinc concentration after exercise. Serum zinc concentration was significantly higher immediately after exercise (0.45 ± 0.12 μmol·L(-1), P < 0.001; mean ± SE). Secondary analyses showed greater increase in serum zinc for untrained individuals and exercise sessions that involved running or maximal intensity. Insufficient data were available to determine the effects of exercise on urinary, sweat, and erythrocyte zinc. The present systematic review and meta-analysis indicated significant increase in serum zinc concentration immediately after an aerobic exercise session, suggesting acute perturbations in zinc homeostasis. Further research is required to ascertain the long-term effects of exercise on zinc metabolism and potential consequences for dietary zinc requirement for physically active populations.

Effect of dietary zinc level on growth, enzyme activity and body trace elements of hybrid tilapia,Oreochromis niloticus × O. aureus, fed soya bean meal-based diets

A feeding experiment was conducted to determine the dietary zinc (Zn) requirement of hybrid tilapia fed on a diet with soya bean meal as the sole protein source. The quantity of phytic acid in the experimental diet was 15.5 g kg−1. Juvenile hybrid tilapia were fed on diets containing 31–227 mg Zn kg−1 in triplicates for 6 weeks. Haematology of the fish was not affected by various dietary Zn levels. Fish fed on a diet containing 31 mg kg−1 endogenous Zn showed the lowest growth rates, feed utilization, and body and plasma Zn levels. Weight gain (WG), plasma Zn level and superoxide dismutase (SOD) activity increased when a higher quantity of dietary Zn of 127 mg kg−1 was administered to the experimental fish. Beyond this level, the values of these parameters were relatively stable. On the other hand, within the dietary Zn range tested, whole-body Zn and ash increased with higher dietary Zn levels. Analysis using a broken-line model showed that the dietary Zn requirements of hybrid tilapia fed on soya bean meal-based diets containing 15.5 g kg−1 endogenous phytic acid were 115, 115 and 105 mg kg−1 based on WG, whole-body Zn retention and plasma Zn level, respectively.

Contribution of leafy vegetable sauces to dietary iron, zinc, vitamin A and energy requirements in children and their mothers in Burkina Faso.

Improved leafy vegetable (LV) sauces, with amaranth, sorrel, and Ceylon spinach/spider plant leaves were formulated from traditional recipes to assess their potential use for food-to-food fortification in iron, zinc and vitamin A in the diet of young children and their mothers in Burkina Faso. Improvement was based on an increase in LV proportion and a decrease in mineral absorption inhibitors. An increase in iron content of up to 3 mg/100 g was obtained in some improved sauces in which dried fish was replaced by chicken liver, and vitamin A content was about 40 times higher than in traditional sauces. Fractional dialyzable iron was low in all sauces. Intakes of sauce were measured to assess their acceptability and no significant difference was found between traditional and improved formulations. The mean intakes of sauces were 66 ± 40 g for young children and 166 ± 65 g for their mothers. Amaranth or Ceylon spinach/spider plant sauces, consumed with the cereal based paste "tô" twice a day, would contribute 80 to 86% of children's estimated average requirement (EAR) of iron and to 90 to 170% of EAR of vitamin A but their contribution to zinc and energy needs would remain low.