Mechanisms of heme iron absorption: Current questions and controversies

Iron supplementation and iron-fortified foods: a review

About one-third of the world population is suffering from iron deficiency. Delivery of iron through diet is a practical, economical, and sustainable approach. Clinical studies have shown that the consumption of iron-fortified foods is one of the most effective methods for the prevention of iron deficiency. However, supplementing iron through diet can cause undesirable side-effects. Thus, it is essential to develop new iron-rich ingredients, iron-fortified products with high bioavailability, better stability, and lower cost. It is also essential to develop newer processing technologies for more effective fortification. This review compared the iron supplementation strategies used to treat the highly iron-deficient population and the general public. We also reviewed the efficacy of functional (iron-rich) ingredients that can be incorporated into food materials to produce iron-fortified foods. The most commonly available foods, such as cereals, bakery products, dairy products, beverages, and condiments are still the best vehicles for iron fortification and delivery.Scope of reviewThe manuscript aims at providing a comprehensive review of the latest publications that cover three aspects: administration routes for iron supplementation, iron-rich ingredients used for iron supplementation, and iron-fortified foods.

Iron-Enriched Nutritional Supplements for the 2030 Pharmacy Shelves

Iron deficiency (ID) affects people of all ages in many countries. Due to intestinal blood loss and reduced iron absorption, ID is a threat to IBD patients, women, and children the most. Current therapies can efficiently recover normal serum transferrin saturation and hemoglobin concentration but may cause several side effects, including intestinal inflammation. ID patients may benefit from innovative nutritional supplements that may satisfy iron needs without side effects. There is a growing interest in new iron-rich superfoods, like algae and mushrooms, which combine antioxidant and anti-inflammatory properties with iron richness.

Structure, functional properties and iron bioavailability of Pneumatophorus japonicus myoglobin and its glycosylation products

Developing safe and efficient iron supplements is significant for the alleviation of iron-deficient anemia (IDA). Myoglobin (Mb) is a heme-protein rich in bioavailable iron. Pneumatophorus japonicus (P. japonicus), one important economic fish in China, contain a high Mb level in its dark meat normally discarded during processing. The present study aimed to determine the structure, physicochemical properties, and iron bioavailability of Mb extracted from P. japonicus. Meanwhile, the effects of glycosylation, a commonly applied chemical modification of proteins, on these parameters were evaluated. Using Box-Behnken design, the optimal conditions for Mb-chitosan glycosylation were obtained: 45.07 °C, pH 6.10 and Mb/chitosan mass ratio of 6.29. The structure and functional properties of the glycosylated Mb (Mb-gly) were investigated. Compared with the original Mb, Mb-gly obtained a more ordered secondary structure. The surface hydrophobicity of Mb-gly was found to be decreased together with the observations of elevated water solubility. Moreover, glycosylation enhanced the Mb antioxidant capacity, and improved its stability in enzymatic digestion system. Regarding to the iron bioavailability, the cellular uptake of Mb‑iron was significantly higher than FeSO₄, and further elevated by glycosylation. These results provided a basis for the development of Mb-based iron supplements, promoting the utilization of fish-processing industries wastes.

Supplementation of a low-energy diet with recombinant ferritin fromPerinereissp. can be beneficial to finishing pigs

A total of 90 finishing pigs [(Yorkshire × Landrace) × Duroc] with an average body weight (BW) of 50.02 ± 1.78 kg were used in a 10 wk experiment. The pigs were distributed into three dietary treatments replicated six times with five pigs (two barrows and three gilts) per pen. The treatment diets were a positive control (PC; high-energy diet), a negative control (NC; low-energy diet), and an NC + 0.05% ferritin diet (TRT1). The supplementation of ferritin in a low-energy diet tended (P = 0.06) to increase the BW at week 5 compared with pigs fed low-energy diets without ferritin. At week 5 and overall period, the gain-to-feed ratio of pigs fed high-energy diets was higher (P < 0.05) compared with pigs fed low-energy diets. The pigs receiving a ferritin-supplemented diet had a comparable growth performance to pigs fed high-energy diets. At week 10, fecal Lactobacilli counts of pigs fed high-energy diets were higher (P < 0.05) compared with pigs fed low-energy diets. The supplementation of low-energy diets with ferritin resulted in comparable growth performance to pigs fed high-energy diets and had no adverse effect on digestibility and fecal gas emissions. Thus, it seems beneficial to include ferritin in low-energy diets of finishing pigs.

Association between Habitual Dietary Iron Intake and Glucose Metabolism in Individuals after Acute Pancreatitis

Dietary intake of iron is known to be associated with impaired glucose metabolism. However, its involvement in derangements of glucose metabolism after acute pancreatitis (AP) is not completely understood. The aim was to investigate the association between dietary iron intake and markers of glucose metabolism in individuals after an attack of AP. Fasting blood samples were collected to analyse markers of glucose metabolism (fasting plasma glucose (FPG) and haemoglobin A1c (HbA1c)). The EPIC-Norfolk food frequency questionnaire was used to determine the habitual intake of dietary iron (total, haem, and non-haem). Multivariable linear regression analyses were conducted and six statistical models were built to adjust for covariates. A total of 109 individuals after AP were studied in a cross-sectional fashion. Total iron (β (95% confidence interval) = -0.19 (-0.35, -0.05); p = 0.01 in the most adjusted model) and non-haem iron (β (95% confidence interval) = -0.19 (-0.33, -0.04); p = 0.03 in the most adjusted model) were significantly associated with FPG, consistently in all adjusted model. Total iron and non-haem iron did not have consistent significant associations with HbA1c. Dietary haem iron intake was not associated with either FPG or HbA1c. Habitual intake of dietary iron is inversely associated with FPG in individuals after an attack of AP and may be involved in the pathogenesis of new-onset diabetes after pancreatitis. Prospective longitudinal studies are now warranted to unveil the specific mechanism underlying the involvement of dietary iron.

Iron Therapy in Inflammatory Bowel Disease

The most common complication seen in inflammatory bowel disease (IBD) patients is iron deficiency anaemia (IDA). Symptoms such as chronic fatigue can be as debilitating to IBD patients as pathological symptoms of abdominal pain and diarrhoea. Recognising and correcting anaemia may be as important as managing IBD symptoms and improving overall quality of life. Thus, iron replacement should be commenced the moment IDA is identified. Although intravenous iron is now considered standard treatment for IBD patients in Europe, oral iron still appears to be the preferred option. Advantages of oral iron include greater availability, lower costs and ease of applicability. However, its multitude of side effects, impact on the microbiome and further exacerbating IBD activity can have consequences on patient compliance. The newer oral iron formulations show promising safety and efficacy data with a good side effect profile. Intravenous iron formulations bypass the gastrointestinal tract absorption thereby leading to less side effects. Multiple studies have shown its superiority compared to oral formulations although its risk for hypersensitivity reactions continue to lead to clinician hesitancy in prescribing this formulation. This article provides an updated review on diagnosis and management of IDA in IBD patients, discussing the newer oral and intravenous formulations.

Determination of the iron bioavailability, conformation, and rheology of iron-binding proteins from Tegillarca granosa

The increased interest in achieving, solely through diet, the same effect on iron levels with supplementation, leads to numerous studies on iron absorption of iron binding proteins (IBPs). The characteristics of IBPs from Tegillarca granosa (T. granosa) and its iron utilization were determined to analyze their relationship. The results showed in T. granosa, Fe(ӀӀ) was main iron form in hemoglobin (TH) and that Fe(ӀӀ) and Fe(ӀӀӀ) coexisted in ferritin (TF). After in vitro digestion, TH was easier to be digested than TF, bovine hemoglobin, and bovine ferritin. In caco-2 cells model, iron bioavailability of TH also was the best, which related to TH's superior fluid properties, higher ratios of α-helix to β-sheet and amide I to amide II. These suggest TH could be used as a good source of organic iron and provide references for application of T. granosa in human nutrition. PRACTICAL APPLICATIONS: This research investigated the iron bioavailability and structural properties of iron-binding proteins from Tegillarca granosa (T. granosa). Moreover, the effects of iron absorption in bovine hemoglobin and ferritin were compared with those from T. granosa. The results showed the hemoglobin in T. granosa had better iron bioavailability and it could be a good source of iron. These data could provide a basic instruction of the application of T. granosa in functional food production.

Maternal Dietary Factors and the Risk of Autism Spectrum Disorders: A Systematic Review of Existing Evidence

Prenatal maternal diet is a critical factor in offspring neurodevelopment. Emerging evidence suggests that prenatal diet may also play a role in the etiology autism spectrum disorder (ASD). This review summarizes studies published in English that examined prenatal nutrients or maternal diet in association with ASD from PubMed as of July 2020. Thiry-six studies from nine countries were included in this systematic review; these focused on multivitamin (n = 5), prenatal vitamin (n = 3), folic acid (FA; n = 14), Vitamin D (n = 11), polyunsaturated fatty acid or fish/supplement intake (n = 7), iron (n = 3), Vitamin B12 (n = 1), calcium (n = 1), magnesium (n = 1), and broad maternal dietary habits (n = 3). Overall, higher or moderate intake of prenatal/multivitamin, FA, and Vitamin D was associated with reductions in odds of ASD, though results have not been uniform and there is a need to clarify differences in findings based on biomarkers versus reported intake. Evidence was inconclusive or insufficient for other nutrients. Differences in the timing and measurement of these dietary factors, as well as potential residual confounding, may contribute to existing discrepancies. Key areas for future research to better understand the role of maternal diet in ASD include the need to address potential critical windows, examine the combined effect of multiple nutrients, and consider interactions with genetic or environmental factors. LAY SUMMARY: Maternal diet during pregnancy is important for child neurodevelopment. We reviewed 36 studies examining maternal diet and autism spectrum disorder (ASD) and found that prenatal vitamin/multivitamin use and adequate intake of folic acid and Vitamin D were each associated with lower likelihood of having a child with ASD. Future studies on these and other dietary factors are needed to better understand the role of maternal diet in the development of ASD. Autism Res 2020, 13: 1634-1658. © 2020 International Society for Autism Research and Wiley Periodicals LLC.

The Effects of Iron Supplementation and Fortification on the Gut Microbiota: A Review

Iron supplementation and fortification are used to treat iron deficiency, which is often associated with gastrointestinal conditions, such as inflammatory bowel disease and colorectal cancer. Within the gut, commensal bacteria contribute to maintaining systemic iron homeostasis. Disturbances that lead to excess iron promote the replication and virulence of enteric pathogens. Consequently, research has been interested in better understanding the effects of iron supplementation and fortification on gut bacterial composition and overall gut health. While animal and human trials have shown seemingly conflicting results, these studies emphasize how numerous factors influence gut microbial composition. Understanding how different iron formulations and doses impact specific bacteria will improve the outcomes of iron supplementation and fortification in humans. Furthermore, discerning the nuances of iron supplementation and fortification will benefit subpopulations that currently do not respond well to treatment.

A Review of Nutrients and Compounds, Which Promote or Inhibit Intestinal Iron Absorption: Making a Platform for Dietary Measures That Can Reduce Iron Uptake in Patients with Genetic Haemochromatosis

OBJECTIVE

To provide an overview of nutrients and compounds, which influence human intestinal iron absorption, thereby making a platform for elaboration of dietary recommendations that can reduce iron uptake in patients with genetic haemochromatosis.

DESIGN

Review. Setting. A literature search in PubMed and Google Scholar of papers dealing with iron absorption.

RESULTS

The most important promoters of iron absorption in foods are ascorbic acid, lactic acid (produced by fermentation), meat factors in animal meat, the presence of heme iron, and alcohol which stimulate iron uptake by inhibition of hepcidin expression. The most important inhibitors of iron uptake are phytic acid/phytates, polyphenols/tannins, proteins from soya beans, milk, eggs, and calcium. Oxalic acid/oxalate does not seem to influence iron uptake. Turmeric/curcumin may stimulate iron uptake through a decrease in hepcidin expression and inhibit uptake by complex formation with iron, but the net effect has not been clarified.

CONCLUSIONS

In haemochromatosis, iron absorption is enhanced due to a decreased expression of hepcidin. Dietary modifications that lower iron intake and decrease iron bioavailability may provide additional measures to reduce iron uptake from the foods. This could stimulate the patients' active cooperation in the treatment of their disorder and reduce the number of phlebotomies.

Genetic screens reveal CCDC115 as a modulator of erythroid iron and heme trafficking

Transferrin-bound iron (TBI), the physiological circulating iron form, is acquired by cells through the transferrin receptor (TfR1) by endocytosis. In erythroid cells, most of the acquired iron is incorporated into heme in the mitochondria. Cellular trafficking of heme is indispensable for erythropoiesis and many other essential biological processes. Comprehensive elucidation of molecular pathways governing and regulating cellular iron acquisition and heme trafficking is required to better understand physiological and pathological processes affecting erythropoiesis. Here, we report the first genome-wide clustered regularly interspaced short palindromic repeats (CRISPR) screens in human erythroid cells to identify determinants of iron and heme uptake, as well as heme-mediated erythroid differentiation. We identified several candidate modulators of TBI acquisition including TfR1, indicating that our approach effectively revealed players mechanistically relevant to the process. Interestingly, components of the endocytic pathway were also revealed as potential determinants of transferrin acquisition. We deciphered a role for the vacuolar-type H+ - ATPase (V- ATPase) assembly factor coiled-coil domain containing 115 (CCDC115) in TBI uptake and validated this role in CCDC115 deficient K562 cells. Our screen in hemin-treated cells revealed perturbations leading to cellular adaptation to heme, including those corresponding to trafficking mechanisms and transcription factors potentiating erythroid differentiation. Pathway analysis indicated that endocytosis and vesicle acidification are key processes for heme trafficking in erythroid precursors. Furthermore, we provided evidence that CCDC115, which we identified as required for TBI uptake, is also involved in cellular heme distribution. This work demonstrates a previously unappreciated common intersection in trafficking of transferrin iron and heme in the endocytic pathway of erythroid cells.

Pathways of heme utilization in fungi

Iron acquisition is challenging in most environments. As an alternative to elemental iron, organisms can take up iron-protoporphyrin IX, or heme. Heme can be found in decaying organic matter and is particularly prevalent in animal hosts. Fungi have evolved at least three distinct endocytosis-mediated heme uptake systems, which have been studied in detail in the organisms Candida albicans, Cryptococcus neoformans and Schizosaccharomyces pombe. Here we summarize the known molecular details of these three uptake systems that enable parasitic and saprophytic fungi to take advantage of external heme as either cellular iron or heme sources.

Can Meat and Meat-Products Induce Oxidative Stress?

High meat and meat-products consumption has been related to degenerative diseases. In addition to their saturated fatty acids and cholesterol contents, oxidation products generated during their production, storage, digestion, and metabolization have been largely implicated. This review begins by summarizing the concept of meat and meat-products by the main international regulatory agencies while highlighting the nutritional importance of their consumption. The review also dials in the controversy of white/red meat classification and insists in the need of more accurate classification based on adequate scores. Since one of the negative arguments that meat receives comes from the association of its consumption with the increase in oxidative stress, main oxidation compounds (malondialdehyde, thermaloxidized compounds, 4-hydroxy-nonenal, oxysterols, or protein carbonyls) generated during its production, storage, and metabolization, are included as a central aspect of the work. The review includes future remarks addressed to study the effects meat consumption in the frame of diet-gene interactions, stressing the importance of knowing the genetic variables that make individuals more susceptible to a possible oxidative stress imbalance or antioxidant protection. The importance of consumed meat/meat-products in the frame of a personalized nutrition reach in plant-food is finally highlighted considering the importance of iron and plant biophenols on the microbiota abundance and plurality, which in turn affect several aspects of our physiology and metabolism.

Heme as a Taste Molecule

PURPOSE OF REVIEW

The sense of taste has evolved to enable the identification of appropriate substances to consume, to acquire nutrients, and to avoid consuming potential toxins. Five basic taste classes have been recognized, although there may be others, including metallic taste, which have not been well defined. The purpose of this review was to survey available data from diverse sources to determine how much was known about the molecular basis for metallic taste.

RECENT FINDINGS

Metallic taste has been studied in the context of dysgeusia, primarily using non-heme iron as an inducer of metallic taste sensation. However, recent efforts by industry to develop plant-based meat substitutes have suggested that iron in the form of heme may be the main molecule underlying the taste of meat. Little work has been done on heme as a taste molecule. Data support a primary role for heme in metallic taste that may have evolved as part of a means to consume and preserve elemental iron for physiological needs.

Lemon Juice, Sesame Paste, and Autoclaving Influence Iron Bioavailability of Hummus: Assessment by an In Vitro Digestion/Caco-2 Cell Model

Hummus, an iron-containing plant-based dish mainly made from chickpea purée, tahini, lemon juice and garlic, could be a valuable source of iron when bioavailable. Since the processing and formulation of food influence iron bioavailability, the present study investigated for the first time, their effects on hummus. Firstly, iron bioaccessibility was assessed on eight samples (prepared according to the screening Hadamard matrix) by in vitro digestion preceding iron dialysis. Then, iron bioavailability of four selected samples was estimated by the in vitro digestion/Caco-2 cell model. Total and dialyzable iron were determined by the atomic absorption spectrometry and ferritin formation was determined using an ELISA kit. Only autoclaving, among other processes, had a significant effect on iron bioaccessibility (+9.5, p < 0.05). Lemon juice had the highest positive effect (+15.9, p < 0.05). Consequently, the effect of its acidic components were investigated based on a full factorial 23 experimental design; no significant difference was detected. Garlic's effect was not significant, but tahini's effect was negative (-8.9, p < 0.05). Despite the latter, hummus had a higher iron bioavailability than only cooked chickpeas (30.4 and 7.23 ng ferritin/mg protein, respectively). In conclusion, hummus may be a promising source of iron; further in vivo studies are needed for confirmation.

Sensorial and Nutritional Aspects of Cultured Meat in Comparison to Traditional Meat: Much to Be Inferred

Cultured meat aspires to be biologically equivalent to traditional meat. If cultured meat is to be consumed, sensorial (texture, color, flavor) and nutritional characteristics are of utmost importance. This paper compares cultured meat to traditional meat from a tissue engineering and meat technological point of view, focusing on several molecular, technological and sensorial attributes. We outline the challenges and future steps to be taken for cultured meat to mimic traditional meat as closely as possible.

The role of iron repletion in adult iron deficiency anemia and other diseases

Iron deficiency anemia (IDA) is the most prevalent and treatable form of anemia worldwide. The clinical management of patients with IDA requires a comprehensive understanding of the many etiologies that can lead to iron deficiency including pregnancy, blood loss, renal disease, heavy menstrual bleeding, inflammatory bowel disease, bariatric surgery, or extremely rare genetic disorders. The treatment landscape for many causes of IDA is currently shifting toward more abundant use of intravenous (IV) iron due to its effectiveness and improved formulations that decrease the likelihood of adverse effects. IV iron has found applications beyond treatment of IDA, and there is accruing data about its efficacy in patients with heart failure, restless leg syndrome, fatigue, and prevention of acute mountain sickness. This review provides a framework to diagnose, manage, and treat patients presenting with IDA and discusses other conditions that benefit from iron supplementation.

The Association between Maternal Dietary Iron Intake during the First Trimester of Pregnancy with Pregnancy Outcomes and Pregnancy-Related Complications

In this study, we investigated the associations of maternal dietary iron intake during the first trimester of pregnancy and pregnancy outcomes and related complications in pregnant women of Isfahan, Iran. In this prospective study, 812 healthy first-trimester singleton pregnant women were selected randomly from 20 various health centers across Isfahan city during 2015–2016. The maternal dietary iron classified into 2 groups, including heme and non-heme iron. Factors including pre-eclampsia, gestational hypertension, gestational diabetes mellitus, intrauterine growth restriction (IUGR), and nausea and vomiting in pregnancy considered as the pregnancy-related complications. Infant's birth weight, birth height, and birth head circumference were also determined as the pregnancy-outcomes. There was a significant association between total iron consumption and infant head circumference (p = 0.01). Total maternal iron (the sum of heme and non-heme iron) was negatively associated with both infant's birth height (p = 0.006) and birth weight (p = 0.02). Non-heme iron consumption is positively associated with high-risk of IUGR (p = 0.004). Heme intake was associated with an increased risk of maternal fasting blood sugar (FBS) (p = 0.04). Higher heme, non-heme, and total iron intake were associated with lower risk of pre-eclampsia (heme: crude p = 0.05; non-heme iron: adjusted p = 0.02; total iron: adjusted p = 0.05). Maternal total iron intake was directly associated with infant head circumference, whereas, negatively associated with both birth weight and birth height. High non-heme iron intake may increase the risk of IUGR, and a high intake of heme iron may increase FBS.

Metalloprotoporphyrin Inhibition of HCV NS3-4A Protease: Structure-Activity Relationships

Background

Antiviral actions of tetrapyrroles have been described in a number of systems. Our goal was to evaluate antagonism of the HCV NS3-4A protease by a variety of common porphyrins and characterize structure-activity relationships that may be useful for future drug design of HCV and related Flaviviruses.

Methods

Using fluorometric assays, common metalloprotoporphyrins (MPP) all inhibited NS3-4A protease with IC₅₀ values in low micromolar ranges [CoPP (1.4 µM) < ZnPP = MnPP = SnPP < CuPP < FePP (6.5 µM) = protoporphyrin].

Results

Lineweaver-Burk plots confirmed that MPP: NS3 inhibition was basically competitive. All tested MPPs inhibited HCV genotype 1A, 1B, 2A and 3A recombinant proteases with the same fidelity suggesting wide antagonistic capabilities. However, when the MPPs were tested in cellular incubations with HCV replicons only Zn, Fe and free-base protoporphyrin showed comparable EC₅₀ and IC₅₀ values suggesting that there may be critical differences in MPP uptake and intracellular availability. Meso, deutero, and isohematoporphyrin derivatives, with or without metal substitution, all showed less anti-protease and antiviral activities as compared to protoporphyrins, suggesting that the planar, vinyl side chains are important for protease active site binding. MPPs were also active against three common protease mutants (T54A, A156T, and V36M) with equivalent or better IC₅₀ values as compared to wild type enzyme.

Conclusion

These findings document the versatility of MPPs as antiviral agents with an expanded sensitivity for HCV genotypes and resistance to some common viral mutations. The results also suggest that further study of MPP structure and function will be useful for the development of new antiviral agents.

Characterization, dietary habits and nutritional intake of omnivorous, lacto-ovo vegetarian and vegan runners - a pilot study

BACKGROUND

The number of people preferring plant-based nutrition is growing continuously in the western world. Vegetarianism and veganism are also becoming increasingly popular among individuals participating in sport. However, whether recreationally active vegetarian and vegan populations can meet their nutritional needs is not clear.

METHODS

The purpose of this cross-sectional study was to compare the nutrient intake of omnivorous (OMN, n = 27), lacto-ovo vegetarian (LOV, n = 25) and vegan (VEG, n = 27) recreational runners (two to five training sessions per week) with intake recommendations of the German, Austrian and Swiss Nutrition Societies (Deutsche, Österreichische und Schweizerische Gesellschaften für Ernährung, D-A-CH) for the general population. Lifestyle factors and supplement intake were examined via questionnaires; dietary habits and nutrient intake were determined based on 3-day dietary records.

RESULTS

More than half of each group did not reach the recommended energy intake (OMN: 10.4, 8.70-12.1; LOV: 9.67, 8.55-10.8; VEG: 10.2, 9.12-11.3 MJ). Carbohydrate intake was slightly below the recommendations of > 50 EN% in OMN (46.7, 43.6-49.8 EN%), while LOV (49.4, 45.5-53.3 EN%) and VEG (55.2, 51.4-59.0 EN%) consumed adequate amounts (p = 0.003). The recommended protein intake of 0.8 g/kg body weight (D-A-CH) was exceeded in all three groups (OMN: 1.50, 1.27-1.66; LOV: 1.34, 1.09-1.56; VEG: 1.25; 1.07-1.42 g/kg BW; p = 0.047). Only VEG (26.3, 22.7-29.8 EN%) did not achieve the recommended fat intake of 30 EN%. The supply of micronutrients, such as vitamin D and cobalamin, was dependent on supplement intake. Additionally, female OMN and LOV achieved the recommended daily intake of 15 mg iron only after supplementation, while VEG consumed adequate amounts solely via food.

CONCLUSION

All three groups were sufficiently supplied with most nutrients despite the exceptions mentioned above. The VEG group even showed advantages in nutrient intake (e.g. carbohydrates, fiber and iron) in comparison to the other groups. However, the demand for energy and several macro- and micronutrients might be higher for athletes. Thus, it is also necessary to analyze the endogenous status of nutrients to evaluate the influence of a vegetarian and vegan diet on the nutrient supply of athletes.

TRIAL REGISTRATION

German Clinical Trial Register (DRKS00012377), registered on April 28, 2017.

Mechanism of colorectal carcinogenesis triggered by heme iron from red meat

Colorectal cancer (CRC) is one of the major tumor entities worldwide, with an increasing incidence in younger people. CRC formation is causally linked to various genetic, life-style and dietary risk factors. Among the ladder, the consumption of red meat has emerged as important risk factor contributing to CRC. A large body of evidence shows that heme iron is the critical component of red meat, which promotes colorectal carcinogenesis. In this review, we describe the uptake and cellular fate of both heme and inorganic iron in intestinal epithelial cells. Next, an overview on the DNA damaging properties of heme iron is provided, highlighting the DNA adducts relevant for CRC etiology. Moreover, heme triggered mechanisms leading to colonic hyperproliferation are presented, which are intimately linked to changes in the intestinal microbiota induced by heme. A special focus was set on the impact of heme iron on innate and adaptive immune cells, which could be relevant in the context of CRC. Finally, we recapitulate in vivo studies providing evidence for the tumor-promoting potential of dietary heme iron. Altogether, heme iron affects numerous key pathways involved in the pathogenesis of CRC.

Dietary iron chelate for sows and effects on iron supplementation in piglets

In order to evaluate iron chelate in diets for sows during gestation and lactation and its effects on iron supplementation for piglets, a total of 50 pregnant sows in the third parity order were distributed according to a randomized block design with two treatments: diet without iron chelate supplementation (n=20); diet supplemented with 0.15% of iron chelate (n=30). The litters of sows were distributed into five different treatments: sows without iron chelate supplementation and piglets receiving intramuscular iron-dextran; sows without iron chelate supplementation and piglets receiving oral iron supplementation; sows supplemented with iron chelate and piglets receiving intramuscular iron-dextran; sows supplemented with iron chelate and piglets receiving oral iron supplementation; sows supplemented with iron chelate and piglets without iron supplementation. No influence of dietary supplementation of iron chelate was verified on the productive parameters of the sows. For the piglets, iron-dextran supplementation promoted higher weaning weight in comparison to non-supplemented piglets, although not differing to those received oral iron supplementation. Thus, iron chelate supplementation did not improve the productive parameters of sows, but it increased iron excretion in the feces, thus requiring iron supplementation for the piglets after birth.

On the characteristic and stability of iron diet supplements

The iron diet supplements: AproFER 1000 and AproTHEM were subjected to various chemical, microbial and magnetic analysis. The microbial analysis revealed no presence of pathogenic bacteria in the studied products. No significant changes in iron content or forms (bivalent/trivalent) were observed in EPR analysis of supplements stored at different conditions for a long period of time. The chemical and magnetic analysis showed that both AproFER 1000 and AproTHEM contain a high concentration of bivalent iron so they can be used as an iron diet supplements.

Iron and Cancer

This review explores the multifaceted role that iron has in cancer biology. Epidemiological studies have demonstrated an association between excess iron and increased cancer incidence and risk, while experimental studies have implicated iron in cancer initiation, tumor growth, and metastasis. The roles of iron in proliferation, metabolism, and metastasis underpin the association of iron with tumor growth and progression. Cancer cells exhibit an iron-seeking phenotype achieved through dysregulation of iron metabolic proteins. These changes are mediated, at least in part, by oncogenes and tumor suppressors. The dependence of cancer cells on iron has implications in a number of cell death pathways, including ferroptosis, an iron-dependent form of cell death. Uniquely, both iron excess and iron depletion can be utilized in anticancer therapies. Investigating the efficacy of these therapeutic approaches is an area of active research that promises substantial clinical impact.

Dietary Iron Intake in Women of Reproductive Age in Europe: A Review of 49 Studies from 29 Countries in the Period 1993-2015

OBJECTIVE

Assessment of dietary iron intake in women of reproductive age in Europe.

DESIGN

Review.

SETTING

Literature search of dietary surveys reporting intake of iron using PubMed, Internet browsers, and national nutrient databases in the period 1993-2015.

SUBJECTS

Women of reproductive age.

RESULTS

49 dietary surveys/studies in 29 European countries were included. Belgium, Bosnia, Denmark, Hungary, Italy, Northern Ireland, Serbia, Scotland, Sweden, Switzerland, United Kingdom/England, and Wales reported a median/mean iron intake of 7.6-9.9 mg/day. Finland, Iceland, Ireland, the Netherlands, Norway, Poland, and Spain reported an intake of 10.0-10.7 mg/day. Austria, Estonia, France, and Russia reported an intake of 11.0-11.9 mg/day. Latvia and Germany reported an intake of 12.0-12.2 mg/day. Croatia, Lithuania, Portugal, and Slovakia reported an intake of 15.9-19.0 mg/day. The percentage of dietary iron consisting of heme iron, reported in 7 studies, varied from 4.3% in United Kingdom to 25% in Spain. Nutrient density for iron (mg iron/10 MJ, median/mean) varied from 11.8 in Sweden to 23.0 in Lithuania. The correlation between nutrient density and dietary iron was significant (p=0.0006). In most countries, the majority of women had a dietary iron intake below 15 mg/day. In Belgium, Denmark, Hungary, and Sweden, 91-95% of women had an intake below 15 mg/day. In Ireland and Germany, 61-78% had an intake below 15 mg/day.

CONCLUSIONS

In Europe, 61-97% of women have a dietary iron intake below 15 mg/day. This contributes to a low iron status in many women. We need common European standardized dietary methods, uniform dietary reference values, and uniform statistical methods to perform intercountry comparisons.

Iron intake, body iron status, and risk of breast cancer: a systematic review and meta-analysis

BACKGROUND

Iron has been shown to promote breast carcinogenesis in animal models through generation of oxidative stress and interaction with estrogen. Heme iron, which is found exclusively in animal-sourced foods, is suggested to have a more detrimental effect. Epidemiological evidence of the association between iron and breast cancer risk remains inconclusive and has not been comprehensively summarized. This systematic review and meta-analysis evaluated associations between both iron intake and body iron status and breast cancer risk.

METHODS

Four electronic databases (MEDLINE, EMBASE, CINAHL, and Scopus) were searched up to December 2018 for studies assessing iron intake and/or biomarkers of iron status in relation to breast cancer risk. Using random-effects meta-analyses, pooled relative risks (RRs) and 95% confidence intervals (CIs) were calculated comparing the highest vs. lowest category of each iron measure. Dose-response meta-analyses were also performed to investigate linear and nonlinear associations.

RESULTS

A total of 27 studies were included in the review, of which 23 were eligible for meta-analysis of one or more iron intake/status measures. Comparing the highest vs. lowest category, heme iron intake was significantly associated with increased breast cancer risk, with a pooled RR of 1.12 (95% CI: 1.04-1.22), whereas no associations were found for dietary (1.01, 95% CI: 0.89-1.15), supplemental (1.02, 95% CI: 0.91-1.13), or total (0.97, 95% CI: 0.82-1.14) iron intake. Associations of iron status indicators with breast cancer risk were generally in the positive direction; however, a significant pooled RR was found only for serum/plasma levels (highest vs. lowest) of iron (1.22, 95% CI: 1.01-1.47), but not for ferritin (1.13, 95% CI: 0.78-1.62), transferrin saturation (1.16, 95% CI: 0.91-1.47), or total iron-binding capacity (1.10, 95% CI: 0.97-1.25). In addition, a nonlinear dose-response was observed for heme iron intake and serum iron (both P_nonlinearity < 0.05).

CONCLUSIONS

Heme iron intake and serum iron levels may be positively associated with breast cancer risk. Although associations were modest, these findings may have public health implications given the widespread consumption of (heme) iron-rich foods. In light of methodological and research gaps identified, further research is warranted to better elucidate the relationship between iron and breast cancer risk.

The interaction of Hemin and Sestrin2 modulates oxidative stress and colon tumor growth

Several large epidemiological and animal studies demonstrate a direct correlation between dietary heme iron intake and/or systemic iron levels and cancer risk in several cancers including colorectal cancer (CRC). However, the precise mechanisms for how heme iron contributes to CRC and how cancer cells respond to heme iron-induced stress are still unclear. Previously we have shown that one of the stress-inducible proteins, Sestrin2 (SESN2), is a novel tumor suppressor in colon by limiting endoplasmic reticulum stress and mammalian target of rapamycin complex 1 (mTORC1) signaling and tumor growth. But the relationship between heme iron and SESN2, especially in the context of colon carcinogenesis, was not investigated previously. Here, we found that hemin dose-dependently increased SESN2 expression in an oxidative stress and nuclear factor (erythroid-derived 2)-like 2 (NFE2L2, NRF2)-dependent manner. Since SESN2 overexpression reduced hemin-induced oxidative stress, SESN2 could be an important target of NRF2 exerting antioxidant function. Indeed, expression of several oxidative stress responsive proteins such as NRF2 and its target genes was reduced by SESN2. Although we formerly reported that SESN2 expression was reduced after p53 mutation in colon tumors, mouse colon tumors, which have intact p53 and NRF2, induced SESN2 expression in response to iron stimulus. Although SESN2 overexpression decreased murine colon tumor cell growth both in vitro and in vivo, it rendered colon cancer cells more resistant to hemin-induced apoptosis and therefore promoted tumor growth during hemin treatment. Taken together, although SESN2 generally suppresses tumorigenesis, it can produce tumor-promoting role in iron-rich environment by suppressing oxidative stress-associated cancer cell death.

Efficacy of SXN in the Treatment of Iron Deficiency Anemia: A Phase IV Clinical Trial

Shengxuening (SXN) tablet is extracted from the excrement of the silkworm and has effects on hematopoiesis. The main components of SXN are chlorophyll derivatives and sodium iron chlorophyllin (SIC). The present study aims to investigate the efficiency and safety of SXN on iron deficiency anemia. This phase IV, multicenter, open-label, randomized clinical trial was conducted in 31 hospitals in China from June 2001 to April 2002. Adults and children were randomly divided into low-dose (L-SXN), medium-dose (M-SXN), and high-dose (H-SXN) groups, respectively. The course of treatment was 1 month. Peripheral hemogram levels and iron status were examined before and after treatment. Adults in all three dose groups demonstrated a significant increase in hemoglobin (HGB) concentration. Children who received SXN treatment in medium and high doses also demonstrated increased HGB concentration. Reticulocyte counts increased at the end of treatment in the M-SXN and H-SXN adult groups and in the M-SXN child group. For both children and adults, SXN in the three dose groups was found to significantly elevate red blood cell level, mean corpuscular volume, mean corpuscular hemoglobin, and mean corpuscular hemoglobin concentration. The total effective rate in the SXN-treated group reached 84.8%. The incidence of adverse events was 4.07%. The most common side effects were nausea (2.83%), diarrhea (0.74%), and rash (0.25%). SXN was proved to be efficient and safe for adults and children with iron deficiency anemia.

Association of Coffee and Tea with Ferritin: Data from the Korean National Health and Nutrition Examination Survey (IV and V)

There have been few studies that have evaluated the association between coffee intake and iron in Korean population. Data from the Korean National Health and Nutrition Examination Survey (IV and V; 2007–2012) was used to investigate the association between coffee and green tea intake and serum ferritin levels in Korean adults. Beverage intake was assessed using a food frequency questionnaire. Multivariate linear regression was performed to evaluate the relationship between coffee and tea intake and serum ferritin levels, after adjusting for age, body mass index, education level, smoking status, alcohol consumption, physical activity, hypertension, diabetes mellitus, and daily iron intake. Coffee intake was negatively related to serum ferritin levels in both sexes. The multivariate-adjusted geometric mean of serum ferritin level was 100.7 ng/mL (95% confidence interval [CI]: 98.2–103.4) in men drinking <1 coffee/day, and 92.2 ng/mL (95% CI: 89.7–94.8) in those drinking ≥3 coffees/day. In women, the equivalent serum ferritin levels were 35.6 ng/mL (95% CI: 34.8–36.4) and 28.9 ng/mL (95% CI: 27.8–30.1). However, green tea intake was not related to serum ferritin levels. In conclusion, coffee consumption was associated with lower serum ferritin levels in Korean adults.

Intersection of Iron and Copper Metabolism in the Mammalian Intestine and Liver

Iron and copper have similar physiochemical properties; thus, physiologically relevant interactions seem likely. Indeed, points of intersection between these two essential trace minerals have been recognized for many decades, but mechanistic details have been lacking. Investigations in recent years have revealed that copper may positively influence iron homeostasis, and also that iron may antagonize copper metabolism. For example, when body iron stores are low, copper is apparently redistributed to tissues important for regulating iron balance, including enterocytes of upper small bowel, the liver, and blood. Copper in enterocytes may positively influence iron transport, and hepatic copper may enhance biosynthesis of a circulating ferroxidase, ceruloplasmin, which potentiates iron release from stores. Moreover, many intestinal genes related to iron absorption are transactivated by a hypoxia-inducible transcription factor, hypoxia-inducible factor-2α (HIF2α), during iron deficiency. Interestingly, copper influences the DNA-binding activity of the HIF factors, thus further exemplifying how copper may modulate intestinal iron homeostasis. Copper may also alter the activity of the iron-regulatory hormone hepcidin. Furthermore, copper depletion has been noted in iron-loading disorders, such as hereditary hemochromatosis. Copper depletion may also be caused by high-dose iron supplementation, raising concerns particularly in pregnancy when iron supplementation is widely recommended. This review will cover the basic physiology of intestinal iron and copper absorption as well as the metabolism of these minerals in the liver. Also considered in detail will be current experimental work in this field, with a focus on molecular aspects of intestinal and hepatic iron-copper interplay and how this relates to various disease states. © 2018 American Physiological Society. Compr Physiol 8:1433-1461, 2018.

Role of iron metabolism in heart failure: From iron deficiency to iron overload

Iron metabolism is a balancing act, and biological systems have evolved exquisite regulatory mechanisms to maintain iron homeostasis. Iron metabolism disorders are widespread health problems on a global scale and range from iron deficiency to iron-overload. Both types of iron disorders are linked to heart failure. Iron play a fundamental role in mitochondrial function and various enzyme functions and iron deficiency has a particular negative impact on mitochondria function. Given the high-energy demand of the heart, iron deficiency has a particularly negative impact on heart function and exacerbates heart failure. Iron-overload can result from excessive gut absorption of iron or frequent use of blood transfusions and is typically seen in patients with congenital anemias, sickle cell anemia and beta-thalassemia major, or in patients with primary hemochromatosis. This review provides an overview of normal iron metabolism, mechanisms underlying development of iron disorders in relation to heart failure, including iron-overload cardiomyopathy, and clinical perspective on the treatment options for iron metabolism disorders.

Unraveling the Burden of Iron in Neurodegeneration: Intersections with Amyloid Beta Peptide Pathology

Iron overload is a hallmark of many neurodegenerative processes such as Alzheimer's, Parkinson's, and Huntington's diseases. Unbound iron accumulated as a consequence of brain aging is highly reactive with water and oxygen and produces reactive oxygen species (ROS) or free radicals. ROS are toxic compounds able to damage cell membranes, DNA, and mitochondria. Which are the mechanisms involved in neuronal iron homeostasis and in neuronal response to iron-induced oxidative stress constitutes a cutting-edge topic in metalloneurobiology. Increasing our knowledge about the underlying mechanisms that operate in iron accumulation and their consequences would shed light on the comprehension of the molecular events that participate in the pathophysiology of the abovementioned neurodegenerative diseases. In this review, current evidences about iron accumulation in the brain, the signaling mechanisms triggered by metal overload, as well as the interaction between amyloid β (Aβ) and iron, will be summarized.

Identification of Genes for Hereditary Hemochromatosis

Hereditary hemochromatosis (HH) is one of the most common genetically transmitted conditions in individuals of Northern European ancestry. The disease is characterized by excessive intestinal absorption of dietary iron, resulting in pathologically high iron storage in tissues and organs. If left untreated, HH can damage joints and organs, and eventually lead to death. There are four main classes of HH, as well as five individual molecular subtypes, caused by mutations in five genes, and the approaches implemented in the discovery of each HH type have specific histories and unique aspects. In this chapter, we review the genetics of the different HH types, including the strategies used to detect the causal variants in each case and the manner in which genetic variants were found to affect iron metabolism.

Hepcidin in Iron Homeostasis: Diagnostic and Therapeutic Implications in Type 2 Diabetes Mellitus Patients

The prevalence of type 2 diabetes is increasing in epidemic proportions worldwide. Evidence suggests body iron overload is frequently linked and observed in patients with type 2 diabetes. Body iron metabolism is based on iron conservation and recycling by which only a part of the daily need is replaced by duodenal absorption. The principal liver-produced peptide called hepcidin plays a fundamental role in iron metabolism. It directly binds to ferroportin, the sole iron exporter, resulting in the internalization and degradation of ferroportin. However, inappropriate production of hepcidin has been shown to play a role in the pathogenesis of type 2 diabetes mellitus and its complications, based on the regulation and expression in iron-abundant cells. Underexpression of hepcidin results in body iron overload, which triggers the production of reactive oxygen species simultaneously thought to play a major role in diabetes pathogenesis mediated both by β-cell failure and insulin resistance. Increased hepcidin expression results in increased intracellular sequestration of iron, and is associated with the complications of type 2 diabetes. Besides, hepcidin concentrations have been linked to inflammatory cytokines, matriptase 2, and chronic hepatitis C infection, which have in turn been reported to be associated with diabetes by several approaches. Either hepcidin-targeted therapy alone or as adjunctive therapy with phlebotomy, iron chelators, or dietary iron restriction may be able to alter iron parameters in diabetic patients. Therefore, measuring hepcidin may improve differential diagnosis and the monitoring of disorders of iron metabolism.

Calcium and zinc decrease intracellular iron by decreasing transport during iron repletion in an in vitro model

PURPOSE

Iron is an essential micronutrient that participates in a number of vital reactions and its absorption may be altered by various nutritional factors such as other micronutrients. Our hypothesis is that iron absorption is decreased because of the interactions with zinc and calcium. We evaluated the interaction between calcium and zinc on iron uptake and transport, intracellular Fe and Zn levels and mRNA expression of DMT1, ferroportin, Zip4 and ZnT1 in an in vitro model.

METHODS

Caco-2 cells were cultivated with 1 mM Ca; 10 or 30 µM Zn and/or 10, 20 or 30 µM Fe for 24 h.

RESULTS

Intracellular Fe decreased in cells incubated with 30 µM Zn or with the mix Ca/10 µM Zn/Fe. Zn mostly increased under Ca, Zn and Fe treatment. DMT1 mRNA expression decreased when intracellular Fe increased. Ferroportin expression displayed no change in cells cultured with different Fe concentrations. The mix of Ca, Zn and Fe increased DMT1 and ferroportin expression mainly under high Zn concentration. Zip4 expression was mostly augmented by Ca and Fe; however, ZnT1 showed no change in all conditions studied. Fe uptake was higher in all the conditions studied compared to control cells; however, Fe transport increased only in cells incubated with Fe alone. In all the other conditions, Fe transport was lower than that in control cells.

CONCLUSIONS

The present findings suggest that Ca and Zn interfere with iron metabolism. This interference is through an increase in ferroportin activity, which results in a diminished net iron absorption.

Dietary hemoglobin rescues young piglets from severe iron deficiency anemia: Duodenal expression profile of genes involved in heme iron absorption

Heme is an efficient source of iron in the diet, and heme preparations are used to prevent and cure iron deficiency anemia in humans and animals. However, the molecular mechanisms responsible for heme absorption remain only partially characterized. Here, we employed young iron-deficient piglets as a convenient animal model to determine the efficacy of oral heme iron supplementation and investigate the pathways of heme iron absorption. The use of bovine hemoglobin as a dietary source of heme iron was found to efficiently counteract the development of iron deficiency anemia in piglets, although it did not fully rebalance their iron status. Our results revealed a concerted increase in the expression of genes responsible for apical and basolateral heme transport in the duodenum of piglets fed a heme-enriched diet. In these animals the catalytic activity of heme oxygenase 1 contributed to the release of elemental iron from the protoporphyrin ring of heme within enterocytes, which may then be transported by the strongly expressed ferroportin across the basolateral membrane to the circulation. We hypothesize that the well-recognized high bioavailability of heme iron may depend on a split pathway mediating the transport of heme-derived elemental iron and intact heme from the interior of duodenal enterocytes to the bloodstream.

The iron chaperone poly(rC)-binding protein 2 forms a metabolon with the heme oxygenase 1/cytochrome P450 reductase complex for heme catabolism and iron transfer

Mammals incorporate a major proportion of absorbed iron as heme, which is catabolized by the heme oxygenase 1 (HO1)-NADPH-cytochrome P450 reductase (CPR) complex into biliverdin, carbon monoxide, and ferrous iron. Moreover, intestinal iron is incorporated as ferrous iron, which is transported via the iron importer, divalent metal transporter 1 (DMT1). Recently, we demonstrated that the iron chaperone poly(rC)-binding protein 2 (PCBP2) can directly receive ferrous iron from DMT1 or transfer iron to the iron exporter, ferroportin 1. To promote intracellular iron flux, an iron chaperone may be essential for receiving iron generated by heme catabolism, but this hypothesis is untested so far. Herein, we demonstrate that HO1 binds to PCBP2, but not to other PCBP family members, namely PCBP1, PCBP3, or PCBP4. Interestingly, HO1 formed a complex with either CPR or PCBP2, and it was demonstrated that PCBP2 competes with CPR for HO1 binding. Using PCBP2-deletion mutants, we demonstrated that the PCBP2 K homology 3 domain is important for the HO1/PCBP2 interaction. In heme-loaded cells, heme prompted HO1-CPR complex formation and decreased the HO1/PCBP2 interaction. Furthermore, in vitro reconstitution experiments with purified recombinant proteins indicated that HO1 could bind to PCBP2 in the presence of heme, whereas loading of PCBP2 with ferrous iron caused PCBP2 to lose its affinity for HO1. These results indicate that ferrous iron released from heme can be bound by PCBP2 and suggest a model for an integrated heme catabolism and iron transport metabolon.

Regulation of mitochondrial structure and function by protein import: A current review

By generating the majority of a cell's ATP, mitochondria permit a vast range of reactions necessary for life. Mitochondria also perform other vital functions including biogenesis and assembly of iron-sulfur proteins, maintenance of calcium homeostasis, and activation of apoptosis. Accordingly, mitochondrial dysfunction has been linked with the pathology of many clinical conditions including cancer, type 2 diabetes, cardiomyopathy, and atherosclerosis. The ongoing maintenance of mitochondrial structure and function requires the import of nuclear-encoded proteins and for this reason, mitochondrial protein import is indispensible for cell viability. As mitochondria play central roles in determining if cells live or die, a comprehensive understanding of mitochondrial structure, protein import, and function is necessary for identifying novel drugs that may destroy harmful cells while rescuing or protecting normal ones to preserve tissue integrity. This review summarizes our current knowledge on mitochondrial architecture, mitochondrial protein import, and mitochondrial function. Our current comprehension of how mitochondrial functions maintain cell homeostasis and how cell death occurs as a result of mitochondrial stress are also discussed.

DCYTB is a predictor of outcome in breast cancer that functions via iron-independent mechanisms

BACKGROUND

Duodenal cytochrome b (DCYTB) is a ferrireductase that functions together with divalent metal transporter 1 (DMT1) to mediate dietary iron reduction and uptake in the duodenum. DCYTB is also a member of a 16-gene iron regulatory gene signature (IRGS) that predicts metastasis-free survival in breast cancer patients. To better understand the relationship between DCYTB and breast cancer, we explored in detail the prognostic significance and molecular function of DCYTB in breast cancer.

METHODS

The prognostic significance of DCYTB expression was evaluated using publicly available microarray data. Signaling Pathway Impact Analysis (SPIA) of microarray data was used to identify potential novel functions of DCYTB. The role of DCYTB was assessed using immunohistochemistry and measurements of iron uptake, iron metabolism, and FAK signaling.

RESULTS

High DCYTB expression was associated with prolonged survival in two large independent cohorts, together totaling 1610 patients (cohort #1, p = 1.6e-11, n = 741; cohort #2, p = 1.2e-05, n = 869; log-rank test) as well as in the Gene expression-based Outcome for Breast cancer Online (GOBO) cohort (p < 1.0e-05, n = 1379). High DCYTB expression was also associated with increased survival in homogeneously treated groups of patients who received either tamoxifen or chemotherapy. Immunohistochemistry revealed that DCYTB is localized on the plasma membrane of breast epithelial cells, and that expression is dramatically reduced in high-grade tumors. Surprisingly, neither overexpression nor knockdown of DCYTB affected levels of ferritin H, transferrin receptor, labile iron or total cellular iron in breast cancer cells. Because SPIA pathway analysis of patient microarray data revealed an association between DCYTB and the focal adhesion pathway, we examined the influence of DCYTB on FAK activation in breast cancer cells. These experiments reveal that DCYTB reduces adhesion and activation of focal adhesion kinase (FAK) and its adapter protein paxillin.

CONCLUSIONS

DCYTB is an important predictor of outcome and is associated with response to therapy in breast cancer patients. DCYTB does not affect intracellular iron in breast cancer cells. Instead, DCYTB may retard cancer progression by reducing activation of FAK, a kinase that plays a central role in tumor cell adhesion and metastasis.

The effect of amino acid deprivation on the transfer of iron through Caco-2 cell monolayers

Iron (Fe) metabolism is modified by many nutritional factors. Amino acids (AA) play a central role in various biological processes, such as protein synthesis and energy supply. However, the influence of AA status on iron metabolism has not been investigated. Here, we test whether AA alters iron metabolism in an intestinal cell model. Both Fe uptake and transfer across the cell monolayer were significantly increased by non-essential AA deficiency (both p<0.001) while only Fe transfer was increased by essential AA deficiency (p<0.0001). Both essential and non-essential AA deficiency decreased DMT1 (±IRE) exon1A mRNA expression (respectively p=0.0007 and p=0.006) and increased expression of ferritin heavy chain. DMT1+IRE (also expressing exon1A or 1B) mRNA levels were decreased by essential AA deficiency (p=0.012). The mRNA levels of total DMT1 were also decreased by essential, but not non-essential, AA deficiency (p=0.006). Hepcidin levels were increased significantly by non-essential amino acid deprivation (p=0.047). Protein levels of ferroportin and/or ferritin heavy chain were not altered by AA deficiency, suggesting that they had no effect on Fe efflux or storage in the cell, though iron content of ferritin could be increased. Our data demonstrate, for the first time, that AA status affects iron transport and the expression of genes related to iron metabolism in Caco-2 cells, although the changes observed are not sufficient to explain the alteration in iron transport. We hypothesise that the effect on Fe transfer is mediated through an increased movement across the cell layer, rather than transfer across the cell membranes.

Efficacy of iron-supplement bars to reduce anemia in urban Indian women: a cluster-randomized controlled trial

Background: India's high prevalence of iron-deficiency anemia has largely been attributed to the local diet consisting of nonheme iron, which has lower absorption than that of heme iron.Objective: We assessed the efficacy of the consumption of iron-supplement bars in raising hemoglobin concentrations and hematocrit percentages in anemic (hemoglobin concentration <12 g/dL) Indian women of reproductive age.Design: The Let's be Well Red study was a 90-d, pair-matched, cluster-randomized controlled trial. A total of 361 nonpregnant women (age 18-35 y) were recruited from 10 sites within Mumbai and Navi Mumbai, India. All participants received anemia education and a complete blood count (CBC). Random assignment of anemic participants to intervention and control arms occurred within 5 matched site-pairs. Intervention participants received 1 iron-supplement bar (containing 14 mg Fe)/d for 90 d, whereas control subjects received nothing. CBC tests were given at days 15, 45, and 90. Primary outcomes were 90-d changes from baseline in hemoglobin concentrations and hematocrit percentages. Linear mixed models and generalized estimating equations were used to model continuous and binary outcomes, respectively.Results: Of 179 anemic participants, 136 (76.0%) completed all follow-up assessments (65 intervention and 71 control participants). Baseline characteristics were comparable by arm. Mean hemoglobin and hematocrit increases after 90 d were greater for intervention than for control participants [1.4 g/dL (95% CI: 1.3, 1.6 g/dL) and 2.7% (95% CI: 2.2%, 3.2%), respectively]. The anemia prevalence at 90 d was lower for intervention (29.2%) than for control participants (98.6%) (OR: 0.007; 95% CI: 0.001, 0.04).Conclusions: The daily consumption of an iron-supplement bar leads to increased hemoglobin concentrations and hematocrit percentages and to a lower anemia prevalence in the target population with no reported side effects. This intervention is an attractive option to combat anemia in India. This trial was registered at clinicaltrials.gov as NCT02032615.

Iron in red meat-friend or foe

In developed countries, due to high content and bioavailability, red and processed meats are the main sources of iron in the diet. Adequate intake of this nutrient is essential for the proper development and functioning of the human body, and its deficiencies are associated mainly with the occurrence of anemia, which is one of the most widespread nutritional problems in the world. However, excessive intake of iron can be detrimental to health. Studies have shown that high consumption of red meat and its products, and thereby iron, particularly in the form of heme, increases the risk of non-communicable diseases, including cancers, type II diabetes and cardiovascular disease. Due to the high nutritional value, the presence of red meat in the diet is preferable, but according to World Cancer Research Fund International its consumption should not exceed 500g per week. Furthermore, there are several potential ways to suppress the toxic effects of heme iron in the diet.

Heme Iron Release from Alginate Beads at In Vitro Simulated Gastrointestinal Conditions

Heme iron (Fe) release from alginate beads at in vitro simulated gastrointestinal conditions for potential use as oral heme Fe supplement was studied. Five beads at different ratios of sodium alginate (SA)-to-spray-dried bovine blood cells (SDBC) with weight ratios of 1:1.25, 1:2.5, 1:5, 1:10, and 1:15 (w/w) were prepared. Release characteristics of these beads were investigated at in vitro simulated gastrointestinal conditions. Release media pH strongly influenced the controlled Fe release from the beads. The heme Fe-beads in simulated gastric fluid (pH 2) remained in a shrinkage state and Fe release was low: 25.8, 21.1, 11.6, 12.1, and 12.0 % for 1:1.25, 1:2.5, 1:5, 1:10, and 1:15 ratios, respectively. Proportion and amount of Fe released by 1:1.25 and 1:2.5 ratios was higher than the other ratios. The heme Fe-beads swelled and dissociated in simulated intestinal fluid (pH 6), releasing three-fourths of the Fe in 200 min. The morphology studies showed that Fe release followed formation of pores in the alginate matrix, generating erosion of the beads and complete disintegration after 75 and 200 min of gastric and intestinal incubation, respectively. These results indicate that heme Fe-beads may be useful for oral delivery of heme Fe supplement.