Regulatory effects of Cu, Zn, and Ca on Fe absorption: the intricate play between nutrient transporters

Approaches to Address the Anemia Challenge

Anemia is a multifactorial condition; approaches to address it must recognize that the causal factors represent an ecology consisting of internal (biology, genetics, and health) and external (social/behavioral/demographic and physical) environments. In this paper, we present an approach for selecting interventions, followed by a description of key issues related to the multiple available interventions for prevention and reduction of anemia. We address interventions for anemia using the following 2 main categories: 1) those that address nutrients alone, and, 2) those that address nonnutritional causes of anemia. The emphasis will be on interventions of public health relevance, but we also consider the clinical context. We also focus on interventions at different stages of the life course, with a particular focus on women of reproductive age and preschool-age children, and present evidence on various factors to consider when selecting an intervention-inflammation, genetic mutations, nutrient delivery, bioavailability, and safety. Each section on an intervention domain concludes with a brief discussion of key research areas.

Anemia and Associated Risk Factors in Pediatric Patients

Anemia is the most common hematologic abnormality identified in children and represents a major global health problem. A delay in diagnosis and treatment might place patients with anemia at risk for the development of rare but serious complications, including chronic and irreversible cognitive impairment. Identified risk factors contributing to the development of anemia in children include the presence of nutritional deficiencies, environmental factors, chronic comorbidities, and congenital disorders of hemoglobin or red blood cells. Pediatricians, especially those in the primary care setting, serve a particularly critical role in the identification and care of those children affected by anemia. Prompt recognition of these risk factors is crucial for developing appropriate and timely therapeutic interventions and prevention strategies.

Bioavailability of Macroelements from Synbiotic Sheep's Milk Ice Cream

To determine the potential bioavailability of macroelements (Ca, Mg, P, K), probiotic ice cream samples (Lactaseibacillus paracasei L-26, Lactobacillus casei 431, Lactobacillus acidophilus LA-5, Lactaseibacillus rhamnosus and Bifidobacterium animalis ssp. lactis BB-12) from sheep's milk with inulin, apple fiber and inulin, or apple fiber and control samples were submitted to in vitro digestion in the mouth, stomach and small intestine. The bioavailability of calcium in the ice cream samples ranged from 40.63% to 54.40%, whereas that of magnesium was 55.64% to 44.42%. The highest bioavailability of calcium and magnesium was shown for the control samples. However, adding 4% inulin reduced the bioavailability of calcium by about 3-5% and magnesium only by about 5-6%. Adding 4% apple fiber reduced the bioavailability of calcium by as much as 6-12% and magnesium by 7-8%. The highest bioavailability of calcium was determined in ice cream with L. paracasei, and the highest bioavailability of magnesium was determined in ice cream with L. casei. The bioavailability of phosphorus in ice cream ranged from 47.82% to 50.94%. The highest bioavailability of phosphorus (>50%) was in sheep ice cream fermented by B. animalis. In the control ice cream, the bioavailability of potassium was about 60%. In ice cream with inulin, the bioavailability of potassium was lower by 3-4%, and in ice cream with apple fiber, the bioavailability of potassium was lower by up to 6-9%. The bioavailability of potassium was significantly influenced only by the addition of dietary fiber. The results of the study confirmed the beneficial effect of bacteria on the bioavailability of Ca, Mg and P.

Structural and functional characterisation of HepTH1-5 peptide as a potential hepcidin replacement

Hepcidin is a principal regulator of iron homeostasis and its dysregulation has been recognised as a causative factor in cancers and iron disorders. The strategy of manipulating the presence of hepcidin peptide has been used for cancer treatment. However, this has demonstrated poor efficiency and has been short-lived in patients. Many studies reported using minihepcidin therapy as an alternative way to treat hepcidin dysregulation, but this was only applied to non-cancer patients. Highly conserved fish hepcidin protein, HepTH1-5, was investigated to determine its potential use in developing a hepcidin replacement for human hepcidin (Hepc25) and as a therapeutic agent by targeting the tumour suppressor protein, p53, through structure-function analysis. The authors found that HepTH1-5 is stably bound to ferroportin, compared to Hepc25, by triggering the ferroportin internalisation via Lys42 and Lys270 ubiquitination, in a similar manner to the Hepc25 activity. Moreover, the residues Ile24 and Gly24, along with copper and zinc ligands, interacted with similar residues, Lys24 and Asp1 of Hepc25, respectively, showing that those molecules are crucial to the hepcidin replacement strategy. HepTH1-5 interacts with p53 and activates its function through phosphorylation. This finding shows that HepTH1-5 might be involved in the apoptosis signalling pathway upon a DNA damage response. This study will be very helpful for understanding the mechanism of the hepcidin replacement and providing insights into the HepTH1-5 peptide as a new target for hepcidin and cancer therapeutics.Communicated by Ramaswamy H. Sarma.

Environmental Metal Exposure, Neurodevelopment, and the Role of Iron Status: a Review

PURPOSE OF REVIEW

Exposure to environmental metals, like lead (Pb), manganese (Mn), and methylmercury (Me-Hg), has consistently been implicated in neurodevelopmental dysfunction. Recent research has focused on identifying modifying factors of metal neurotoxicity in childhood, such as age, sex, and co-exposures. Iron (Fe) status is critical for normal cognitive development during childhood, and current mechanistic, animal, and human evidence suggests that Fe status may be a modifier or mediator of associations between environmental metals and neurodevelopment. The goals of this review are to describe the current state of the epidemiologic literature on the role of Fe status (i.e., hemoglobin, ferritin, blood Fe concentrations) and Fe supplementation in the relationship between metals and children's neurodevelopment, and to identify research gaps.

RECENT FINDINGS

We identified 30 studies in PubMed and EMBASE that assessed Fe status as a modifier, mediator, or co-exposure of associations of Pb, Me-Hg, Mn, copper (Cu), zinc (Zn), arsenic (As), or metal mixtures measured in early life (prenatal period through 8 years of age) with cognition in children. In experimental studies, co-supplementation of Fe and Zn was associated with better memory and cognition than supplementation with either metal alone. Several observational studies reported interactions between Fe status and Pb, Mn, Zn, or As in relation to developmental indices, memory, attention, and behavior, whereby adverse associations of metals with cognition were worse among Fe-deficient children compared to Fe-sufficient children. Only two studies quantified joint associations of complex metal mixtures that included Fe with neurodevelopment, though findings from these studies were not consistent. Findings support memory and attention as two possible cognitive domains that may be both vulnerable to Fe deficiency and a target of metals toxicity. Major gaps in the literature remain, including evaluating Fe status as a modifier or mediator of metal mixtures and cognition. Given that Fe deficiency is the most common nutritional deficiency worldwide, characterizing Fe status in studies of metals toxicity is important for informing public health interventions.

Calcium is a noncompetitive inhibitor of DMT1 on the intestinal iron absorption process: empirical evidence and mathematical modeling analysis

Iron absorption is a complex and highly controlled process where DMT1 transports nonheme iron through the brush-border membrane of enterocytes to the cytoplasm but does not transport alkaline-earth metals such as calcium. However, it has been proposed that high concentrations of calcium in the diet could reduce iron bioavailability. In this work, we investigate the effect of intracellular and extracellular calcium on iron uptake by Caco-2 cells, as determined by calcein fluorescence quenching. We found that extracellular calcium inhibits iron uptake by Caco-2 cells in a concentration-dependent manner. Chelation of intracellular calcium with BAPTA did not affect iron uptake, which indicates that the inhibitory effect of calcium is not exerted through intracellular calcium signaling. Kinetic studies performed, provided evidence that calcium acts as a reversible noncompetitive inhibitor of the iron transport activity of DMT1. Based on these experimental results, a mathematical model was developed that considers the dynamics of noncompetitive inhibition using a four-state mechanism to describe the inhibitory effect of calcium on the DMT1 iron transport process in intestinal cells. The model accurately predicts the calcein fluorescence quenching dynamics observed experimentally after an iron challenge. Therefore, the proposed model structure is capable of representing the inhibitory effect of extracellular calcium on DMT1-mediated iron entry into the cLIP of Caco-2 cells. Considering the range of calcium concentrations that can inhibit iron uptake, the possible inhibition of dietary calcium on intestinal iron uptake is discussed.

Comparison of Ferric Sodium EDTA in Combination with Vitamin C, Folic Acid, Copper Gluconate, Zinc Gluconate, and Selenomethionine as Therapeutic Option for Chronic Kidney Disease Patients with Improvement in Inflammatory Status

Anemia is one of the most frequent and earliest complications of chronic kidney disease (CKD), which impacts a patient’s quality of life and increases the risk of adverse clinical outcomes. Patients’ inflammatory status is strictly related to the occurrence of functional iron deficiency anemia (IDA) because this causes an increase in hepcidin levels with the consequent inhibition of iron absorption and release from cellular stores into blood circulation. The aim of this study was to evaluate the use of the new oral formulation based on ferric sodium EDTA in combination with vitamin C, folic acid, copper gluconate, zinc gluconate, and selenomethionine (Ferachel Forte®) in patients with moderate CKD and functional IDA, analyzing the inflammatory status in addition to iron blood parameters, in comparison with oral ferrous sulfate and liposomal iron therapies. Sixty-two elderly patients were randomly allocated to one of the following oral treatments for 6 months: ferrous sulfate (Group 1; N = 20), ferric sodium EDTA in combination (Group 2; N = 22), and ferric liposomal formulation (Group 3; N = 20). The evaluated parameters included iron profile parameters of hemoglobin (Hb), sideremia, ferritin, transferrin saturation, C-reactive protein (CRP), and hepcidin. The results showed that in Group 1, there were no improvements. In Group 2, there were statistically significant (p < 0.001) improvements in all evaluated parameters. Finally, in Group 3, there were significant improvements in all evaluated parameters except for hepcidin, which was less than that of Group 2 patients. In conclusion, the findings showed the superior efficacy of the formulation based on ferric sodium EDTA over the other oral iron sources, and that this formulation can contribute to reducing the systemic inflammatory status in patients with CKD.

Effect of Wheatgrass Juice on Nutritional Quality of Apple, Carrot, Beet, Orange and Lemon Juice

Fresh fruit and vegetable juices are commonly consumed as a valuable source of nutrients, while wheatgrass juice is, due to its nutritional value, used as a natural dietary supplement. The main aim of this research was to evaluate the effect of wheatgrass juice addition to apple, beet, carrot, orange, and lemon juice on total and in vitro bioaccessible concentrations of K, Ca, Mg, Mn, Fe, and Zn, vitamin C concentration, total phenolic and flavonoid content, and antioxidant activity. In comparison to other juices, wheatgrass juice had the highest total and in vitro bioaccessible concentrations of Ca, Mg, Mn, Fe, and Zn, while beet juice had the highest K concentration. Lemon and orange juices had the highest vitamin C concentration, while the highest total phenolic and flavonoid content were found in wheatgrass juice. After the addition of wheatgrass juice, Ca, Mg, Mn, and Zn concentration increased in all examined juices, vitamin C concentration increased in apple, beet, and carrot juice, total phenolic content increased in carrot juice, while total flavonoid content increased in apple, carrot, and orange juice. In comparison to the examined juices, wheatgrass juice has better nutritional value, and it could be used in a mixture with other juices to improve their nutritional value.

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.

Genetic Architecture Underpinning Yield Components and Seed Mineral-Nutrients in Sesame

Genetic dissection of yield components and seed mineral-nutrient is crucial for understanding plant physiological and biochemical processes and alleviate nutrient malnutrition. Sesame (Sesamum indicum L.) is an orphan crop that harbors rich allelic repertoire for seed mineral-nutrients. Here, we harness this wide diversity to study the genetic architecture of yield components and seed mineral-nutrients using a core-collection of worldwide genotypes and segregating mapping population. We also tested the association between these traits and the effect of seed nutrients concentration on their bio-accessibility. Wide genetic diversity for yield components and seed mineral-nutrients was found among the core-collection. A high-density linkage map consisting of 19,309 markers was constructed and used for genetic mapping of 84 QTL associated with yield components and 50 QTL for seed minerals. To the best of our knowledge, this is the first report on mineral-nutrients QTL in sesame. Genomic regions with a cluster of overlapping QTL for several morphological and nutritional traits were identified and considered as genomic hotspots. Candidate gene analysis revealed potential functional associations between QTL and corresponding genes, which offers unique opportunities for synchronous improvement of mineral-nutrients. Our findings shed-light on the genetic architecture of yield components, seed mineral-nutrients and their inter- and intra- relationships, which may facilitate future breeding efforts to develop bio-fortified sesame cultivars.

The Role of Fe, Zn, and Cu in Pregnancy

Iron (Fe), copper (Cu), and zinc (Zn) are microelements essential for the proper functioning of living organisms. These elements participatein many processes, including cellular metabolism and antioxidant and anti-inflammatory defenses, and also influence enzyme activity, regulate gene expression, and take part in protein synthesis. Fe, Cu, and Zn have a significant impact on the health of pregnant women and in the development of the fetus, as well as on the health of the newborn. A proper concentration of these elements in the body of women during pregnancy reduces the risk of complications such as anemia, induced hypertension, low birth weight, preeclampsia, and postnatal complications. The interactions between Fe, Cu, and Zn influence their availability due to their similar physicochemical properties. This most often occurs during intestinal absorption, where metal ions compete for binding sites with transport compounds. Additionally, the relationships between these ions have a great influence on the course of reactions in the tissues, as well as on their excretion, which can be stimulated or delayed. This review aims to summarize reports on the influence of Fe, Cu, and Zn on the course of single and multiple pregnancies, and to discuss the interdependencies and mechanisms occurring between Fe, Cu, and Zn.

Anemia of Chronic Diseases: Wider Diagnostics-Better Treatment?

Anemia of chronic diseases is a condition that accompanies a specific underlying disease, in which there is a decrease in hemoglobin, hematocrit and erythrocyte counts due to a complex process, usually initiated by cellular immunity mechanisms and pro-inflammatory cytokines and hepcidin. This is the second most common type of anemia after iron deficiency anemia in the world. Its severity generally correlates with the severity of the underlying disease. This disease most often coexists with chronic inflammation, autoimmune diseases, cancer, and kidney failure. Before starting treatment, one should undertake in-depth diagnostics, which includes not only assessment of complete blood count and biochemical parameters, but also severity of the underlying disease. The differential diagnosis of anemia of chronic diseases is primarily based on the exclusion of other types of anemia, in particular iron deficiency. The main features of anemia of chronic diseases include mild to moderate lowering of hemoglobin level, decreased percentage of reticulocyte count, low iron and transferrin concentration, but increased ferritin. Due to the increasingly better knowledge of the pathomechanism of chronic diseases and cancer biology, the diagnosis of this anemia is constantly expanding with new biochemical indicators. These include: the concentration of other hematopoietic factors (folic acid, vitamin B₁₂), hepcidin, creatinine and erythropoietin. The basic form of treatment of anemia of chronic diseases remains supplementation with iron, folic acid and vitamin B₁₂ as well as a diet rich in the above-mentioned hematopoietic factors. The route of administration (oral, intramuscular or intravenous) requires careful consideration of the benefits and possible side effects, and assessment of the patient’s clinical status. New methods of treating both the underlying disease and anemia are raising hopes. The novel methods are associated not only with supplementing deficiencies, but also with the administration of drugs molecularly targeted to specific proteins or receptors involved in the development of anemia of chronic diseases.

Versatile Colorimetric Chemosensor Based on Bis(rhodamine) B Hydrazone for Rapid Detection of Multi-Analytes (Fe3+, Bi3+, Cu2+, and Hg2+) in Aqueous Media

A new bis(rhodamine) B hydrazone L, bearing two rhodamine chromophores, has been designed and synthesised in 70% yield. The chemical structure of the new ligand L was characterised using different spectroscopic techniques. The receptor L was utilised for rapid ‘naked eye’ detection of Fe3+, Bi3+, Cu2+, and Hg2+ in THF–H2O (1:1, v/v) by displaying significant colour changes. The mechanism of detection of metal ions was based on the ring-opening of the spirolactam rings of L upon recognition. UV/Vis spectrometry was employed to investigate L–metal ion interactions in THF–H2O (1:1, v/v). The stoichiometries of the complexes were determined using Job’s method, which revealed 1:2L–metal ion stoichiometries in the case of L–(Fe3+/Bi3+/Hg2+) complexes, while a 1:1L–metal ion stoichiometry was recognised for the L–Cu2+ complex. 1H NMR spectroscopy was applied to study the L–metal ion interactions in DMSO-d6 and results are presented.

Maternal iron-deficiency is associated with premature birth and higher birth weight despite routine antenatal iron supplementation in an urban South African setting: The NuPED prospective study

Background

Recent studies are suggesting a U-shaped relationship between antenatal iron exposure and birth outcomes. Little is known about the iron status and associated birth outcomes of pregnant women in South Africa. Our aim was to assess iron status at early, mid- and late pregnancy, and to determine associations with gestational age and birth weight in women in Johannesburg, South Africa.

Methods

In this prospective study of 250 pregnant women, we measured haemoglobin, biomarkers of iron status and inflammation at <18, 22 and 36 weeks of gestation, plus birth weight and gestational age at delivery. Associations of anaemia and iron status with birth outcomes were determined using regression models adjusted for confounders.

Results

At enrolment, the prevalence of anaemia, iron depletion (ID) and iron deficiency erythropoiesis (IDE) was 29%, 15% and 15%, respectively, and increased significantly with pregnancy progression. Anaemia and ID at 22 weeks, as well as IDE at 36 weeks were associated with higher birth weight (β = 135.4; 95% CI: 4.8, 266.1 and β = 205.4; 95% CI: 45.6, 365.1 and β = 178.0; 95% CI: 47.3, 308.7, respectively). Women in the lowest ferritin quartile at 22 weeks gave birth to babies weighing 312 g (95% CI: 94.8, 528.8) more than those in the highest quartile. In contrast, IDE at 22 weeks was associated with a higher risk for premature birth (OR: 3.57, 95% CI: 1.24, 10.34) and women in lower haemoglobin quartiles at <18 weeks had a shorter gestation by 7 days (β = -6.9, 95% CI: -13.3, -0.6) compared to those in the highest quartile.

Conclusion

Anaemia, ID and IDE prevalence increased during pregnancy despite routine iron supplementation. ID and anaemia at mid-pregnancy were associated with higher birth weight, while IDE was associated with premature birth. These results suggest that current antenatal screening and supplementation practices in South Africa need to be revisited.

Enhanced intestinal absorption of micronutrients in streptozotocin-induced diabetic rats maintained on zinc supplementation

In view of the deficiency of zinc concomitant with other minerals in diabetic condition, it is desirable to increase the absorption capability of the same by improving the intestinal health. In continuation of our previous report on the virtue of zinc supplementation on diabetic complications, and a significant favourable consequence in the restoration of the compromised structural integrity of small intestines in diabetic situation, it would be relevant to examine the permeability characteristics of the intestines. Groups of hyperglycemic rats were treated for six weeks with supplemental zinc (5-times and 10-times of normal level) to examine its possible influence on intestinal absorption of trace elements zinc, iron and calcium. Everted segments of isolated duodenum, jejunum and ileum portions of small intestine excised from these rats were evaluated for ex vivo uptake of iron, zinc and calcium from the incubation medium containing mineral fortified digesta of finger millet as a provider of these trace minerals. The extent of ex vivo uptake of zinc, iron, and calcium was severely compromised in the intestinal segments isolated from diabetic rats suggesting the loss of functional integrity concomitant with diminished ultra-structural integrity. This was more prominent in the case of iron uptake followed by that of calcium and zinc. Treatment with supplemental zinc improved the mineral uptake ex vivo by the isolated intestinal segments, which was maximum for iron followed by zinc and calcium. This favourable influence was seen more in the jejunal segment probably as a result of improving the expression of applicable transporter protein (s) as observed previously. Thus, dietary zinc supplementation was evinced here to have a promoting stimulus on the intestinal absorption of zinc, iron and calcium, which could encourage a dietary approach to counter the dyshomeostatic state of these trace elements prevalent in diabetes.

Potential of Food Hydrolyzed Proteins and Peptides to Chelate Iron or Calcium and Enhance their Absorption

Iron and calcium are two essential micronutrients that have strong effects on nutrition and human health because of their involvement in several biological and redox processes. Iron is responsible for electron and oxygen transport, cell respiration, and gene expression, whereas calcium is responsible for intracellular metabolism, muscle contraction, cardiac function, and cell proliferation. The bioavailability of these nutrients in the body is dependent on enhancers and inhibitors, some of which are found in consumed foods. Hydrolyzed proteins and peptides from food proteins can bind these essential minerals in the body and facilitate their absorption and bioavailability. The binding is also important because excess free iron will increase oxidative stress and the risks of developing chronic diseases. This paper provides an overview of the function of calcium and iron, and strategies to enhance their absorption with an emphasis on hydrolyzed proteins and peptides from foods. It also discusses the relationship between the structure of peptides and their potential to act as transition metal ligands.

Effect of Traditional Household Processes on Iron, Zinc and Copper Bioaccessibility in Black Bean (Phaseolus vulgaris L.)

Micronutrient deficiencies are a major public health problem. Beans are an important plant-based source of iron, zinc and copper, but their absorption is reduced in the presence of anti-nutrients such as phytates, polyphenols and tannins. Soaking and discarding the soaking water before cooking is unanimously recommended, but this can result in mineral loss. Data on the consequences for mineral bioaccessibility is still limited. This study aimed to evaluate iron, zinc and copper bioaccessibility in black beans cooked (regular pan, pressure cooker) with and without the soaking water. For that, three batches of black beans were investigated in triplicate, each split in nine parts (raw grains and four different household processes in duplicate) and analyzed by applying the quarter technique, resulting in a grand total of 164 samples. Minerals were quantified by ICP-MS (inductively coupled plasma mass spectrometry), myo-inositol phosphates (InsP₅, InsP₆) by HPLC (high-performance liquid chromatography) ion-pair chromatography, total polyphenols using Folin-Denis reagent and condensed tannins using Vanillin assay. Mineral bioaccessibility was determined by in vitro digestion and dialysis. All treatments resulted in a statistically significant reduction of total polyphenols (30%) and condensed tannins (20%). Only when discarding the soaking water a loss of iron (6%) and copper (30%) was observed, and InsP₆ was slightly decreased (7%) in one treatment. The bioaccessibility of iron and zinc were low (about 0.2% iron and 35% zinc), but copper presented high bioaccessibility (about 70%). Cooking beans under pressure without discarding the soaking water resulted in the highest bioaccessibility levels among all household procedures. Discarding the soaking water before cooking did not improve the nutritional quality of the beans.

Changes of serum trace elements in early stage trauma and its correlation with injury severity score

BACKGROUND

Severe trauma can cause secondary multiple organ dysfunction syndrome and death. The absolute and relative concentrations of trace elements in both critical care and conventional treatment, which can lead to acute trace element deficiency, constitute an important mechanism of multiple organ dysfunction syndrome (MODS)/multiple organ failure (MOF).

METHODS

We investigated the changes in serum Cu, Zn, and Fe in early stage trauma of patients with the high injury severity score (ISS) and correlated the change in trace elements with ISS. Blood samples were collected within an hour of admittance and the patients were scored according to ISS. We collected clinical data records and ISS score values, and determined serum Fe, Zn, and Cu by inductively coupled plasma mass spectrometry.

RESULTS

Compared with the control group, the serum Zn and Fe values of trauma patients were decreased. There was no significant difference in serum Cu between the patients and the control group. In the trauma group, the serum Zn and Fe were lower than that of the minor injury group, and the difference of Cu concentration was not statistically significant.

CONCLUSIONS

Serum Zn and Fe levels in patients with multiple trauma fractures were significantly different than those in the normal group, suggesting that Zn and Fe need to be monitored in the early stage of trauma.

Invited review: Mineral absorption mechanisms, mineral interactions that affect acid-base and antioxidant status, and diet considerations to improve mineral status

Several minerals are required for life to exist. In animals, 7 elements (Ca, P, Mg, Na, K, Cl, and S) are required to be present in the diet in fairly large amounts (grams to tens of grams each day for the dairy cow) and are termed macrominerals. Several other elements are termed microminerals or trace minerals because they are required in much smaller amounts (milligrams to micrograms each day). In most cases the mineral in the diet must be absorbed across the gastrointestinal mucosa and enter the blood if it is to be of value to the animal. The bulk of this review discusses the paracellular and transcellular mechanisms used by the gastrointestinal tract to absorb each of the various minerals needed. Unfortunately, particularly in ruminants, interactions between minerals and other substances within the diet can occur within the digestive tract that impair mineral absorption. The attributes of organic or chelated minerals that might permit diet minerals to circumvent factors that inhibit absorption of more traditional inorganic forms of these minerals are discussed. Once absorbed, minerals are used in many ways. One focus of this review is the effect macrominerals have on the acid-base status of the animal. Manipulation of dietary cation and anion content is commonly used as a tool in the dry period and during lactation to improve performance. A section on how the strong ion theory can be used to understand these effects is included. Many microminerals play a role in the body as cofactors of enzymes involved in controlling free radicals within the body and are vital to antioxidant capabilities. Those same minerals, when consumed in excess, can become pro-oxidants in the body, generating destructive free radicals. Complex interactions between minerals can compromise the effectiveness of a diet in promoting health and productivity of the cow. The objective of this review is to provide insight into some of these mechanisms.

Sugarcane Molasses - A Potential Dietary Supplement in the Management of Iron Deficiency Anemia

Iron deficiency anemia (IDA) is a serious public health problem that debilitates ∼1.6 billion people globally every year, the majority being pregnant women and children from developing countries. In India, for example, in spite of several operational programs at the national level using iron-folic acid and other allopathic interventions, IDA is still prevalent. Traditional medicines, such as Ayurveda, prescribe herbal formulations containing sugarcane derivatives for the management of pandu, a condition similar to IDA. This article reviews molasses, a sugar industry by-product, as a potential raw material to develop nutraceutical products for IDA. Molasses contains iron and its absorption enhancers, such as sulfur, fructose, and copper, which make it a potential dietary supplement for IDA. More research, product development, and evidence of safety and efficacy of molasses in IDA management can provide a tasty and cost-effective dietary supplement, particularly for children. However, there are challenges, such as competition for raw material from refined sugar manufacturers, quality control, etc., that need to be overcome.

Mineral nutrient interaction: Improving bioavailability of calcium and iron

Insufficient uptake of essential metals leads to serious malnutrition, which is a worldwide problem. Low bioavailability of iron and calcium may lead to anemia and osteoporosis, respectively, even in individuals with a high dietary intake. For iron, fractionation of meat proteins was studied in order to increase iron bioavailability from other meal components, and uptake of iron was found to increase with minimal risk of increasing oxidative damage. Calcium binding to peptides was found to prevent formation of insoluble calcium salts otherwise hampering absorption particularly in combination with calcium hydroxycarboxylates, entailing spontaneous supersaturation. Based on a review of results from different strategies available for increasing bioavailability, safe iron fortification is suggested to be supported by calcium, with modulation of iron as a prooxidant.

Acute Copper and Ascorbic Acid Supplementation Inhibits Non-heme Iron Absorption in Humans

The objective of the study is to determine the effect of copper (Cu) plus the reducing agent ascorbic acid (AA) on the absorption of non-heme iron (Fe). Experimental study with block design in which each subject was his own control. After signing an informed consent, 14 adult women using an effective method of contraception and negative pregnancy test received 0.5 mg Fe, as ferrous sulfate, alone or with Cu, as copper sulfate, plus ascorbic acid (AA/Cu 2/1 molar ratio) at 4/1; 6/1 and 8/1 Cu/Fe molar ratios as an aqueous solution on days 1, 2, 14, and 15 of the study. Fe absorption was assessed by erythrocyte incorporation of iron radioisotopes (55)Fe and (59)Fe. Geometric mean (range ± SD) absorption of Fe at 4/1 and 6/1 Cu/Fe molar ratios (and AA/Cu 2/1 molar ratio) and Fe alone was 57.4 % (35.7-92.1 %), 64.2 % (45.8-89.9 %), and 38.8 % (20.4-73.8 %), respectively (ANOVA for repeated measures p < 0.001; post hoc test Scheffé, p < 0.05). This is attributable to the enhancing effect of AA on non-heme Fe absorption; however, Fe absorption at Cu/Fe 8/1 molar ratio was 47.3 % (27.7-80.8) (p = NS compared with Fe alone). It was expected that Fe absorption would have been equal or greater than at 4/1 and 6/1 molar ratios. Copper in the presence of ascorbic acid inhibits non-heme Fe absorption at Cu/Fe 8/1 molar ratio.

Mineral nutrient interaction: Improving bioavailability of calcium and iron

Insufficient uptake of essential metals leads to serious malnutrition, which is a worldwide problem. Low bioavailability of iron and calcium may lead to anemia and osteoporosis, respectively, even in individuals with a high dietary intake. For iron, fractionation of meat proteins was studied in order to increase iron bioavailability from other meal components, and uptake of iron was found to increase with minimal risk of increasing oxidative damage. Calcium binding to peptides was found to prevent formation of insoluble calcium salts otherwise hampering absorption particularly in combination with calcium hydroxycarboxylates, entailing spontaneous supersaturation. Based on a review of results from different strategies available for increasing bioavailability, safe iron fortification is suggested to be supported by calcium, with modulation of iron as a prooxidant.

Effect of daily supplementation with iron and zinc on iron status of childbearing age women

The objective was to determine the effect of daily supplementation with 30 mg of iron (Fe) plus 30 mg of zinc (Zn) for 3 months on Fe status of women of childbearing age. This was a randomized double-blind, placebo-controlled trial. Eighty-one women (18-45 years) were randomly assigned to receive either a daily single dose of 30 mg of Fe (group 1; n = 28) and 30 mg of Fe plus 30 mg of Zn (group 2; n = 26) or placebo (n = 27) for 3 months. Hemoglobin (Hb), mean corpuscular volume, serum Fe, total iron-binding capacity, transferrin saturation, erythrocyte Zn protoporphyrin, serum ferritin (SF), serum transferrin receptor (TfR), total body Fe, serum Zn, and high-sensitivity C-reactive protein were measured at baseline and at the end of the study. At baseline, 3.7, 28.4, and 3.7 % of women had iron-deficiency anemia (IDA), Fe deficiency without anemia, and depleted Fe stores, respectively. No significant differences on Fe status were found between groups before supplementation. After supplementation, group 2 showed a significant increase of Hb and total body Fe and a significant decrease of TfR compared with placebo (p < 0.05). Moreover, serum Zn increased significantly in group 2 compared with group 1 (p < 0.01) and placebo (p < 0.01). In conclusion, daily supplementation with 30 mg of Fe plus 30 mg of Zn for 3 months improved significantly the Fe and Zn status of women, compared with those who received placebo. The positive effect of Fe supplementation on Fe status is enhanced by combined Zn supplementation.

Increased iron bioavailability from lactic-fermented vegetables is likely an effect of promoting the formation of ferric iron (Fe(3+))

Background

Lactic fermentation of foods increases the availability of iron as shown in a number of studies throughout the years. Several explanations have been provided such as decreased content of inhibitory phytate, increased solubility of iron, and increased content of lactic acid in the fermented product. However, to our knowledge, there are no data to support that the bioavailability of iron is affected by lactic fermentation.

Objectives

The objective of the present study was to investigate whether the bioavailability of iron from a vegetable mix was affected by lactic fermentation and to propose a mechanism for such an event, by conducting human and cell (Caco-2, HepG2) studies and iron speciation measurements (voltammetry). We also investigated whether the absorption of zinc was affected by the lactic fermentation.

Results

In human subjects, we observed that lactic-fermented vegetables served with both a high-phytate and low-phytate meal increased the absorption of iron, but not zinc. In vitro digested fermented vegetables were able to provoke a greater hepcidin response per ng Fe than fresh vegetables, indicating that Fe in the fermented mixes was more bioavailable, independent on the soluble Fe content. We measured that hydrated Fe³⁺ species were increased after the lactic fermentation, while there was no significant change in hydrated Fe²⁺. Furthermore, lactate addition to Caco-2 cells did not affect ferritin formation in response to Fe nor did lactate affect the hepcidin response in the Caco-2/HepG2 cell system.

Conclusions

The mechanism for the increased bioavailability of iron from lactic-fermented vegetables is likely an effect of the increase in ferric iron (Fe³⁺) species caused by the lactic fermentation. No effect on zinc bioavailability was observed.

Proposing a Caco-2/HepG2 cell model for in vitro iron absorption studies

The Caco-2 cell line is well established as an in vitro model for iron absorption. However, the model does not reflect the regulation of iron absorption by hepcidin produced in the liver. We aimed to develop the Caco-2 model by introducing human liver cells (HepG2) to Caco-2 cells. The Caco-2 and HepG2 epithelia were separated by a liquid compartment, which allowed for epithelial interaction. Ferritin levels in cocultured Caco-2 controls were 21.7±10.3 ng/mg protein compared to 7.7±5.8 ng/mg protein in monocultured Caco-2 cells. The iron transport across Caco-2 layers was increased when liver cells were present (8.1%±1.5% compared to 3.5%±2.5% at 120 μM Fe). Caco-2 cells were exposed to 0, 80 and 120 μM Fe and responded with increased hepcidin production at 120 μM Fe (3.6±0.3 ng/ml compared to 2.7±0.3 ng/ml). The expression of iron exporter ferroportin in Caco-2 cells was decreased at the hepcidin concentration of 3.6 ng/ml and undetectable at external addition of hepcidin (10 ng/ml). The apical transporter DMT1 was also undetectable at 10 ng/ml but was unchanged at the lower concentrations. In addition, we observed that sourdough bread, in comparison to heat-treated bread, increased the bioavailability of iron despite similar iron content (53% increase in ferritin formation, 97% increase in hepcidin release). This effect was not observed in monocultured Caco-2 cells. The Caco-2/HepG2 model provides an alternative approach to in vitro iron absorption studies in which the hepatic regulation of iron transport must be considered.

Iron transport through ferroportin is induced by intracellular ascorbate and involves IRP2 and HIF2α

A few tightly regulated transport proteins mediate iron absorption across the intestinal epithelium. At the basolateral border of intestinal cells there is one identified transporter, ferroportin, for the transfer of intracellular iron to the vascular system. Here, we investigate the effects of ascorbate (vitamin C) on the regulation of ferroportin in human intestinal Caco-2 cells using ELISA and Western Blot analyses. The results indicate that ferroportin protein levels peak at 100 μM of added ascorbate with an increase of 274% (p = 0.02). At 150 μM of ascorbate, the increase was only 28% (p = 0.04), and at 200 μM there was no significant change from the baseline control. In addition, the ascorbate-induced, (at 150 μM) up-regulated ferroportin levels were associated with increased ⁵⁵Fe transport across the basolateral border (19%, p = 0.03). Ascorbate-induced up-regulation of cellular ferroportin levels (no added iron) was associated with increased levels of the iron regulatory protein IRP2 (230%, p = 0.0009), and the hypoxia-inducible factor HIF2α (69%, p = 0.03). Thus, iron transport across the basal border via ferroportin is influenced by the intracellular status of ascorbate and IRP2 and HIF2α are involved. We discuss possible reasons for the ascorbate-effects and the dependence of cellular growth conditions for iron transport-related protein expression.

Multi-copper oxidases and human iron metabolism

Multi-copper oxidases (MCOs) are a small group of enzymes that oxidize their substrate with the concomitant reduction of dioxygen to two water molecules. Generally, multi-copper oxidases are promiscuous with regards to their reducing substrates and are capable of performing various functions in different species. To date, three multi-copper oxidases have been detected in humans—ceruloplasmin, hephaestin and zyklopen. Each of these enzymes has a high specificity towards iron with the resulting ferroxidase activity being associated with ferroportin, the only known iron exporter protein in humans. Ferroportin exports iron as Fe²⁺, but transferrin, the major iron transporter protein of blood, can bind only Fe³⁺ effectively. Iron oxidation in enterocytes is mediated mainly by hephaestin thus allowing dietary iron to enter the bloodstream. Zyklopen is involved in iron efflux from placental trophoblasts during iron transfer from mother to fetus. Release of iron from the liver relies on ferroportin and the ferroxidase activity of ceruloplasmin which is found in blood in a soluble form. Ceruloplasmin, hephaestin and zyklopen show distinctive expression patterns and have unique mechanisms for regulating their expression. These features of human multi-copper ferroxidases can serve as a basis for the precise control of iron efflux in different tissues. In this manuscript, we review the biochemical and biological properties of the three human MCOs and discuss their potential roles in human iron homeostasis.