Iron Absorption
Intestinal absorption is the main regulator of iron homeostasis. In general, only a small portion of the iron is absorbed from the food, the amount of which varies considerably between individuals and also in the same individual. Increased iron requirement results in increased absorption, which is however limited and rarely exceeds 3–5mg iron / day. Factors such as gastric secretion, pH, bowel motility and gastrointestinal disorders or surgery also affect the iron intake from the diet.13
There are two types of dietary iron:
- Heme iron: which comes from hemoglobin and myoglobin in animal source foods. It has a very good bioavailability, even when it accounts for only a small portion of the dietary iron, and contributes significantly to resorbed iron. 15 to 35% of heme iron is resorbed and its intake is not affected by other food ingredients.14
- Non-heme iron: is found in varying amounts in plant foods. It makes up the bulk of food nourishment (> 90%) and its bioavailability is strongly influenced by the presence of enhancing or inhibiting factors. Iron bioavailability has been estimated to be between 5–12% for vegetarian diets.15
Intestinal Resorption of Heme and Non-heme iron from food
References
- Clénin GE. The treatment of iron deficiency without anaemia (in otherwise healthy persons). Swiss Med Wkly. 2017;147:w14434
- Musallam KM, Taher AT. Iron deficiency beyond erythropoiesis: should we be concerned? Curr Med Res Opin. 2018;34(1):81–93.
- Doom JR. Striking while the iron is hot: Understanding the biological and neurodevelopmental effects of iron deficiency to optimize intervention in early childhood. Curr Pediatr Rep. 2015;2(4):291–298
- Worldwide prevalence of anaemia 1993–2005. WHO The global prevalence of anaemia in 2011. Geneva: World Health Organization 2015
- Lopez A et al. Iron deficiency anaemia. Lancet 2016;387(10021):907–16
- Herklotz R and Huber A. Labordiagnose von Eisenstoffwechselstörungen. Schweiz Med Forum 2010;10(30–31):500–507
- Clénin et al. The treatment of iron deficiency without anaemia (in otherwise healthy persons). Swiss Med Wkly. 2017 Jun14;147:w14434
- Hercberg S, Preziosi P, Galan P. Iron deficiency in Europe. Public Health Nutr 2001; 4: 537–545
- Chrobak C et al. Iron homeostasis in inflammation: a single centre prospective observational study in medical inpatients. Swiss Med Wkly. 2017;147:w14431
- Muckenthaler MU et al. A red carpet for iron metabolism. Cell 2017;168(3):344–361
- Dignass A et al. Limitations of Serum Ferritin in Diagnosing Iron Deficiency in Inflammatory Conditions. Int J Chronic Dis. 2018 Mar 18;2018:9394060
- Crichton RR et al. Iron therapy with special emphasis on intravenous administration. UNI-MED 2008, 4th Edition, chapter 3
- Huch R and Breymann C. Anämie in Schwangerschaft und Wochenbett. UNI-MED 2005, chapt. 3, p. 35
- Hunt JR. High-, but not low-bioavailability diets enable substantial control of women’'s iron absorption in relation to body iron stores, with minimal adaptation within several weeks, The American Journal of Clinical Nutrition, Volume 78, Issue 6, 1 December 2003, Pages 1168–1177
- Hurrell R, Egli I. Iron bioavailability and dietary reference values. Am J Clin Nutr. 2010;91(5):1467S–1467S
- Crichton R et al. Iron Therapy – With Special Emphasis on Intravenous Administration, 4th edition, UNI-MED, 2008, chapt. 2, p. 19–20
- Finch CA, Bellotti V, Stray S, Lipschitz DA, Cook JD, Pippard MJ, Huebers HA. Plasma ferritin determination as a diagnostic tool. West J Med 1986;145:657–663.
- Douglas B. Kell and Etheresia Pretorius. Serum ferritin is an important inflammatory disease marker, as it is mainly a leakage product from damaged cells. Metallomics, 2014,6, 748.
- T. N. Tran, S. K. Eubanks, K. J. Schaffer, C. Y. J. Zhou and M. C. Linder, Secretion of ferritin by rat hepatoma cells and its regulation by inflammatory cytokines and iron, Blood, 1997, 90, 4979–4986.
- L. A. Cohen, L. Gutierrez, A. Weiss, Y. Leichtmann- Bardoogo, D. L. Zhang, D. R. Crooks, R. Sougrat, A. Morgenstern, B. Galy, M. W. Hentze, F. J. Lazaro, T. A. Rouault and E. G. Meyron-Holtz, Serum ferritin is derived primarily from macrophages through a nonclassical secretory pathway. Blood 2010 116:1574-1584; doi: https://doi.org/10.1182/blood-2009-11-253815
- Cappellini MD et al. Iron deficiency across chronic inflammatory conditions: international expert opinion on definition, diagnosis, and management. Am J Hematol. 2017; 92(10):1068–1078
- Martius et al. Eisenmangel ohne Anämie – ein heisses Eisen? Nicht hämatologische Auswirkungen des Eisenmangels: Welche sind belegt, wann kommen sie zum Tragen? Schweiz Med Forum 2009;9(15–16):294–299
- Verdon F et al. Iron supplementation for unexplained fatigue in non-anaemic women: double blind randomized placebo controlled trial. BMJ 2003, 326: 1124–1126
- Cornuz J et al. Fatigue: a practical approach to diagnosis in primary care. 2006, CMAJ, 174(6)
- Favrat B et al. Evaluation of a single dose of ferric carboxymaltose in fatigue, iron-deficient women–PREFER a randomized, placebo-controlled study. PLoS One 2014;9(4):e94217
- Houston BL et al. Efficacy of iron supplementation on fatigue and physical capacity in non-anaemic iron-deficient adults: a systematic review of randomized controlled trials. BMJ Open 2018 8(4):e019240
- Yokoi K et al. Iron deficiency without anaemia is a potential cause of fatigue: meta-analyses of randomized controlled trials and cross-sectional studies. Br J Nutr. 2017 117(10):1422–1431
- Murray-Kolb LE, Beard JL. Iron treatment normalizes cognitive functioning in young women. On J Clin Nutr 2007, 85: 778
- Low MS et al. Daily iron supplementation for improving anaemia, iron status and health in menstruating women. Cochrane Database Syst Rev. 2016 Apr 18;4:CD009747
- Geng F et al. Impact of fetal-neonatal iron deficiency on recognition memory at two months of age. J Pediatr. 2015; 167(6):1226–1232
- Berglund SK et al. Effects of iron supplementation of low-birth-weight infants on cognition and behavior at 7 years: a randomized controlled trial. Pediatr Res. 2018;83(1–1):111–118
- Allen RP et al. Evidence-based and consensus clinical practice guidelines for the iron treatment of restless legs syndrome/Willis-Ekbom disease in adults and children: an IRLSSG task force report. Sleep Med. 2018, 41, 27–44
- Ferric carboxymaltose in patients with restless legs syndrome and nonanemic iron deficiency: a randomized trial. Mov Disord. 2017;32(10):1478–1482
- Kantor J et al. Decreased serum ferritin is associated with alopecia in women. J Invest Dermatol 2003;121:985
- Deloche C et al. Low iron stores: a risk factor for excessive hair loss in non-menopausal women. Eur J Dermatol 2007;17:507–512
- Martines-Torres C et al. Effect of exposure to low temperature on normal and iron-deficient subjects. On J Physiol 1984, 246: R380–R383
- Scott L J. Ferric carboxymaltose: a review in iron deficiency. Drugs 2018;78(4):479–493
- Information for Healthcare professionals Ferinject®: www.swissmedicinfo.ch
- Geisser P. Safety and efficacy of iron(III)-hydroxyde polymaltose complex / a review of over 25 years experience. Arzneimittelforschung 2007;57(6A):439–52
- Geisser P. The pharmacology and safety profile of ferric carboxymaltose (Ferinject®): structure/reactivity relationships of iron preparations. Port J Nephrol Hypert 2009:23(1):11–16