Iron sources on iron status and gene expression of iron related transporters in iron-deficient piglets

Improvement of in vivo iron bioavailability using mung bean peptide-ferrous chelate

There is an increasing amount of research into the development of a third generation of iron supplementation using peptide-iron chelates. Peptides isolated from mung bean were chelated with ferrous iron (MBP-Fe) and tested as a supplement in mice suffering from iron-deficiency anemia (IDA). Mice were randomly divided into seven groups: a group fed the normal diet, the IDA model group, and IDA groups treated with inorganic iron (FeSO4), organic iron (ferrous bisglycinate, Gly-Fe), low-dose MBP-Fe(L-MBP-Fe), high-dose MBP-Fe(H-MBP-Fe), and MBP mixed with FeSO4 (MBP/Fe). The different iron supplements were fed for 28 days via intragastric administration. The results showed that MBP-Fe and MBP/Fe had ameliorative effects, restoring hemoglobin (HGB), red blood cell (RBC), hematocrit (HCT), and serum iron (SI) levels as well as total iron binding capacity (TIBC) and body weight gain of the IDA mice to normal levels. Compared to the inorganic (FeSO4) and organic (Gly-Fe) iron treatments, the spleen coefficient and damage to liver and spleen tissues were significantly lower in the H-MBP-Fe and MBP/Fe mixture groups, with reparative effects on jejunal tissue. Gene expression analysis of the iron transporters Dmt 1 (Divalent metal transporter 1), Fpn 1 (Ferroportin 1), and Dcytb (Duodenal cytochrome b) indicated that MBP promoted iron uptake. These findings suggest that mung bean peptide-ferrous chelate has potential as a peptide-based dietary supplement for treating iron deficiency.

Effects of dietary iron sources on growth performance, iron status, Fe-containing enzyme activity and gene expression related to iron homeostasis in tissues of weaned pigs

The aim of this study is to evaluate the effects of dietary iron sources on growth performance, iron status and activities of Fe-containing enzymes and gene expression related to iron homeostasis in tissues of weaned pigs. A total of 480 piglets at d 28 (Duroc X Landrace) were allotted to four groups as a factorial arrangement of treatments with 30 pigs/pen (male: female = 1:1) and 4 replicate pens/treatment. The treatments for iron in the diets were: control basal diet (Con); Con + 150 mg Fe/kg as inorganic Fe (iFe); Con + 75 mg Fe/kg as inorganic Fe + 75 mg Fe/kg as organic Fe-peptide complex (iFe+oFe) and Con + 150 mg of Fe/kg as organic Fe-peptide complex (oFe). The feeding trial lasted for 36 days. There were no significant differences in final body weight, ADG, ADFI, and G/F as well as blood hemoglobin and MCHC contents between piglets fed the control and iron-supplemented groups (P > 0.05). The iron supplemented groups exhibited increased iron content in the liver, kidney and spleen as well as the CAT and SDH activities in liver compared to the control group (P < 0.05), while piglets in oFe group experienced greater Fe accumulation and activities of CAT and SDH in the liver than piglets in the iFe group. Compared with the control group, dietary supplementation of iron increased the NCOA4 mRNA expression and decreased the TfR1 mRNA expression in liver of piglets. The TfR1, NCOA4 and Ferritin mRNA expressions of bone marrow in both iFe and iFe+oFe groups were greater than both in the Con and oFe groups. These results suggest that dietary supplementation of iron does not influence the growth performance and hematological parameters in weaned pigs fed a corn-soybean meal basal diet (75.8 mg/kg) from d 28 to d 70, but increased tissue iron status and activities of Fe-containing enzymes at d 70. The addition of organic Fe-peptide complexes presents greater beneficial effects on enhancing tissue Fe accumulation and Fe-containing enzyme activities, which may be involved in different gene expression patterns related to iron intake and transport in tissues of weaned pigs.

A comprehensive review of calcium and ferrous ions chelating peptides: Preparation, structure and transport pathways

Calcium and iron play crucial roles in human health, deficiencies of which have globally generated public health risks. The poor solubility, low bioavailability and gastrointestinal irritation of existing commercial mineral supplements limit their further application. As an emerging type of mineral supplement, mineral chelating peptides have drawn plenty of attention due to their advantages in stability, absorptivity and safety. A majority of calcium and ferrous ions chelating peptides have been isolated from food processing by-products. Enzymatic hydrolysis combined with affinity chromatography, gel filtration and other efficient separation techniques is the predominant method to obtain peptides with high calcium and ferrous affinity. Peptides with small molecular weight are more likely to chelate metals, and carboxyl, amino groups and nitrogen, oxygen, sulfur atoms in the side chain, which can provide lone-pair electrons to combine with metallic ions. Unidentate, bidentate, tridentate, bridging and α mode are regarded as common chelating modes. Moreover, the stability of peptide-mineral complexes in the gastrointestinal tract and possible transport pathways were summarized. This review is to present an overview of the latest research progress, existing problems and research prospects in the field of peptide-mineral complexes and to provide a more comprehensive theoretical basis for their exploitation in food industry.

Delivery systems for improving iron uptake in anemia

Anemia poses a threat to a broad population globally as depleted hemoglobin leads to a plethora of conditions, and the most common cause includes iron deficiency. Iron is an essential element important for erythropoiesis, DNA synthesis, protection of the immune system, energy production, and cognitive function and hence should be maintained at appropriate levels. Various proteins are involved in transporting and absorption of iron, activation of heme synthesis, and RBC production that could be possible targets to improve iron delivery. Oral supplementation of iron either from dietary or synthetic sources has been the frontline therapy for treating iron deficiency in anemia. At the same time, intravenous administration is provided in chronic anemia, such as chronic kidney diseases (CKD). This review focuses on the strategies developed to overcome the disadvantages of available iron therapies and increase iron absorption and uptake in the body to restore iron content. Nanotechnology combined with the food fortification processes gained attention as they help develop new delivery systems to improve iron uptake by enterocytes. Furthermore, naturally obtained products such as polysaccharides, peptides, proteins, and new synthetic molecules have been used in fabrication of iron-carrier systems. The establishment of transdermal iron delivery systems such as microneedle arrays or iontophoresis, or the discovery of new molecules also proved to be an effective way for delivering iron in patients non-compliant to oral therapy.

Exploratory Study: Excessive Iron Supplementation Reduces Zinc Content in Pork without Affecting Iron and Copper

Simple Summary

Currently, all pigs raised on intensive farms develop iron-deficiency anemia if they do not receive supplemental iron at birth. Weaning diets commonly contain high concentrations of iron, and the effect on the copper and zinc contents in pork is unknown. In this exploratory work, we determined the effect of excessive oral iron supplementation on the contents of these microminerals in pork. Surprisingly, we found that high iron doses of 3000 ppm reduced the zinc content of pork by 32–55%.

Abstract

The aim of this work was to determine in an exploratory manner the effect of excessive iron supplementation on iron, zinc, and copper contents in pork and pork offal. Pigs averaging 50 days in age and 15 ± 1.3 kg body weight were allocated to a control group (500 ppm dietary Fe) and a supplemental group (3000 ppm dietary Fe). After an iron supplementation period of 60 days, blood samples were analyzed to determine iron biomarkers, serum copper, and zinc contents. Animals were slaughtered to assess total iron, non-heme iron, heme iron, zinc, and copper contents in samples of nine meat cuts and some offal. Iron supplementation improved the iron status in pigs with increased hemoglobin and hematocrit, but did not affect serum levels of iron, zinc, and copper. Iron supplementation did not affect the heme and non-heme iron contents of the different meat cuts. Zinc contents decreased by 32–55% in meat cuts, where iron content increased in the liver, spleen, kidneys, and pancreas. No differences of zinc and copper were observed in offal samples. High concentrations of iron supplementation reduce zinc content in pork.

Heme and Non-heme Iron on Growth Performances, Blood Parameters, Tissue Mineral Concentration, and Intestinal Morphology of Weanling Pigs

This experiment was conducted to evaluate the effects of heme and non-heme iron sources on growth performances, blood parameters, tissue mineral concentration, and intestinal morphology in weanling pigs. At 25 days of age, 32 newly weaned piglets (Duroc × Landrace × Yorkshire; 8.66 ± 0.59 kg) were allocated to one of the following dietary treatments: control group (basal diet with no extra iron addition), FeSO₄ group (basal diet + 100 mg Fe/kg as FeSO₄), Fe-Gly group (basal diet + 100 mg Fe/kg as Fe-Gly), and Heme group (basal diet + 100 mg Fe/kg as Heme). Each treatment had eight replicates and one pig per replicate. The experiment lasted for 28 days. The results showed that compared with basal diet, supplement with 100 mg/kg iron can increase ADG of the piglets, especially in the late experiment period (15~28 days). Heme significantly increased the a* value of longissimus dorsi muscle of piglets when compared with other iron sources (P < 0.05). The iron supplementations had no significant effect on hematological parameters, while Fe-Gly and heme increased pigs' serum iron content on day 28 when compared with FeSO₄ and basal diet (P < 0.05). The liver iron deposition in pigs fed Fe-Gly and heme was also higher than those fed FeSO₄ or basal diet (P < 0.05). Besides, diet supplement with iron significantly increased villus height (P < 0.05) in duodenum and it had tendency to increase villus height and crypt depth ratio in duodenum (P = 0.095). In conclusion, iron supplementation in diets can improve piglet's body iron state and intestinal development, but Fe-Gly and heme exhibited better bioavailability than traditional additive of FeSO₄.

Bioavailability of Microencapsulated Iron from Fortified Bread Assessed Using Piglet Model

The aim of this study was to investigate the influence of oral iron supplementation, in the form of fortified breads, on the growth performance, health, iron status parameters, and fecal metabolome of anemic piglets. A study was conducted on 24 hybrid (Large White × Landrace × Duroc) piglets. From day 44, the post-natal 12 piglets were supplemented with 100 g of one of two experimental breads, each fortified with 21 mg of ferrous sulphate, either encapsulated or not. After one week of oral supplementation, hematological parameters (hematocrit value, hemoglobin, and red blood cells) showed statistically significant differences (p ≤ 0.05). Piglets fed with the fortified breads had higher iron concentrations in the heart, liver, and intestinal mucosa compared to anemic piglets fed with control bread. Gene expression of hepcidin, iron exporter ferroportin (IREG1), and divalent metal transporter 1 (DMT1), together with concentrations of plasma ferritin, showed no significant statistical differences between groups. Both fortified breads could be used as sources of bioavailable iron. The seven-day intervention trial showed microencapsulation to have only a mild effect on the effectiveness of iron supplementation in the form of fortified bread.

Digital gene expression profiling analysis of duodenum transcriptomes in SD rats administered ferrous sulfate or ferrous glycine chelate by gavage

The absorption of different iron sources is a trending research topic. Many studies have revealed that organic iron exhibits better bioavailability than inorganic iron, but the concrete underlying mechanism is still unclear. In the present study, we examined the differences in bioavailability of ferrous sulfate and ferrous glycinate in the intestines of SD rats using Illumina sequencing technology. Digital gene expression analysis resulted in the generation of almost 128 million clean reads, with expression data for 17,089 unigenes. A total of 123 differentially expressed genes with a |log2(fold change)| >1 and q-value < 0.05 were identified between the FeSO4 and Fe-Gly groups. Gene Ontology functional analysis revealed that these genes were involved in oxidoreductase activity, iron ion binding, and heme binding. Kyoto Encyclopedia of Genes and Genomes pathway analysis also showed relevant important pathways. In addition, the expression patterns of 9 randomly selected genes were further validated by qRT-PCR, which confirmed the digital gene expression results. Our study showed that the two iron sources might share the same absorption mechanism, and that differences in bioavailability between FeSO4 and Fe-Gly were not only in the absorption process but also during the transport and utilization process.

Effect of iron supplementation on the expression of hypoxia-inducible factor and antioxidant status in rats exposed to high-altitude hypoxia environment

Iron and oxygen are essential substance for cellular activity in body tissues. Hypoxia-inducible factors (HIFs) can respond to available oxygen changes in the cellular environment and regulate the transcription of a series of target genes. The study was conducted to investigate the effects of iron supplementation on the expression of hypoxia-inducible factor-1 alpha (HIF-1α) and antioxidant status in rats exposed to high-altitude hypoxia environment. Forty rats were divided into control (CON), hypobaric hypoxia (HH), and hypobaric hypoxia plus ferrous sulfate (FeSO4) (9.93 mg/kg body weight (BW)/day) (HFS) and hypobaric hypoxia plus iron glycinate chelate (Fe-Gly) (11.76 mg/kg BW/day) (HFG) groups. Results showed that Fe-Gly effectively alleviated weight loss and intestinal mucosa damage induced by hypobaric hypoxia, whereas FeSO4 aggravated hypobaric hypoxia-induced weight loss, liver enlargement, spleen atrophy, and intestinal damage. Iron supplementation decreased liver superoxide dismutase (T-SOD) and catalase (CAT) activity (P < 0.01) and increased iron concentration in the liver compared to HH group (P < 0.001). Moreover, Fe-Gly upregulated liver transferrin expression in messenger RNA (mRNA) level (P < 0.05) and downregulated serum erythropoietin (EPO) concentration (P < 0.01) and liver HIF-1α expression level (P < 0.05 in mRNA level; P < 0.001 in protein level) compared to HH group. The study indicated that FeSO4 supplementation at high altitudes aggravated the oxidative damage of tissues and organs that could be mediated through production of malondialdehyde (MDA) and inhibition antioxidant enzyme activities. Fe-Gly can protect hypobaric hypoxia-induced tissues injury. Moreover, iron supplementation at high altitudes affected HIF-1α-mediated regulating expression of targeting genes such as EPO and transferrin. The study highlights that iron supplementation under hypobaric hypoxia environment has possible limitation, and efficient supplementation form and dosage need careful consideration.

Kinetics absorption characteristics of ferrous glycinate in SD rats and its impact on the relevant transport protein

Ferrous glycinate (Fe-Gly) maintains high bioavailability in animals, but its exact absorption mechanism is still unknown. Here, we studied on the absorption kinetics of ferrous glycinate and its impact on the relevant transport protein in Sprague-Dawley (SD) rats. A total of 72 SD rats (male, BW 100 ± 6.25 g) were randomly allotted to three treatments. These treatments were perfused with 1 mL of normal saline, ferrous sulfate (FeSO4), and ferrous glycinate (71.35 mg/L as iron) separately. Four rats were selected from each treatment for collection of blood from the tails at certain times (15, 30, 45, 60, 75, 90, 120, 240, and 360 min) after gavage. Moreover, other six rats selected from each treatment were slaughtered for sampling after gavage at 2, 4, and 6 h to evaluate the expression of intestinal transport protein. Pharmacokinetic parameters of iron were determined by one-compartmental analysis. Compared with FeSO4, the peak plasma concentration of iron (C max) is higher in the rats given gavage with Fe-Gly (P < 0.05). Four hours after gavage with Fe-Gly, the expression of divalent metal transporter 1 (DMT1) in the duodenum is significantly decreased (P < 0.05), but the expression of ferroportin 1 (Fpn1) is significantly increased (P < 0.05). This study indicates that Fe-Gly as iron sources can be absorbed more and utilized faster than FeSO4, and they had different effects on the expression of intestinal transport protein.