Zinc status relates to hematological deficits in middle-aged women

Relationship between Plasma Zinc and Red Blood Cell Zinc Levels in Hospitalized Patients

Background

Patient zinc stores are quantified with plasma or red blood cell (RBC) measures. The relationship between these 2 measures of zinc status has not been determined in a broad population of hospitalized patients.

Methods

Both plasma zinc and RBC zinc were prospectively collected and measured in 252 consenting patients admitted urgently to hospital. Plasma and RBC zinc levels were measured within 48 h of admission. We collected demographic, vitals, and laboratory data for use in multivariate regression models that included markers of acute disease severity and systemic inflammation.

Results

Plasma zinc and RBC zinc levels were low in 63% and 10% of hospitalized patients, respectively. Categorized zinc levels based on normal intervals for plasma and RBC zinc values were not related (χ2 0.47 [2 df] P = 0.79). The Pearson correlation coefficient between plasma zinc and RBC zinc was −0.09 (P = 0.15). After adjustments for multiple clinical covariates, the correlation coefficient remained insignificant (r = −0.11, P = 0.08). Plasma zinc was inversely associated with markers of inflammation including the neutrophil-to-lymphocyte ratio and temperature.

Conclusions

Patient-specific plasma and RBC zinc are unrelated in hospitalized patients, possibly due to decreased values with acute illness seen in the former but not the latter. Future studies are required to determine which of these measures best predicts outcomes in hospitalized patients.

Zinc mediates the interaction between ceruloplasmin and apo-transferrin for the efficient transfer of Fe(III) ions

Fe(II) exported from cells is oxidized to Fe(III), possibly by a multi-copper ferroxidase (MCF) such as ceruloplasmin (CP), to efficiently bind with the plasma iron transport protein transferrin (TF). As unbound Fe(III) is highly insoluble and reactive, its release into the blood during the transfer from MCF to TF must be prevented. A likely mechanism for preventing the release of unbound Fe(III) is via direct interaction between MCF and TF; however, the occurrence of this phenomenon remains controversial. This study aimed to reveal the interaction between these proteins, possibly mediated by zinc. Using spectrophotometric, isothermal titration calorimetric, and surface plasmon resonance methods, we found that Zn(II)-bound CP bound to iron-free TF (apo-TF) with a Kd of 4.2 μM and a stoichiometry CP:TF of ∼2:1. Computational modeling of the complex between CP and apo-TF predicted that each of the three Zn(II) ions that bind to CP further binds to acidic amino acid residues of apo-TF to play a role as a cross-linker connecting both proteins. Domain 4 of one CP molecule and domain 6 of the other CP molecule fit tightly into the clefts in the N- and C-lobes of apo-TF, respectively. Upon the binding of two Fe(III) ions to apo-TF, the resulting diferric TF [Fe(III)2TF] dissociated from CP by conformational changes in TF. In human blood plasma, zinc deficiency reduced the production of Fe(III)2TF and concomitantly increased the production of non-TF-bound iron. Our findings suggest that zinc may be involved in the transfer of iron between CP and TF.

Zinc Supplementation Stimulates Red Blood Cell Formation in Rats

In rats, mice, and humans, it is known that zinc deficiency may be related to anemia, and zinc supplementation influences hemoglobin production. Our previous studies indicate that in fish, zinc supplementation stimulates red blood cell (RBC) formation (erythropoiesis). However, it is not clear whether the mechanism of zinc-induced erythropoiesis stimulation in fish also occurs in rats. We induced anemia in rats using phenylhydrazine (PHZ) and injected either saline or ZnSO₄ solution. We found that an appropriate amount of zinc stimulated erythropoiesis in the PHZ-induced anemic rats. The effects of ZnSO₄ injection were dose-dependent. When the concentration of ZnSO₄ was higher than 2.8 mg zinc/kg body weight, the RBC level of the anemic rats increased from 60 ± 7% to 88 ± 10% that of the normal rats in two days. Rat bone marrow cells with or without ZnCl₂ supplementation were cultured in suspension in vitro. In the cell culture when the zinc concentration was at 0.3 mM, a 1.6-fold proliferation of nascent immature reticulocytes (new RBCs) was observed after one day. In the rat blood, zinc was combined with serum transferrin to induce erythropoiesis. The stimulation of RBC formation by zinc appears to be common among different animals.

Zinc deficiency and its predictive capacity for anemia: Unique model in school children

BACKGROUND

Zinc deficiency is thought to be common in children, but its predictive capacity for anemia is unclear. Thus, this study identified zinc deficiency in school children, and investigated the association between zinc status and hemoglobin, together with other estimates of anemia.

METHODS

For this case-control study, 349 of 483 children between 6.5 and 14.8 years old were included from primary schools in Bolu, Turkey. We measured weight, length, body mass index, and complete blood count with serum zinc, ferritin, vitamin B12 and folate. We investigated the differences between the groups and the effects of independent predictors such as age, gender, ferritin, zinc, vitamin B12 and folate on hemoglobin, on hierarchical multiple regression analysis.

RESULTS

Thirty-eight (10.9%) of 349 children had low serum zinc concentration, and 21 (6.0%) were anemic. There were 12 anemic children in the zinc-deficient group and nine in the zinc-sufficient control group (31.5% vs 2.9%) with similar ferritin levels. On regression analysis, zinc had the strongest association with hemoglobin. On receiver operating characteristic analysis, the cut-off for serum zinc for prediction of anemia was 71.5 μg/dL.

CONCLUSIONS

The strongest association of zinc with hemoglobin suggests that low zinc contributed the most to the observed anemia in children.

The influence of food consumption and socio-economic factors on the relationship between zinc and iron intake and status in a healthy population

OBJECTIVE

To examine Zn and Fe nutritional status of a healthy population by means of anthropometric, dietary and biochemical measurements and to investigate the relationship of usual Zn and Fe dietary intakes to Zn and Fe status. In addition, to examine the impact of food choices and socio-economic factors on Fe and Zn dietary intakes and status with the aim to identify groups at risk of dietary deficiency and suggest factors that may influence the status of these nutrients.

DESIGN

Food consumption was assessed by 24 h recall questionnaires. Twenty biochemical parameters were measured, of which Hb, haematocrit, erythrocyte count and plasma concentrations of Fe and Zn were directly related to Fe and Zn nutrition. The prevalence of study participants with inadequate micronutrient intakes was calculated using the Estimated Average Requirement cut-point method.

SETTING

Serbia, Europe.

SUBJECTS

Apparently healthy adults (25-65 years of age).

RESULTS

Mean daily Zn and Fe intakes were 9·1 mg and 11·6 mg for males and 7·3 mg and 9·4 mg for females, respectively. Five per cent of the study population had inadequate dietary Fe intake and 15-25 % had inadequate Zn intake. Lower Hb concentrations were measured in women with lower Zn intakes. No differences in Fe and Zn intakes and status among various socio-economic groups were observed, except for Fe intake between the low-income and affluent groups.

CONCLUSIONS

Regular follow-ups are needed to ensure that potential deficiencies of Zn and Fe do get recognized and addressed in a timely manner.

Determination of trace elements in Ethiopian, Vietnamese, and Japanese women using high-resolution IC-PMS

OBJECTIVES

Humans and other living organisms require small quantities of trace elements throughout life. Both insufficient and excessive intakes of trace elements can have negative consequences. However, there is little information on serum level of trace elements in different populations. This study examines serum levels of trace elements in Ethiopian, Japanese, and Vietnamese women.

METHODS

Random samples of healthy women who were referred for routine hospital laboratory examinations in the cities of Hanoi, Sapporo, and Gondar were invited to participate in the study. Serum levels of magnesium, zinc, copper, iron, selenium, and calcium were determined using an inductively coupled plasma mass spectrometer. Furthermore, body mass index of each study participant was determined.

RESULTS

The mean ± SD serum concentrations of zinc (μg/dL), copper (μg/dL), iron (μg/dL), selenium (μg/dL) and calcium (mg/dL), respectively, were 76.51 ± 39.16, 152.20 ± 55.37, 385.68 ± 217.95, 9.15 ± 4.21, and 14.18 ± 3.91 in Ethiopian women; 111.49 ± 52.92, 105.86 ± 26.02, 155.09 ± 94.83, 14.11 ± 3.41, and 11.66 ± 2.51 in Vietnamese women; and 60.69 ± 9.76, 107 ± 156, 268 ± 128, 8.33 ± 3.65, and 11.18 ± 0.68 in Japanese participants. Ethiopian women had significantly higher level of serum calcium than Vietnamese and Japanese women (both P < 0.05). Although the mean calcium concentration in Vietnamese women was higher than in women from Japan, the difference was not statistically significant (P > 0.05). Furthermore, compared with Japanese women, Ethiopian women had significantly high iron and copper concentrations (P < 0.05). Serum selenium and zinc levels were higher in Vietnamese than Ethiopian women.

CONCLUSION

The study revealed a remarkable difference in serum concentrations of trace elements in women from different countries, implying differences in trace elements in the food or soil.

Effect of short term zinc supplementation on iron status of children with acute diarrhea

OBJECTIVE

To study the effect of short term (2 wk) zinc supplementation on hemoglobin and iron status of children with acute diarrhea.

METHODS

This study was a prospective, open label, single arm interventional trial conducted from June 2008 through October 2009 in a teaching hospital of North India. Three to sixty months old children presenting with acute diarrhea participated in the study. Subjects were supplemented with recommended doses of oral zinc gluconate for 2 wk. Changes in levels of hemoglobin, serum iron, total iron binding capacity, and serum ferritin were the main outcome measures.

RESULTS

Sixty-two patients completed the study successfully. The prevalence of anemia before and after 2 wk of zinc supplementation remained unchanged. However, a small decline (p > 0.05) was observed in mean hemoglobin (from 8.95 ± 1.4 to 8.73 ± 1.43 g/dL), serum iron (79.56 ± 45.81 to 78.61 ± 44.41 μg/dL) and ferritin (84.77 ± 45.35 to 83.55 ± 44.10 ng/mL) levels. Total iron binding capacity increased from 331.60 ± 109.72 to 341.30 ± 119.90 μg/dL post supplementation (p > 0.05).

CONCLUSIONS

Even though statistically insignificant, the small change observed in the levels of hemoglobin, and indicators of iron status following short term zinc supplementation might assume significance in some settings in developing countries where children receive short courses of zinc repeatedly for frequent diarrheal episodes.

Evaluating environmental and social influences on iron and zinc status of pregnant subsistence farmers in two geographically contrasting regions of Southern Malawi

Micronutrient deficiency affects over 4.5 billion people worldwide, the majority in developing countries. Deficiencies of iron (and associated anaemia) and zinc in pregnancy are associated with complications, maternal and neonatal mortality, and developmental disorders in the foetus and growing child. We report the results of pilot study which used an interdisciplinary approach to explore environmental and sociocultural factors influencing the micronutrient status in the soil-plant-human transfer for pregnant subsistence farmers in two geographically contrasting regions of Southern Malawi. It evaluated micronutrient status in soil and the staple crop and explored the context for their transfer to pregnant women. Scientific and social science methods were used to collect data, following full sensitisation of the communities. A total of 99 participants were recruited from Chiradzulu (plateau) and Chikwawa (floodplain). Soil, maize and blood samples were collected, along with food frequency and health behaviour questionnaires and anthropological observation. Statistical analysis revealed that soil iron was significantly higher in Chiradzulu than in Chikwawa; total iron concentration is not deemed to be deficient in either area. Soil zinc was not significantly different between areas. Maize concentrations of iron and zinc were not significantly different between areas, and were not deficient relative to improved cultivars. Blood iron deficiency and associated anaemia were problematic in both areas, but more so in Chikwawa than in Chiradzulu, and zinc deficiency was similar in both areas. The study has identified a significant difference in the blood iron status of the participants of the two communities, and has shown that this difference is not accounted for by the staple crop maize. Socio-geographical factors appear to play a significant role in the micronutrient health of the populations. The findings lend support to multifaceted community intervention studies which educate communities on strategies to tackle micronutrient deficiencies.

Acute inhibition of iron bioavailability by zinc: studies in humans

Iron (Fe) and zinc (Zn) deficiencies constitute two of the most important nutritional and public health problems affecting developing countries. Combined supplementation or fortification with Zn and Fe are strategies that can be used to improve the Zn and Fe status of a population. However, there is concern about potential negative interactions between these two micronutrients due to a competitive binding to DMT1 and Zip14 transporter. Studies performed in humans have shown an inhibitory effect of Zn on Fe absorption when both minerals are given together as a solution in fasting conditions. We found that at low doses of iron (0.5 mg) the threshold for the inhibition of iron bioavailability was at a Zn:Fe wt/wt ratio ≥5.9:1, whereas at higher doses of Fe (10 mg) this inhibition occurred at 1:1 Zn:Fe wt/wt ratio. This differential response could be explained by the variation in the abundance of both cations as they compete for a limited number of shared transporters at the enterocyte. Conflicting results have been obtained when this interaction was studied in different food matrices. A negative interaction was not observed when Fe and Zn were provided in a composite hamburger meal, premature formula, human milk, or cow milk. A decrease on Fe absorption was observed in only 1 of 3 studies when Fe and Zn were supplied in wheat flour. The possibility of a negative interaction should be considered for supplementation or fortification programs with both microminerals.

Renal zinc clearance/glomerular filtration rate ratio as an indicator of marginal zinc deficiency associated with iron deficiency in childhood

OBJECTIVE

To evaluate the usefulness of renal zinc clearance/glomerular filtration rate ratio (R(ClZn)/GFR) as an indicator of marginal zinc deficiency that is generally associated with iron deficiency in childhood.

METHODS

Zinc status was evaluated in 36 iron-deficient children (22 boys and 14 girls) who ranged in age from 1 to 10 years using serum zinc concentration and U(Zn/Cr) and R(ClZn)/GFR ratios. The results were compared with the zinc status of 36 similar-aged healthy children (24 boys and 12 girls).

RESULTS

Serum zinc concentrations were 96.72 +/- 2.13 microg/dL and 93.93 +/- 1.95 microg/dL in iron-deficient and healthy subjects, respectively (p > 0.05). U(Zn/Cr) ratios were 0.54 +/- 0.04 microg/mg and 0.88 +/- 0.04 microg/mg (p < 0.0001); R(ClZn)/GFR ratios were 2.27 x 10(-3) +/- 0.20 and 3.32 x 10(-3) +/- 0.20 (p < 0.001) in iron-deficient and healthy subjects, respectively. Individual values of R(ClZn)/GFR and U(Zn/Cr) ratios correlated with hemoglobin (Hb) concentrations (r = 0.34, p < 0.01 and r = 0.26, p < 0.05). Data grouped according to the ranges of Hb concentrations and R(ClZn)/GFR and U(Zn/Cr) ratios fit the following equations: The statistically significant difference in U(Zn/Cr) and R(ClZn)/GFR ratios between groups indicates decreased urinary estimation of marginal zinc deficiency, whereas no change was observed in serum zinc concentrations. According to the regression equation, it can be postulated that the R(ClZn)/GFR ratio is a linear function of Hb concentration and the U(Zn/Cr) ratio.

CONCLUSION

R(ClZn)/GFR ratio was a reliable indicator for reduction in urinary zinc excretion; it estimated the marginal zinc deficiency associated with iron deficiency. The R(ClZn)/GFR ratio can be calculated using one sample of blood and urine; thus it could serve as an alternative indicator of marginal zinc deficiency, especially in routine health care.

Zinc transporters ZnT1 (Slc30a1), Zip8 (Slc39a8), and Zip10 (Slc39a10) in mouse red blood cells are differentially regulated during erythroid development and by dietary zinc deficiency

Zinc is essential for normal erythroid cell functions and therefore intracellular zinc homeostasis during erythroid differentiation is tightly regulated. However, a characterization of zinc transporters in erythrocytes has not been conducted. The membrane fraction of mature mouse RBC was screened for zinc transporter expression using western analysis as a first step in the characterization process. ZnT1, Zip8, and Zip10 were detected among the 12 transporter proteins tested. We examined expression of these zinc transporters during erythropoietin (EPO)-induced differentiation of splenic erythroid progenitor cells into reticulocytes. Both Zip8 and Zip10 mRNA increased by 2-6 h after addition of EPO to the cells. In contrast, maximal RNA levels for the zinc transporter ZnT1 and erythroid delta-aminolevulinic acid synthase were only produced by 24 h after EPO. We confirmed these changes in transcript abundance by western analysis. Dietary zinc status influences zinc-dependent functions of RBC. To determine whether the identified zinc transporters respond to dietary zinc status, mice were fed a zinc-deficient or control diet. Incorporation of (65)Zn into erythrocytes in vitro was significantly increased in cells from the zinc-deficient mice. Western analysis and densitometry revealed that erythrocyte Zip10 was upregulated and ZnT1 was downregulated in the zinc-depleted mice. Zip8 was not affected by restricted zinc intake. Collectively, these data suggest that the zinc transporters ZnT1, Zip8, and Zip10 are important for zinc homeostasis in erythrocytes and that ZnT1 and Zip10 respond to the dietary zinc supply.

Psychosocial and biochemical interactions in aging: preliminary results from an Italian old sample of "Zincage" project

The study of the interactions among biological factors and psychosocial conditions is a very innovative field, because data are lacking in the scientific literature. Among biological aspects, zinc is an essential element in the elderly, especially in relation to one of the proteins, such as albumin, involved in zinc transport into the cells. In this study, the aim is the assessment of the interrelationship between albumin value (used as an index of the body zinc status) and some psychosocial dimensions in elderly Italian sample recruited for ZINCAGE project, supported by the European Commission in the "Sixth Framework Programme". Some tests and questionnaires were administered to older people included in the trial: the "life-style questionnaire"; the mini mental state examination (MMSE); the geriatric depression scale (GDS-15 items). On the basis of the Senieur Protocol for gerontological studies, a sample of 291 Italian healthy old subjects has been recruited in Central Italy and divided into 3 age groups: (a) 125 subjects aged from 65 to 74 years, (b) 89 subjects aged from 75 to 84 years, (c) 77 subjects aged >or=85 years (classified like successful old people). No cognitive impairment assessed by MMSE was observed in 67.5% of the sample; 64.0% had GDS score less than 5, indicating no depression, whereas the prevalence of biological albumin deficiency (<3.5 g/dl) found in Italian old people was 21.0%. Sixty one percent of subjects with albumin deficiency displayed higher values of GDS (>or=5). These preliminary results showed an interrelationship among serum albumin value and psychosocial aspects in Italian old population, suggesting that low albumin values may be involved in impaired psychological dimensions.

Effects of separate delivery of zinc or zinc and vitamin A on hemoglobin response, growth, and diarrhea in young Peruvian children receiving iron therapy for anemia

INTRODUCTION

Anemia is the most prevalent nutritional deficiency in the world. Attempts to improve iron indexes are affected by deficiency of and interaction between other micronutrients.

OBJECTIVE

Our goal was to assess whether zinc added to iron treatment alone or with vitamin A improves iron indexes and affects diarrheal episodes.

DESIGN

This was a randomized, placebo-controlled, double-blind trial conducted in Peru. Anemic children aged 6-35 mo were assigned to 3 treatment groups: ferrous sulfate (FS; n = 104), ferrous sulfate and zinc sulfate (FSZn; n = 109), and ferrous sulfate, zinc sulfate, and vitamin A (FSZnA; n = 110). Vitamin A or its placebo was supplied only once; iron and zinc were provided under supervision >/=1 h apart 6 d/wk for 18 wk.

RESULTS

The prevalence of anemia was 42.97%. The increase in hemoglobin in the FS group (19.5 g/L) was significantly less than that in the other 2 groups (24.0 and 23.8 g/L in the FSZn and FSZnA groups, respectively). The increase in serum ferritin in the FS group (24.5 mug/L) was significantly less than that in the other 2 groups (33.0 and 30.8 mug/L in the FSZn and FSZnA groups, respectively). The median duration of diarrhea and the mean number of stools per day was significantly higher in the FS group than in other 2 groups (P < 0.005).

CONCLUSION

Adding zinc to iron treatment increases hemoglobin response, improves iron indexes, and has positive effects on diarrhea. No additional effect of vitamin A was found.

Zinc and IGF-I concentrations in pregnant women with anemia before and after supplementation with iron and/or zinc

OBJECTIVE

The objective of our study was to investigate zinc (Zn) status and effects of Zn supplementation in relation to insulin-like growth factor-I (IGF-I) and iron deficiency anemia in pregnant women. The role of Zn and IGF-I in hematologic abnormalities has remained unclear.

METHODS

Thirty-eight Japanese women, when examined at the second trimester of pregnancy, had hemoglobin concentrations below 11.0 g/dL and 32 of 38 had normocytic erythrocytes. These 38 women were divided into three groups, and we compared the hematological status and serum IGF-I levels before and after iron (Group A) or Zn (Group B) or iron plus Zn (Group C) supplementation.

RESULTS

The concentrations of hemoglobin (Hb) did not change in groups A and B. In group C, Hb levels were significantly increased from 10.3+/-0.3 to 11.0+/-0.6 g/dL. Furthermore, numbers of RBC and reticulocytes also increased significantly. Concentrations of iron, IGF-I and total iron binding capacity (TIBC) were increased, and concentrations of erythropoietin were decreased, but not statistically. There were significant positive correlations between increases in IGF-I and increases in Hb and RBC in the Zn administered groups.

CONCLUSION

Zn status to some extent can account for hematological abnormalities in pregnant women. Zn derived IGF-I has a role in the regulation of hematopoiesis in pregnant women.