Iron bis-glycine chelate competes for the nonheme-iron absorption pathway

The role of oral iron in the treatment of adults with iron deficiency

Iron deficiency is the most common nutrient deficiency in the world, affecting over 20% of premenopausal women worldwide. Oral iron supplementation is often the first-line treatment for the acute and chronic management of iron deficiency due to its ease and accessibility. However, there is no consensus on the optimal formulation or dosing strategy, or which patients should be preferentially treated with intravenous iron. Management of iron deficiency is complicated by the hepcidin-ferroportin iron regulatory pathway, which has evolved to prevent iron overload and thereby creates an inherent limit on gastrointestinal iron uptake and efficacy of oral iron. Unabsorbed iron propagates many of the side effects that complicate oral iron use including dyspepsia and constipation, all of which can thus be exacerbated by excessive oral iron doses. Daily low dose and every other day dosing protocols have attempted to bypass this physiologic bottleneck to allow for effective absorption and limit side effects; however, this approach has still resulted in low fractional iron absorption. In the following manuscript, we review the pathophysiology of iron absorption and current evidence for various preparations of oral iron. Lastly, we highlight opportunities for further study to advance the care of individuals affected by iron deficiency.

Iron delivery systems for controlled release of iron and enhancement of iron absorption and bioavailability

Iron deficiency is a global nutritional problem, and adding iron salts directly to food will have certain side effects on the human body. Therefore, there is growing interest in food-grade iron delivery systems. This review provides an overview of iron delivery systems, with emphasis on the controlled release of iron during gastrointestinal digestion, as well as the enhancement of iron absorption and bioavailability. Iron-bearing proteins are easily degraded by digestive enzymes and absorbed through receptor-mediated endocytosis. Instead, protein aggregates are slowly degraded in the stomach, which delays iron release and serves as a potential iron supplement. Amino acids, peptides and polysaccharides can bind iron through iron binding sites, but the formed compounds are prone to dissociation in the stomach. Moreover, peptides and polysaccharides can deliver iron by mediating the formation of ferric oxyhydroxide which is absorbed through endocytosis or bivalent transporter 1. In addition, liposomes are unstable during gastric digestion and iron is released in large quantities. Complexes formed by polysaccharides and proteins, and microcapsules formed by polysaccharides can delay the release of iron in the gastric environment and prolong iron release in the intestinal environment. This review is conducive to the development of iron functional ingredients and dietary supplements.

Dietary Supplementation of Ferrous Glycine Chelate Improves Growth Performance of Piglets by Enhancing Serum Immune Antioxidant Properties, Modulating Microbial Structure and Its Metabolic Function in the Early Stage

The present research aimed to explore the effect of dietary ferrous glycine chelate supplementation on performance, serum immune-antioxidant parameters, fecal volatile fatty acids, and microbiota in weaned piglets. A total of 80 healthy piglets (weaned at 28 day with an initial weight of 7.43 ± 1.51 kg) were separated into two treatments with five replicates of eight pigs each following a completely randomized block design. The diet was a corn-soybean basal diet with 2,000 mg/kg ferrous glycine chelates (FGC) or not (Ctrl). The serum and fecal samples were collected on days 14 and 28 of the experiment. The results indicated that dietary FGC supplementation improved (p < 0.05) the average daily gain and average daily feed intake overall, alleviated (p < 0.05) the diarrhea rate of piglets at the early stage, enhanced (p < 0.05) the levels of superoxide dismutase and catalase on day 14 and lowered (p < 0.05) the MDA level overall. Similarly, the levels of growth hormone and serum iron were increased (p < 0.05) in the FGC group. Moreover, dietary FGC supplementation was capable of modulating the microbial community structure of piglets in the early period, increasing (p < 0.05) the abundance of short-chain fatty acid-producing bacteria Tezzerella, decreasing (p < 0.05) the abundance of potentially pathogenic bacteria Slackia, Olsenella, and Prevotella as well as stimulating (p < 0.05) the propanoate and butanoate metabolisms. Briefly, dietary supplemented FGC ameliorates the performance and alleviated the diarrhea of piglets by enhancing antioxidant properties, improving iron transport, up-regulating the growth hormone, modulating the fecal microbiota, and increasing the metabolism function. Therefore, FGC is effective for early iron supplementation and growth of piglets and may be more effective in neonatal piglets.

Iron Transport from Ferrous Bisglycinate and Ferrous Sulfate in DMT1-Knockout Human Intestinal Caco-2 Cells

This experiment was conducted to investigate the transport characteristics of iron from ferrous bisglycinate (Fe-Gly) in intestinal cells. The divalent metal transporter 1 (DMT1)-knockout Caco-2 cell line was developed by Crispr-Cas9, and then the cells were treated with ferrous sulfate (FeSO₄) or Fe-Gly to observe the labile iron pool and determine their iron transport. The results showed that the intracellular labile iron increased significantly with Fe-Gly or FeSO₄ treatment, and this phenomenon was evident over a wide range of time and iron concentrations in the wild-type cells, whereas in the knockout cells it increased only after processing with high concentrations of iron for a long time (p < 0.05). DMT1-knockout suppressed the synthesis of ferritin and inhibited the response of iron regulatory protein 1 (IRP-1) and IRP-2 to these two iron sources. The expression of peptide transporter 1 (PepT1) was not altered by knockout or iron treatment. Interestingly, the expression of zinc-regulated transporter (ZRT) and iron-regulated transporter (IRT)-like protein 14 (Zip14) was elevated significantly by knockout and iron treatment in wild-type cells (p < 0.05). These results indicated that iron from Fe-Gly was probably mainly transported into enterocytes via DMT1 like FeSO₄; Zip14 may play a certain role in the intestinal iron transport.

Iron Bisglycinate Chelate and Polymaltose Iron for the Treatment of Iron Deficiency Anemia: A Pilot Randomized Trial

BACKGROUND

Iron Deficiency Anemia (IDA) is a major public health problem worldwide. Iron Bisglycinate Chelate (FeBC) and polymaltose iron (FeP) are used for the treatment of IDA and exhibit good tolerability with a low incidence of adverse effects. However, these compounds have important differences in their structures and bioavailability.

OBJECTIVE

To compare the efficacy of oral supplementation with FeBC and FeP in anemic children.

METHODS

In this double-blind study, children aged 1 to 13 years who were diagnosed with IDA were randomly divided into two groups: i) FeBC, supplemented with iron bisglycinate chelate, and ii) FeP, supplemented with polymaltose iron (3.0 mg iron/kg body weight/day for 45 days for both groups).

RESULTS

Both treatments resulted in significant increases in hemoglobin levels, Mean Corpuscular Volume (MCV) and Cell Distribution Width (RDW) and in a reduction of transferrin levels, relative to initial values. However, only FeBC treatment significantly increased ferritin and Mean Corpuscular Hemoglobin (MCH) levels. A significant negative correlation was observed between the increase in ferritin and initial hemoglobin levels in the FeBC group, indicating that the absorption of FeBC is regulated by the body iron demand.

CONCLUSION

These results provide preliminary evidence to suggest a greater efficacy of FeBC than FeP in increasing iron stores.

Protein Hydrolysates as Promoters of Non-Haem Iron Absorption

Iron (Fe) is an essential micronutrient for human growth and health. Organic iron is an excellent iron supplement due to its bioavailability. Both amino acids and peptides improve iron bioavailability and absorption and are therefore valuable components of iron supplements. This review focuses on protein hydrolysates as potential promoters of iron absorption. The ability of protein hydrolysates to chelate iron is thought to be a key attribute for the promotion of iron absorption. Iron-chelatable protein hydrolysates are categorized by their absorption forms: amino acids, di- and tri-peptides and polypeptides. Their structural characteristics, including their size and amino acid sequence, as well as the presence of special amino acids, influence their iron chelation abilities and bioavailabilities. Protein hydrolysates promote iron absorption by keeping iron soluble, reducing ferric iron to ferrous iron, and promoting transport across cell membranes into the gut. We also discuss the use and relative merits of protein hydrolysates as iron supplements.

Improvement the nutritional status of pre-school children following intervention with a supplement containing iron, zinc, copper, vitamin A, vitamin C and prebiotic

Abstract This study investigated the effects of a vitamin and mineral fortified powder product supplemented with inulin, on the iron and vitamin A status of 110 pre-schools childrens in Viçosa, MG, Brazil. The 2 to 5-year-old children were submitted to anthropometric (weight and height), biochemical (erythrocytes, hemoglobin, mean corpuscular volume – MCV, mean corpuscular hemoglobin - MCH, serum iron, ferritin and serum retinol) and dietary (direct food weighing, 24 h recall, and food intake record) evaluations, at the beginning and at the end of a 45-day intervention. The supplement (30 g) was provided daily as part of the afternoon snack, diluted in 100 mL of water, 5 times/week and it supplied 30% of the recommended daily doses of iron, zinc, copper and vitamins A and C. Dietary and biochemical data was compared by the Wilcoxon test, and anthropometric data by the paired t-test. Values of z-scores for weight and height, erythrocytes, hemoglobin, MCV, MCH and ferritin were significantly higher after intervention; no change was observed in serum retinol. The prebiotic-containing supplement significantly increased the intake of energy, macro and micronutrients, and was effective in improving the iron and anthropometric status.

Dosage Effect of Zinc Glycine Chelate on Zinc Metabolism and Gene Expression of Zinc Transporter in Intestinal Segments on Rat

Zinc plays an essential role in various fundamental biological processes. The focus of this research was to investigate the dosage effect of zinc glycine chelate (Zn-Gly) on zinc metabolism and the gene expression of zinc transporters in intestinal segments. A total of 30 4-week-old SD rats were randomized into five treatment groups. The basal diets for each group were supplemented with gradient levels of Zn (0, 30, 60, 90, and 180 mg/kg) from Zn-Gly. After 1-week experiment, the results showed that serum and hepatic zinc concentration were elevated linearly with supplemental Zn levels from 0 to 180 mg Zn/kg. Serum Cu-Zn SOD activities resulted in a significant (P < 0.01) quadratic response and reached the peak when fed 60 mg Zn/kg. There were linear responses to the addition of Zn-Gly from 0 to 180 mg Zn/kg on Cu-Zn SOD and AKP activities in the liver. In the duodenum, MT1 mRNA was upregulated with the increasing dietary Zn-Gly levels and reached the peak of 180 mg Zn/kg (P < 0.05). Zip4 mRNA expression was downregulated with the increasing zinc levels (P < 0.05) in both duodenum and jejunum. In the jejunum, Zip5 mRNA expression in 60 mg Zn/kg was higher compared with other groups (P < 0.05). ZnT1 mRNA in duodenum was numerically increased with the rising levels of zinc content and was significantly higher (P < 0.05) with 180 mg Zn/kg. In the duodenum, adding 60 or 90 mg Zn/kg increased PepT1 expression, but in the jejunum, 60 mg Zn/kg did not differ from 0 added Zn. In summary, there is a dose-dependent effect of dietary Zn-Gly on serum and hepatic zinc levels and the activities of Cu-Zn SOD and AKP on rats. Dietary Zn-Gly has a certain effect on MT1, Zip4, Zip5, and ZnT1 expression, which expressed differently in intestinal segments with different levels of Zn-Gly load. Besides, Zn-Gly also could regulate PepT1 expression in intestinal segments.

β-Aminobutyric acid (BABA)-induced resistance in Arabidopsis thaliana: link with iron homeostasis

β-Aminobutyric acid (BABA) is a nonprotein amino acid inducing resistance in many different plant species against a wide range of abiotic and biotic stresses. Nevertheless, how BABA primes plant natural defense reactions remains poorly understood. Based on its structure, we hypothesized and confirmed that BABA is able to chelate iron (Fe) in vitro. In vivo, we showed that it led to a transient Fe deficiency response in Arabidopsis thaliana plants exemplified by a reduction of ferritin accumulation and disturbances in the expression of genes related to Fe homeostasis. This response was not correlated to changes in Fe concentrations, suggesting that BABA affects the availability or the distribution of Fe rather than its assimilation. The phenotype of BABA-treated plants was similar to those of plants cultivated in Fe-deficient conditions. A metabolomic analysis indicated that both BABA and Fe deficiency induced the accumulation of common metabolites, including p-coumaroylagmatine, a metabolite previously shown to be synthesized in several plant species facing pathogen attack. Finally, we showed that the protective effect induced by BABA against Botrytis cinerea was mimicked by Fe deficiency. In conclusion, the Fe deficiency response caused by BABA could bring the plant to a defense-ready state, participating in the plant resistance against the pathogens.

Effect of supplementation with ferrous sulfate or iron bis-glycinate chelate on ferritin concentration in Mexican schoolchildren: a randomized controlled trial

Background

Iron deficiency is one of the most common nutritional deficiencies worldwide. It is more prevalent when iron requirements are increased during pregnancy and during growth spurts of infancy and adolescence. The last stage in the process of iron depletion is characterized by a decrease in hemoglobin concentration, resulting in iron deficiency anemia. Iron deficiency, even before it is clinically identified as anemia, compromises the immune response, physical capacity for work, and intellectual functions such as attention level. Therefore, interventions addressing iron deficiency should be based on prevention rather than on treatment of anemia. The aim of this study was to compare short- and medium-term effects on ferritin concentration of daily supplementation with ferrous sulfate or iron bis-glycinate chelate in schoolchildren with iron deficiency but without anemia.

Methods

Two hundred schoolchildren from public boarding schools in Mexico City who had low iron stores as assessed by serum ferritin concentration but without anemia were randomly assigned to a daily supplement of 30 mg/day of elemental iron as ferrous sulfate or iron bis-glycinate chelate for 12 weeks. Iron status was evaluated at baseline, one week post-supplementation (short term), and 6 months (medium term) after supplementation.

Results

Ferritin concentration increased significantly between baseline and post-supplementation as well as between baseline and 6 months after supplementation. One week post-supplementation no difference was found in ferritin concentration between iron compounds, but 6 months after supplementation ferritin concentration was higher in the group that received bis-glycinate chelate iron. However, there is no difference in the odds for low iron storage between 6 months after supplementation versus the odds after supplementation; nor were these odds different by type of supplement. Hemoglobin concentration did not change significantly in either group after supplementation.

Conclusions

Supplementing with 30 mg/d of elementary iron, either as ferrous sulfate or iron bis-glycinate chelate for 90 days, showed positive effects on increasing ferritin concentration in schoolchildren with low iron stores, and this effect persisted 6 months after supplementation.

Advantages and disadvantages of the animal models v. in vitro studies in iron metabolism: a review

Iron deficiency is the most common nutritional deficiency in the world. Special molecules have evolved for iron acquisition, transport and storage in soluble, nontoxic forms. Studies about the effects of iron on health are focused on iron metabolism or nutrition to prevent or treat iron deficiency and anemia. These studies are focused in two main aspects: (1) basic studies to elucidate iron metabolism and (2) nutritional studies to evaluate the efficacy of iron supplementation to prevent or treat iron deficiency and anemia. This paper reviews the advantages and disadvantages of the experimental models commonly used as well as the methods that are more used in studies related to iron. In vitro studies have used different parts of the gut. In vivo studies are done in humans and animals such as mice, rats, pigs and monkeys. Iron metabolism is a complex process that includes interactions at the systemic level. In vitro studies, despite physiological differences to humans, are useful to increase knowledge related to this essential micronutrient. Isotopic techniques are the most recommended in studies related to iron, but their high cost and required logistic, making them difficult to use. The depletion-repletion of hemoglobin is a method commonly used in animal studies. Three depletion-repletion techniques are mostly used: hemoglobin regeneration efficiency, relative biological values (RBV) and metabolic balance, which are official methods of the association of official analytical chemists. These techniques are well-validated to be used as studies related to iron and their results can be extrapolated to humans. Knowledge about the main advantages and disadvantages of the in vitro and animal models, and methods used in these studies, could increase confidence of researchers in the experimental results with less costs.

Iron deficiency anemia: diagnosis and management

PURPOSE OF REVIEW

Iron deficiency anemia (IDA) still remains universally problematic worldwide. The primary focus of this review is to critique articles published over the past 18 months that describe strategies for the diagnosis and management of this prevalent condition.

RECENT FINDINGS

The medical community continues to lack consensus when identifying the optimal approach for the diagnosis and management of IDA. Current diagnostic recommendations revolve around the validity and practicality of current biomarkers such as soluble transferrin-receptor concentrations and others, and cause-based diagnostics that potentially include endoscopy. Management of IDA is based on supplementation combined with effective etiological treatment. Advances in oral and parenteral low-molecular-weight iron preparations has expanded and improved treatment modalities for IDA. Since the introduction of low versus high-molecular-weight intravenous iron administration, there have been fewer serious adverse events associated with parenteral iron preparations.

SUMMARY

Best practice guidelines for diagnosing and managing IDA should include the design of an algorithm that is inclusive of multiple biomarkers and cause-based diagnostics, which will provide direction in managing IDA, and distinguish between IDA from the anemia of chronic disease.

Electrolytic iron or ferrous sulfate increase body iron in women with moderate to low iron stores

Commercial elemental iron powders (electrolytic and reduced iron), as well as heme iron supplements, were tested for efficacy in improving the iron status of women. In a randomized, double-blind trial, 51 women with moderate to low iron stores received daily for 12 wk: 1) placebo, 2) 5 mg iron as heme iron or 50 mg iron as 3) electrolytic iron, 4) reduced iron, or 5) FeSO(4). Treatments were provided in 2 capsules (heme carrier) and 3 wheat rolls (other iron sources). Differences in iron status, food nonheme iron absorption, and fecal properties were evaluated. Body iron, assessed from the serum transferrin receptor:ferritin ratio, increased significantly more in subjects administered FeSO(4) (127 +/- 29 mg; mean +/- SEM) and electrolytic (115 +/- 37 mg), but not the reduced (74 +/- 32 mg) or heme (65 +/- 26 mg) iron forms, compared with those given placebo (2 +/- 19 mg). Based on body iron determinations, retention of the added iron was estimated as 3.0, 2.7, 1.8, and 15.5%, in the 4 iron-treated groups, respectively. Iron treatments did not affect food iron absorption. The 50 mg/d iron treatments increased fecal iron and free radical-generating capacity in vitro, but did not affect fecal water cytotoxicity. In subjects administered FeSO(4), fecal water content was increased slightly but significantly more than in the placebo group. In conclusion, electrolytic iron was approximately 86% as efficacious as FeSO(4) for improving body iron, but the power of this study was insufficient to detect any efficacy of the reduced or heme iron within 12 wk. With modification, this methodology of testing higher levels of food fortification for several weeks in healthy women with low iron stores has the potential for economically assessing the efficiency of iron compounds to improve iron status.

Ferrus calcium citrate is absorbed better than iron bisglycinate in patients with Crohn's disease, but not in healthy controls

Our purpose was to compare the absorption of iron bisglycinate and ferrous calcium citrate in volunteers using an oral iron tolerance test. Twenty volunteers, 10 healthy controls and 10 with stable Crohn's disease, agreed to participate in the study. All were given 50 mg of elemental iron as iron bisglycinate or ferrous calcium citrate. Serum iron levels were monitored for 4 hr. After a week, each received the other regimen. Using the area under the curve as indicator, the oral iron absorption test revealed that absorption of iron post-ingestion of ferrous calcium citrate was better than after ingestion of iron bisglycinate for the group as a whole (P < 0.03). Volunteers with Crohn's disease absorbed ferrous calcium citrate better than iron bisglycinate (P=0.005). No difference was noted in the absorption of either preparation by healthy volunteers. Ferrus calcium citrate is apparently more effective than iron bisglycinate in patients with Crohn's disease.

The mechanisms for regulating absorption of Fe bis-glycine chelate and Fe-ascorbate in caco-2 cells are similar

Inorganic iron (Fe) absorption from the diet is controlled mainly in the intestinal tract where apical Fe uptake is inversely related to the Fe content in the enterocyte. Iron bis-glycine chelate is an iron compound that may be absorbed by a mechanism different from the regulated nonheme Fe pathway. Because Fe bis-glycine chelate is used increasingly as an Fe fortificant in foods, the critical question is whether this compound is a safe Fe supplement. We compared apical Fe uptake and transepithelial transport offered either as (59)Fe bis-glycine chelate or a (59)Fe-ascorbate (Fe-AA) complex in Caco-2 cells, as a model of human intestinal epithelia, grown in different Fe concentrations in the media (0.5, 5 and 20 micro mol/L Fe). Apical Fe uptake from (59)Fe-AA and (59)Fe bis-glycine chelate did not differ nor did transepithelial transport rates. The rate of (59)Fe uptake decreased with increasing intracellular Fe concentration (P < 0.001), an indication of a common absorption regulatory mechanism. We also evaluated the effect of an excess of Fe (100 micro mol/L) provided as Fe bis-glycine chelate or Fe-AA on the incorporation of 1 micro mol/L (55)Fe-AA into Fe-replete Caco-2 cells. The inhibition of Fe bis-glycine chelate on the absorption of the extrinsic tag of (55)Fe-AA (87.5%) did not differ from that of Fe added as Fe-AA (86.8%). These results suggest that Fe derived from Fe bis-glycine chelate and Fe-AA have similar regulatory absorption mechanisms.