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Cell Jan 2017200 billion red blood cells (RBCs) are produced every day, requiring more than 2 × 10 iron atoms every second to maintain adequate erythropoiesis. These numbers... (Review)
Review
200 billion red blood cells (RBCs) are produced every day, requiring more than 2 × 10 iron atoms every second to maintain adequate erythropoiesis. These numbers translate into 20 mL of blood being produced each day, containing 6 g of hemoglobin and 20 mg of iron. These impressive numbers illustrate why the making and breaking of RBCs is at the heart of iron physiology, providing an ideal context to discuss recent progress in understanding the systemic and cellular mechanisms that underlie the regulation of iron homeostasis and its disorders.
Topics: Anemia; Animals; Biological Transport; Erythroid Cells; Erythropoiesis; Hepcidins; Humans; Inflammation; Iron; Iron, Dietary
PubMed: 28129536
DOI: 10.1016/j.cell.2016.12.034 -
European Journal of Sport Science Mar 2018Maintaining a positive iron balance is essential for female athletes to avoid the effects of iron deficiency and anaemia and to maintain or improve performance. A major... (Review)
Review
Maintaining a positive iron balance is essential for female athletes to avoid the effects of iron deficiency and anaemia and to maintain or improve performance. A major function of iron is in the production of the oxygen and carbon dioxide carrying molecule, haemoglobin, via erythropoiesis. Iron balance is under the control of a number of factors including the peptide hormone hepcidin, dietary iron intake and absorption, environmental stressors (e.g. altitude), exercise, menstrual blood loss and genetics. Menstruating females, particularly those with heavy menstrual bleeding are at an elevated risk of iron deficiency. Haemoglobin concentration [Hb] and serum ferritin (sFer) are traditionally used to identify iron deficiency, however, in isolation these may have limited value in athletes due to: (1) the effects of fluctuations in plasma volume in response to training or the environment on [Hb], (2) the influence of inflammation on sFer and (3) the absence of sport, gender and individually specific normative data. A more detailed and longitudinal examination of haematology, menstrual cycle pattern, biochemistry, exercise physiology, environmental factors and training load can offer a superior characterisation of iron status and help to direct appropriate interventions that will avoid iron deficiency or iron overload. Supplementation is often required in iron deficiency; however, nutritional strategies to increase iron intake, rest and descent from altitude can also be effective and will help to prevent future iron deficient episodes. In severe cases or where there is a time-critical need, such as major championships, iron injections may be appropriate.
Topics: Athletes; Athletic Performance; Dietary Supplements; Exercise; Female; Hemoglobins; Humans; Iron Deficiencies; Iron, Dietary; Menstruation; Nutritional Requirements; Sports Nutritional Physiological Phenomena
PubMed: 29280410
DOI: 10.1080/17461391.2017.1416178 -
The American Journal of Clinical... May 2010Iron differs from other minerals because iron balance in the human body is regulated by absorption only because there is no physiologic mechanism for excretion. On the...
Iron differs from other minerals because iron balance in the human body is regulated by absorption only because there is no physiologic mechanism for excretion. On the basis of intake data and isotope studies, iron bioavailability has been estimated to be in the range of 14-18% for mixed diets and 5-12% for vegetarian diets in subjects with no iron stores, and these values have been used to generate dietary reference values for all population groups. Dietary factors that influence iron absorption, such as phytate, polyphenols, calcium, ascorbic acid, and muscle tissue, have been shown repeatedly to influence iron absorption in single-meal isotope studies, whereas in multimeal studies with a varied diet and multiple inhibitors and enhancers, the effect of single components has been, as expected, more modest. The importance of fortification iron and food additives such as erythorbic acid on iron bioavailability from a mixed diet needs clarification. The influence of vitamin A, carotenoids, and nondigestible carbohydrates on iron absorption and the nature of the "meat factor" remain unresolved. The iron status of the individual and other host factors, such as obesity, play a key role in iron bioavailability, and iron status generally has a greater effect than diet composition. It would therefore be timely to develop a range of iron bioavailability factors based not only on diet composition but also on subject characteristics, such as iron status and prevalence of obesity.
Topics: 6-Phytase; Animals; Biological Availability; Calcium; Diet; Dietary Proteins; Flavonoids; Food, Fortified; Hemochromatosis; Humans; Intestinal Absorption; Iron Overload; Iron, Dietary; Milk Proteins; National Academies of Science, Engineering, and Medicine, U.S., Health and Medicine Division; Phenols; Phytic Acid; Polyphenols; Reference Values; United States
PubMed: 20200263
DOI: 10.3945/ajcn.2010.28674F -
Journal of Pediatric Gastroenterology... Jan 2017This position paper considers different aspects of complementary feeding (CF), focussing on healthy term infants in Europe. After reviewing current knowledge and... (Review)
Review
UNLABELLED
This position paper considers different aspects of complementary feeding (CF), focussing on healthy term infants in Europe. After reviewing current knowledge and practices, we have formulated these recommendations: Timing: Exclusive or full breast-feeding should be promoted for at least 4 months (17 weeks, beginning of the 5th month of life) and exclusive or predominant breast-feeding for approximately 6 months (26 weeks, beginning of the 7th month) is a desirable goal. Complementary foods (solids and liquids other than breast milk or infant formula) should not be introduced before 4 months but should not be delayed beyond 6 months.
CONTENT
Infants should be offered foods with a variety of flavours and textures including bitter tasting green vegetables. Continued breast-feeding is recommended alongside CF. Whole cows' milk should not be used as the main drink before 12 months of age. Allergenic foods may be introduced when CF is commenced any time after 4 months. Infants at high risk of peanut allergy (those with severe eczema, egg allergy, or both) should have peanut introduced between 4 and 11 months, following evaluation by an appropriately trained specialist. Gluten may be introduced between 4 and 12 months, but consumption of large quantities should be avoided during the first weeks after gluten introduction and later during infancy. All infants should receive iron-rich CF including meat products and/or iron-fortified foods. No sugar or salt should be added to CF and fruit juices or sugar-sweetened beverages should be avoided. Vegan diets should only be used under appropriate medical or dietetic supervision and parents should understand the serious consequences of failing to follow advice regarding supplementation of the diet.
METHOD
Parents should be encouraged to respond to their infant's hunger and satiety queues and to avoid feeding to comfort or as a reward.
Topics: Animals; Breast Feeding; Diet; Dietary Sugars; Dietary Supplements; Europe; Feeding Behavior; Female; Food Hypersensitivity; Food, Fortified; Glutens; Guidelines as Topic; Humans; Infant; Infant Formula; Infant Nutritional Physiological Phenomena; Iron, Dietary; Male; Milk; Nutritional Requirements; Nutritional Sciences; Parenting; Pediatrics; Societies
PubMed: 28027215
DOI: 10.1097/MPG.0000000000001454 -
Blood Oct 2015Iron supplements acutely increase hepcidin, but the duration and magnitude of the increase, its dose dependence, and its effects on subsequent iron absorption have not... (Comparative Study)
Comparative Study Randomized Controlled Trial
Iron supplements acutely increase hepcidin, but the duration and magnitude of the increase, its dose dependence, and its effects on subsequent iron absorption have not been characterized in humans. Better understanding of these phenomena might improve oral iron dosing schedules. We investigated whether the acute iron-induced increase in hepcidin influences iron absorption of successive daily iron doses and twice-daily iron doses. We recruited 54 nonanemic young women with plasma ferritin ≤20 µg/L and conducted: (1) a dose-finding investigation with 40-, 60-, 80-, 160-, and 240-mg labeled Fe as [(57)Fe]-, [(58)Fe]-, or [(54)Fe]-FeSO4 given at 8:00 am fasting on 1 or on 2 consecutive days (study 1, n = 25; study 2, n = 16); and (2) a study giving three 60-mg Fe doses (twice-daily dosing) within 24 hours (study 3, n = 13). In studies 1 and 2, 24 hours after doses ≥60 mg, serum hepcidin was increased (P < .01) and fractional iron absorption was decreased by 35% to 45% (P < .01). With increasing dose, fractional absorption decreased (P < .001), whereas absolute absorption increased (P < .001). A sixfold increase in iron dose (40-240 mg) resulted in only a threefold increase in iron absorbed (6.7-18.1 mg). In study 3, total iron absorbed from 3 doses (2 mornings and an afternoon) was not significantly greater than that from 2 morning doses. Providing lower dosages (40-80 mg Fe) and avoiding twice-daily dosing maximize fractional absorption. The duration of the hepcidin response supports alternate day supplementation, but longer-term effects of these schedules require further investigation. These clinical trials were registered at www.ClinicalTrials.gov as #NCT01785407 and #NCT02050932.
Topics: Administration, Oral; Adolescent; Adult; Biological Availability; Biomarkers; Case-Control Studies; Cross-Over Studies; Dietary Supplements; Drug Administration Schedule; Female; Ferritins; Follow-Up Studies; Hepcidins; Humans; Intestinal Absorption; Iron; Iron, Dietary; Male; Middle Aged; Prognosis; Young Adult
PubMed: 26289639
DOI: 10.1182/blood-2015-05-642223 -
Nutrients May 2022Dancers are an athlete population at high risk of developing iron deficiency (ID). The aesthetic nature of the discipline means dancers potentially utilise dietary... (Review)
Review
Dancers are an athlete population at high risk of developing iron deficiency (ID). The aesthetic nature of the discipline means dancers potentially utilise dietary restriction to meet physique goals. In combination with high training demands, this means dancers are susceptible to problems related to low energy availability (LEA), which impacts nutrient intake. In the presence of LEA, ID is common because of a reduced mineral content within the low energy diet. Left untreated, ID becomes an issue that results in fatigue, reduced aerobic work capacity, and ultimately, iron deficient anaemia (IDA). Such progression can be detrimental to a dancer's capacity given the physically demanding nature of training, rehearsal, and performances. Previous literature has focused on the manifestation and treatment of ID primarily in the context of endurance athletes; however, a dance-specific context addressing the interplay between dance training and performance, LEA and ID is essential for practitioners working in this space. By consolidating findings from identified studies of dancers and other relevant athlete groups, this review explores causal factors of ID and potential treatment strategies for dancers to optimise absorption from an oral iron supplementation regime to adequately support health and performance.
Topics: Athletes; Dancing; Energy Intake; Humans; Iron; Iron, Dietary
PubMed: 35565904
DOI: 10.3390/nu14091936 -
The Journal of Nutrition Feb 2021This introductory article provides an in-depth technical background for iron fortification, and thus introduces a series of articles in this supplement designed to...
This introductory article provides an in-depth technical background for iron fortification, and thus introduces a series of articles in this supplement designed to present the current evidence on the fortification of salt with both iodine and iron, that is, double-fortified salt (DFS). This article reviews our current knowledge of the causes and consequences of iron deficiency and anemia and then, with the aim of assisting the comparison between DFS and other common iron-fortified staple foods, discusses the factors influencing the efficacy of iron-fortified foods. This includes the dietary and physiological factors influencing iron absorption; the choice of an iron compound and the fortification technology that will ensure the necessary iron absorption with no sensory changes; encapsulation of iron fortification compounds to prevent unacceptable sensory changes; the addition of iron absorption enhancers; the estimation of the iron fortification level for each vehicle based on iron requirements and consumption patterns; and the iron status biomarkers that are needed to demonstrate improved iron status in populations regularly consuming the iron-fortified food. The supplement is designed to provide a summary of evidence to date that can help advise policy makers considering DFS as an intervention to address the difficult public health issue of iron deficiency anemia, while at the same time using DFS to target iodine deficiency.
Topics: Absorption, Physiological; Anemia, Iron-Deficiency; Biological Availability; Biomarkers; Food Technology; Food, Fortified; Humans; Iodine; Iron Compounds; Iron, Dietary; Nutritional Status; Sodium Chloride, Dietary
PubMed: 33582781
DOI: 10.1093/jn/nxaa175 -
The American Journal of Clinical... Dec 2017During pregnancy, iron needs to increase substantially to support fetoplacental development and maternal adaptation to pregnancy. To meet these iron requirements, both... (Review)
Review
During pregnancy, iron needs to increase substantially to support fetoplacental development and maternal adaptation to pregnancy. To meet these iron requirements, both dietary iron absorption and the mobilization of iron from stores increase, a mechanism that is in large part dependent on the iron-regulatory hormone hepcidin. In healthy human pregnancies, maternal hepcidin concentrations are suppressed in the second and third trimesters, thereby facilitating an increased supply of iron into the circulation. The mechanism of maternal hepcidin suppression in pregnancy is unknown, but hepcidin regulation by the known stimuli (i.e., iron, erythropoietic activity, and inflammation) appears to be preserved during pregnancy. Inappropriately increased maternal hepcidin during pregnancy can compromise the iron availability for placental transfer and impair the efficacy of iron supplementation. The role of fetal hepcidin in the regulation of placental iron transfer still remains to be characterized. This review summarizes the current understanding and addresses the gaps in knowledge about gestational changes in hematologic and iron variables and regulatory aspects of maternal, fetal, and placental iron homeostasis.
Topics: Animals; Dietary Supplements; Female; Fetus; Hepcidins; Homeostasis; Humans; Iron, Dietary; Maternal Nutritional Physiological Phenomena; Maternal-Fetal Exchange; Models, Animal; Nutritional Requirements; Placenta; Pregnancy
PubMed: 29070542
DOI: 10.3945/ajcn.117.155812 -
Gut Microbes 2023Dietary iron intake is closely related to the incidence of colorectal cancer. However, the interactions among dietary iron, gut microbiota, and epithelial cells in...
Dietary iron intake is closely related to the incidence of colorectal cancer. However, the interactions among dietary iron, gut microbiota, and epithelial cells in promoting tumorigenesis have rarely been discussed. Here, we report that gut microbiota plays a crucial role in promoting colorectal tumorigenesis in multiple mice models under excessive dietary iron intake. Gut microbiota modulated by excessive dietary iron are pathogenic, irritating the permeability of the gut barrier and causing leakage of lumen bacteria. Mechanistically, epithelial cells released more secretory leukocyte protease inhibitor (SLPI) to combat the leaked bacteria and limit inflammation. The upregulated SLPI acted as a pro-tumorigenic factor and promoted colorectal tumorigenesis by activating the MAPK signaling pathway. Moreover, excessive dietary iron significantly depleted in the gut microbiota; while supplementation with could successfully attenuate the tumorigenic effect from excessive dietary iron. Overall, excessive dietary iron perturbs diet - microbiome-epithelium interactions, which contributes to intestinal tumor initiation.
Topics: Animals; Mice; Gastrointestinal Microbiome; Iron, Dietary; Secretory Leukocyte Peptidase Inhibitor; Carcinogenesis; Iron; Colorectal Neoplasms
PubMed: 37312410
DOI: 10.1080/19490976.2023.2221978 -
The Journal of Biological Chemistry Aug 2017The regulation of iron metabolism in biological systems centers on providing adequate iron for cellular function while limiting iron toxicity. Because mammals cannot... (Review)
Review
The regulation of iron metabolism in biological systems centers on providing adequate iron for cellular function while limiting iron toxicity. Because mammals cannot excrete iron, mechanisms have evolved to control iron acquisition, storage, and distribution at both systemic and cellular levels. Hepcidin, the master regulator of iron homeostasis, controls iron flows into plasma through inhibition of the only known mammalian cellular iron exporter ferroportin. Hepcidin is feedback-regulated by iron status and strongly modulated by inflammation and erythropoietic demand. This review highlights recent advances that have changed our understanding of iron metabolism and its regulation.
Topics: Animals; Cation Transport Proteins; Erythropoiesis; Hepcidins; Homeostasis; Humans; Immunity, Innate; Intestinal Absorption; Iron; Iron, Dietary; Liver; Macrophages; Models, Biological; Nutritional Status; Paracrine Communication; Receptors, Transferrin; Signal Transduction; Transferrin
PubMed: 28615456
DOI: 10.1074/jbc.R117.781823