Importance of iron absorption in human health: An overview

Author(s):  
Satya Prasad Dixit ◽  
Logesh Rajan ◽  
Dhanabal Palaniswamy ◽  
Suresh Kumar Mohankumar

: Iron is one of the essential elements required for human health, as it plays a vital role in a number of metabolic, growth and developmental processes, including erythropoiesis, DNA synthesis, electron transport and others. Iron deficiency is a concern in both developing and developed (industrialized) countries, and in particular young women are highly vulnerable. This review investigates dietary and genetic determinants of iron metabolism in the human body and a possible solution to combat the iron deficiency by exploring via various targets. Hence, this review mainly focuses on the assessment of dietary and genetic factors affecting the iron bioavailability and homeostasis and collates the available information from 2000 to till date from Pubmed. The dietary factors including ascorbic acid an important factor in animal protein foods (meat, fish and poultry) enhance iron absorption whereas the phytic acid, soy protein, calcium and polyphenols have been reported to inhibit iron absorption. However, the effects of these dietary factors on iron absorption do not necessarily translate into an association with iron status and iron stores (serum ferritin concentration). Moreover, the genetic factors influence the absorption of iron involving HFE, TFR2, FPN1 and HAMP in humans. Further research is needed to determine optimal dietary recommendations for both the prevention and treatment of iron deficiency.

2001 ◽  
Vol 4 (2b) ◽  
pp. 537-545 ◽  
Author(s):  
Serge Hercberg ◽  
Paul Preziosi ◽  
Pilar Galan

AbstractIn Europe, iron deficiency is considered to be one of the main nutritional deficiency disorders affecting large fractions of the population, particularly such physiological groups as children, menstruating women and pregnant women. Some factors such as type of contraception in women, blood donation or minor pathological blood loss (haemorrhoids, gynaecological bleeding,..) considerably increase the difficulty of covering iron needs. Moreover, women, especially adolescents consuming lowenergy diets, vegetarians and vegans are at high risk of iron deficiency.Although there is no evidence that an anbsence of iron stores has any adverse consequences, it does indicate that iron nutrition is borderline, since any further reduction in body iron is associated with a decrease in the level of functional compounds such as haemoglobin.The prevalence of iron-deficient anaemia has slightly decreased in infants and menstruating women. Some positive factors may have contributed to reducing the prevalence of iron-deficiency anaemia in some groups of population: the use of iron-frotified formulas and iron-fortified cereals; the use of oral contraceptives and increased enrichment of iron in several countries; and the use of iron supplements during pregnancy in some European countries.It is possible to prevent and control iron deficiency by counseling individuals and families about sound iron nutrition during infancy and beyond, and about iron supplementation during pregnancy, by screening persons on the basis of their risk for iron deficiency, and by treating and following up persons with presumptive iron deficiency. This may help to reduce manifestations of iron deficiency and thus improve public health. Evidence linking iron status with risk of cardiovascular disease or cancer is unconvincing and does not justify changes in food fortification or medical practice, particularly because the benefits of assuring adequate iron intake during growth and development are well established. But stronger evidence is needed before rejecting the hypothesis that greater iron stores increase the incidence of CVD or cancer. At present, currently available data do not support radical changes in dietary recommendations. They include all means for increasing the content of dietary factors enhancing iron absorption or reducing the content of factors inhibiting iron absorption. Increased knowledge and increased information about factors may be important tools in the prevention of iron deficiency in Europe.


2010 ◽  
Vol 80 (45) ◽  
pp. 257-262 ◽  
Author(s):  
Janet R. Hunt

Several bioavailability algorithms have been proposed for iron and zinc, confirming the need for these tools while emphasizing the challenge of deriving algorithms with accepted accuracy. This manuscript briefly reviews current evidence on the accuracy of proposed algorithms. Iron absorption is strongly influenced by both body iron status and dietary availability, and most evidence suggests that these do not interact. There is considerable evidence of a logarithmic relationship between percent iron absorption and serum ferritin that allows a simple and accurate computation of how human iron status affects absorption (in the absence of inflammation). Computing the effect of dietary variation on nonheme iron absorption has been challenging because of multiple influential dietary factors and incomplete knowledge of their chemical characteristics, food composition, interactions, and dose-response relationships. At present there is no fully validated algorithm for dietary iron bioavailability. Predicting zinc absorption is less complex. Fractional zinc absorption is substantially influenced by the amount of zinc consumed, and this factor, together with ingested phytic acid, account for a considerable degree of the variance. A multivariate saturation model based on these two variables has been derived using data from multiple studies and independently validated with a single large data set.


2005 ◽  
Vol 75 (6) ◽  
pp. 405-412 ◽  
Author(s):  
Manju B. Reddy

While sufficient information exists on the effect of individual factors on iron absorption, their net effect in a mixed meal is less well characterized, being dependent on the combination and quantity of the factors present in the meal. Over a period of more than 25 years, several models have been developed to estimate non-heme iron bioavailability, either to assess iron absorption from a meal or iron sufficiency in populations. Initially, a model was developed to calculate iron absorption in individuals with varying iron status that included only enhancers. This model was useful in classifying the diets but has limited value for accurale assessment. Later models were modified and improved by including inhibitors in the calculations. However, some included either phytate or tea but not in combination. The models that included all the factors in calculations assumed their effect was independent and additive rather than interactive, which is an important issue in addressing iron bioavailability. Although some of the models correlated estimated bioavailability with iron status of the population, the accuracy of the estimations is of concern due to lack of quantitative measurements of bioavailability modifiers, inability to consider interactive effects, and the use of non-iron status measurements. Recent research has led to the development of refined models to assess iron bioavailability of complex meals by comprehensively taking into consideration the interactive effect among enhancers and inhibitors. However, the models are based on single-meal studies and their application to whole diets at a population level is not clear. Accurate measurements of dietary factors and independent validation are needed before using these models. To date, no single model is applicable to all diets and additional studies are needed to develop new models to predict bioavailability of whole diets accurately, in addition to addressing dietary adequacy in all populations.


2005 ◽  
Vol 75 (6) ◽  
pp. 375-384 ◽  
Author(s):  
Janet R. Hunt

Iron deficiency, a global health problem, impairs reproductive performance, cognitive development, and work capacity. One proposed strategy to address this problem is the improvement of dietary iron bioavailability. Knowledge of the molecular mechanisms of iron absorption is growing rapidly, with identification of mucosal iron transport and regulatory proteins. Both body iron status and dietary characteristics substantially influence iron absorption, with minimal interaction between these two factors. Iron availability can be regarded mainly as a characteristic of the diet, but comparisons between human studies of iron availability for absorption require normalization for the iron status of the subjects. The dietary characteristics that enhance or inhibit iron absorption from foods have been sensitively and quantitatively determined in human studies employing iron isotopes. People with low iron status can substantially increase their iron absorption from diets with moderate to high availability. But while iron supplementation and fortification trials can effectively increase blood indices of iron status, improvements in dietary availability alone have had minimal influence on such indices within several weeks or months. Plentiful, varied diets are the ultimate resolution to iron deficiency. Without these, more modest food-based approaches to human iron deficiency likely will need to be augmented by dietary iron fortification.


2018 ◽  
Vol 108 (6) ◽  
pp. 1324-1333 ◽  
Author(s):  
Diego Moretti ◽  
Samuel Mettler ◽  
Christophe Zeder ◽  
Carsten Lundby ◽  
Anneke Geurts-Moetspot ◽  
...  

ABSTRACT Background Iron status is a determinant of physical performance, but training may induce both low-grade inflammation and erythropoiesis, exerting opposing influences on hepcidin and iron metabolism. To our knowledge, the combined effects on iron absorption and utilization during training have not been examined directly in humans. Objective We hypothesized that 3 wk of exercise training in recreational male runners would decrease oral iron bioavailability by increasing inflammation and hepcidin concentrations. Design In a prospective intervention, nonanemic, iron-sufficient men (n = 10) completed a 34-d study consisting of a 16-d control phase and a 22-d exercise-training phase of 8 km running every second day. We measured oral iron absorption and erythroid iron utilization using oral 57Fe and intravenous 58Fe tracers administered before and during training. We measured hemoglobin mass (mHb) and total red blood cell volume (RCV) by carbon monoxide rebreathing. Iron status, interleukin-6 (IL-6), plasma hepcidin (PHep), erythropoietin (EPO), and erythroferrone were measured before, during, and after training. Results Exercise training induced inflammation, as indicated by an increased mean ± SD IL-6 (0.87 ± 1.1 to 5.17 ± 2.2 pg/mL; P < 0.01), while also enhancing erythropoiesis, as indicated by an increase in mean EPO (0.66 ± 0.42 to 2.06 ± 1.6 IU/L), mHb (10.5 ± 1.6 to 10.8 ± 1.8 g/kg body weight), and mean RCV (30.7 ± 4.3 to 32.7 ± 4.6 mL/kg) (all P < 0.05). Training tended to increase geometric mean iron absorption by 24% (P = 0.083), consistent with a decreased mean ± SD PHep (7.25 ± 2.14 to 5.17 ± 2.24 nM; P < 0.05). The increase in mHb and erythroid iron utilization were associated with the decrease in PHep (P < 0.05). Compartmental modeling indicated that iron for the increase in mHb was obtained predominantly (>80%) from stores mobilization rather than from increased dietary absorption. Conclusions In iron-sufficient men, mild intensification of exercise intensity increases both inflammation and erythropoiesis. The net effect is to decrease hepcidin concentrations and to tend to increase oral iron absorption. This trial was registered at clinicaltrials.gov as NCT01730521.


PLoS ONE ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. e0250759
Author(s):  
Abdelhamid Kerkadi ◽  
Reem Mohsen Ali ◽  
Alaa A. H. Shehada ◽  
Eman Abdelnasser AbouHassanein ◽  
Joyce Moawad ◽  
...  

Co-existence of iron deficiency and obesity in adults has been reported in many countries. However, little is known on the association between obesity and iron deficiency in Qatar. This study aimed to investigate the link between abdominal obesity indices and iron status among adults in Qatar. A random sample of 1000 healthy Qatari adults, aged 20–50 years, was obtained from Qatar Biobank study. Body weight, waist circumference, dual x-ray absorptiometry (DXA) parameters and iron status indicators were measured using standard techniques. Multiple regression analysis was used to examine the associations. The prevalence of iron deficiency and anaemia were 35.4 and 25%, respectively. Of the participants with a large waist circumference, 31.7% had anaemia. Ferritin significantly increased with the increase in the android fat to gynoid fat ratio and visceral fat in both genders. Serum iron and transferring saturation decreased significantly with the increase in waist circumference in women. In both genders, C-reactive protein increased with the increase in all obesity indices. Standardized values of waist circumference, android fat, gynoid fat ratio and visceral fat were significantly associated with log transformed ferritin in men and women. Waist circumference was inversely related to serum iron (β:-0.95, 95% CI:-1.50,-0.39) and transferrin saturation (β:-1.45, 95%CI:-2.46, -0.43) in women. In men, waist circumference was positively associated with haemoglobin level (β: 0.16, 95% CI:0.04, 0.29). Central obesity coexists with anaemia among the study population. Elevated central obesity indices were associated with an increase in ferritin concentration. The increased ferritin concentration may be attributed to the increase in inflammatory status as a result of an increase in c-reactive protein concentration associated with central obesity.


2004 ◽  
Vol 74 (6) ◽  
pp. 435-443 ◽  
Author(s):  
Hertrampf ◽  
Olivares

Iron amino acid chelates, such as iron glycinate chelates, have been developed to be used as food fortificants and therapeutic agents in the prevention and treatment of iron deficiency anemia. Ferrous bis-glycine chelate (FeBC), ferric tris-glycine chelate, ferric glycinate, and ferrous bis-glycinate hydrochloride are available commercially. FeBC is the most studied and used form. Iron absorption from FeBC is affected by enhancers and inhibitors of iron absorption, but to a lesser extent than ferrous sulfate. Its absorption is regulated by iron stores. FeBC is better absorbed from milk, wheat, whole maize flour, and precooked corn flour than is ferrous sulfate. Supplementation trials have demonstrated that FeBC is efficacious in treating iron deficiency anemia. Consumption of FeBC-fortified liquid milk, dairy products, wheat rolls, and multi-nutrient beverages is associated with an improvement of iron status. The main limitations to the widespread use of FeBC in national fortification programs are the cost and the potential for promoting organoleptic changes in some food matrices. Additional research is required to establish the bioavailability of FeBC in different food matrices. Other amino acid chelates should also be evaluated. Finally there is an urgent need for more rigorous efficacy trials designed to define the relative merits of amino acid chelates when compared with bioavailable iron salts such as ferrous sulfate and ferrous fumarate and to determine appropriate fortification levels


Blood ◽  
1989 ◽  
Vol 74 (6) ◽  
pp. 2187-2193 ◽  
Author(s):  
SR Lynch ◽  
BS Skikne ◽  
JD Cook

Abstract The relationship between iron status and food iron absorption was evaluated in 75 normal volunteers, 15 patients with idiopathic hemochromatosis, and 22 heterozygotes by using double extrinsic radioiron tags to label independently the nonheme and heme iron components of a hamburger meal. In normal subjects, absorption from each of these pools was inversely correlated with storage iron, as measured by the serum ferritin concentration. In patients with hemochromatosis, absorption of both forms of iron was far greater than would be predicted from the relationship between absorption and serum ferritin observed in normal volunteers. Nevertheless, there was still a modest but statistically significant reduction in absorption of nonheme iron with increasing serum ferritin. This relationship could not be demonstrated in the case of heme iron absorption. In heterozygotes, nonheme iron absorption from a hamburger meal containing no supplementary iron did not differ significantly from that observed in normal volunteers. However, when this meal was both modified to promote bioavailability and supplemented with iron, absorption of nonheme iron was significantly elevated. These studies confirm the presence of excessive nonheme iron absorption even from unfortified meals in patients with idiopathic hemochromatosis and suggest in addition that they are particularly susceptible to iron loading from diets containing a high proportion of heme iron. Impaired regulation of nonheme iron absorption was also observed in heterozygous individuals, but a statistically significant abnormality was demonstrable only when the test meal contained a large highly bioavailable iron supplement.


2019 ◽  
Vol 3 (10) ◽  
Author(s):  
Amanda S Wendt ◽  
Jillian L Waid ◽  
Sabine Gabrysch

ABSTRACT Background Anemia affects ∼1.6 billion people worldwide, often owing to iron deficiency. In Bangladesh, high levels of anemia have been observed alongside little iron deficiency. Elevated concentrations of groundwater iron could constitute a significant source of dietary iron. Objective We aimed to quantify the effect of groundwater iron on anemia in nonpregnant women and young children in Bangladesh, taking into account dietary factors that may affect iron absorption. Methods We analyzed data on 1871 nonpregnant women and 987 children (6–37 mo) from the 2015 baseline survey of the Food and Agricultural Approaches to Reducing Malnutrition cluster-randomized trial in Sylhet, Bangladesh. We used logistic regression with robust standard errors to assess effects of self-reported groundwater iron, dietary intake, and sociodemographic characteristics on anemia, considering interactions between groundwater iron and dietary factors. Results Groundwater iron presence was associated with less anemia in women (OR: 0.74; 95% CI: 0.60, 0.90) and children (OR: 0.58; 95% CI: 0.44, 0.76). This effect was modified by dietary factors. In women, the effect of groundwater iron on anemia was stronger if no vitamin C–rich or heme-iron foods were consumed, and there was a clear dose–response relation. In children, intake of vitamin C–rich foods strengthened the effect of groundwater iron on anemia, and there was no evidence for interaction by intake of iron-rich foods. Conclusions Heme-iron and vitamin C consumption reduced the effect of groundwater iron on anemia among women but not children in Bangladesh, which may be due to higher levels of iron deficiency and lower levels of iron intake among children. Vitamin C consumption appears to enhance iron absorption from groundwater in children and they may thus benefit from consuming more vitamin C–rich fruits and vegetables. Even among women and children consuming heme-iron or vitamin C–rich foods and groundwater iron, anemia prevalence remained elevated, pointing to additional causes of anemia beyond iron deficiency. This trial was registered at clinicaltrials.gov as NCT02505711.


2010 ◽  
Vol 82 (2) ◽  
pp. 429-436 ◽  
Author(s):  
Bo Lönnerdal

Iron is known to be absorbed from foods in two major forms, heme iron and non-heme iron. Iron status as well as dietary factors known to affect iron absorption has limited effect on heme iron absorption, whereas inhibitors and enhancers of iron absorption have pronounced effects on non-heme iron absorption. The enterocyte transporter for non-heme iron, DMT1, is strongly up-regulated during iron deficiency and down-regulated during iron overload. A transporter for heme iron, HCP1, was recently characterized and is present on the apical membrane of enterocytes. Two other pathways for iron absorption have been discovered and may serve to facilitate uptake of iron from two unique iron-binding proteins, lactoferrin and ferritin. Lactoferrin is an iron-binding protein in human milk and known to survive proteolytic digestion. It mediates iron uptake in breast-fed infants through endocytosis via a specific lactoferrin receptor (LfR). Recently, lactoferrin has become popular as a food additive and may enhance iron status in several age groups. Ferritin is present in meat, but also in plants. The ferritin content of plants can be enhanced by conventional breeding or genetic engineering, and thereby increase iron intake of populations consuming plant-based diets. Ferritin is a bioavailable source of iron, as shown in recent human studies. Ferritin can be taken up by intestinal cells via endocytosis, suggesting a receptor-mediated mechanism.


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