As a result, the demand for iron also increases. While the body typically maximizes iron absorption during pregnancy, insufficient iron intake or other factors affecting the way iron is absorbed can lead to iron deficiency.
Low iron intake during pregnancy increases the risk of premature birth and low birth weight, as well as low iron stores and impaired cognitive or behavioral development in infants. Pregnant women with low iron may be more prone to infection because iron also supports the immune system. It is clear that iron supplements are needed for women who are both pregnant and iron-deficient.
However, research is ongoing as to the possibility of recommending additional iron to all pregnant women, even those with normal iron levels. It is argued that all pregnant women should take 30 to 60 milligrams mg of iron supplements on every day of their pregnancy, regardless of their iron levels.
Insufficient iron in the diet can affect the efficiency with which the body uses energy. Iron carries oxygen to the muscles and brain and is crucial for both mental and physical performance.
Low iron levels may result in a lack of focus, increased irritability, and reduced stamina. Iron deficiency is more common among athletes, especially young female athletes, than in individuals who do not lead an active lifestyle. This appears to be particularly true in female endurance athletes, such as long-distance runners.
Some experts suggest that female endurance athletes should add an additional 10 mg of elemental iron per day to the current RDA for iron intake. Iron deficiency in athletes decreases athletic performance and weakens immune system activity. Iron has a low bioavailability, meaning that the small intestine does not readily absorb large amounts. This decreases its availability for use and increases the likelihood of deficiency.
There are two types of dietary iron, known as heme and non-heme. Animal sources of food, including meat and seafood, contain heme iron. Heme iron is more easily absorbed by the body. Non-heme iron, the type found in plants, requires that the body take multiple steps to absorb it. Of the more than chemical elements known to scientists today, only a relatively small number of these elements are found in the human body.
In fact, only 24 different elements are thought to be essential for humans. The other elements in the body, such as calcium, phosphorus, iron, and copper, are known to physiologists as mineral elements and trace elements. Although these elements make up a much smaller percentage of the mass of the body, they are vital to the body's proper functioning. They must be present in the body in the proper amounts, and they must also be available to react with other elements to form critical molecules and participate in important chemical reactions.
In this tutorial, we will describe the importance of one essential mineral in the body, iron. Although iron comprises only 0. Because iron plays such a crucial role in the body, it is important for us to maintain an adequate supply of iron. Our bodies continually lose iron through everyday processes such as urination, defecation, sweating, and sloughing off skin cells. Bleeding contributes to further loss of iron from the body. To compensate for these losses and to maintain an adequate supply of iron, we should consume approximately 18 mg of iron daily.
Certain conditions, including heavy bleeding and pregnancy, further increase the requirement for iron consumption. Good dietary sources of iron include red meat, liver, egg yolk, beans, nuts, and fortified cereals. When the body's supply of available iron is too low, a condition known as iron deficiency results. People with iron deficiency cannot produce an adequate amount of hemoglobin to meet their body's oxygen-transport needs.
When the deficiency becomes severe such that there are too few circulating red blood cells or the hemoglobin content of these cells is very low, the condition is diagnosed as iron-deficiency anemia.
The most common symptoms of iron-deficiency anemia are tiredness and weakness due to the inadequate oxygen supply to the body's cells, and paleness in the hands and eyelids due to the decreased levels of oxygenated hemoglobin, which is red-colored. Iron-deficiency anemia can be treated with iron supplements. It is also possible to have too much iron deposited in the body tissues. This condition is known as iron overload.
If the iron overload becomes severe usually when the total amount of iron in the body exceeds 15 g , the condition is diagnosed as hemochromatosis. Hemochromatosis can result in serious damage to the body's tissues, including cirrhosis of the liver, heart failure, diabetes, abdominal pain, and arthritis. A recessive genetic mutation can put some people, particularly those of Irish or Celtic descent, at a higher risk for developing hemochromatosis.
Treatment for the condition consists of removing blood from the patient to decrease the amount of iron in the body. How does the body regulate the amount of iron? Fortunately, most of us are able to maintain appropriate levels of available iron in the body, even if our iron consumption does not always exactly match the body's iron loss. This regulation of blood-iron levels is mediated by the protein ferritin Figure 1. Ferritin can release iron if the blood has a low iron concentration, and it can help to store excess iron if the blood and tissues have a high iron concentration.
Hence, ferritin functions as a "buffer" against iron deficiency and, to a lesser extent, against iron overload. This is a three-dimensional representation of ferritin, the iron-storage protein in the body. Ferritin has a spherical shape, and iron brown is stored as a mineral inside the sphere. Note : This same molecule is shown in another type of representation in Figure 7 below.
How does ferritin store iron? Ferritin has the shape of a hollow sphere. Inside the sphere, iron is stored in the Fe III oxidation state. Then, the iron leaves through channels in the spherical structure. To understand how ferritin controls storage and release of iron, we need to first study its structure. We will use the different types of Molecular Representations to study the structure of ferritin. We will begin at the smallest level of protein structure by using 2D-ChemDraw representations to show how atoms are combined to make amino acids and how amino acids come together to form the protein subunits known as peptides.
We will then examine how the sequence of amino acids determines the shape of the peptide. Finally, we will use the ribbon and CPK representations to show how 24 peptide subunits are combined to make the hollow spherical shape and channels of ferritin.
The basic structural features of proteins that you will learn about in this tutorial will provide a foundation for understanding the structure and function of any protein, a tremendously important class of biological molecules. Hallberg L, Rossander L. Effect of different drinks on the absorption of non-heme iron from composite meals. Hum Nutr Appl Nutr. Inhibition of haem-iron absorption in man by calcium.
Hallberg L, Rossander-Hulthen L. Iron requirements in menstruating women. Lynch SR. The effect of calcium on iron absorption. Nutr Res Rev. Food iron absorption in human subjects. Comparison of the effect of animal proteins on nonheme iron absorption. Iron absorption in humans: Bovine serum albumin compared with beef muscle and egg white.
Inhibitory effect of a soybean-protein-related moiety on iron absorption in humans. Lead-induced abnormalities of porphyrin metabolism, the relationship with iron deficiency.
Goyer RA. Lead toxicity: Current concerns. Environ Health Perspect. Bangkok: Estimates of iron sufficiency in the US population. A general approach of the problems of iron deficiency and iron overload in the population at large. Semin Hematol. Serum ferritin and dietary iron parameters in a sample of Canadian preschool children.
J Can Dietetic Assoc. Geneva: World Health Organization; Preventing and controlling iron deficiency anaemia through primary health care: A guide for health administrators and programme managers; p. Dallman P. In: Brown ML, editor. Present Knowledge in Nutrition. Washington DC: Nutrition Foundation; Geneva: Switzerland: World Health Organization; Iron status and neural functioning. Failla ML. Trace elements and host defense: Recent advances and continuing challenges.
Viteri FE, Torun B. Anemia and physical work capacity. In: Garby L, editor. Clinics in Hematology. London: WB Saunders; World Health Organization, Geneva; Report of the WHO informal consultation on hookworm infection and anaemia in girls and women; p.
Nutritional impact of intestinal helminthiasis during the human life cycle. Relationship between intensity of soil-transmitted helminth infections and anemia during pregnancy. Am J Trop Med Hyg. Nutritional iron deficiency.
Impact of menstrual blood loss and diet on iron deficiency among women in the UK. Beard JL. Iron requirement in adolescent females.
Symposium: Improving adolescent iron status before childbearing. WHO; Expert consultation agrees on best indicators to assess iron deficiency, a major cause of anaemia.
Beguin Y. Soluble transferrin receptor for the evaluation of erythropoiesis and iron status. Clinica Chimica Acta. Baynes RD. Assessment of iron status.
Clin Biochem. The quantitative assessment of bodyiron. The influence of high altitude living on body iron. Comparison of plasma ferritinconcentration with the ratio of plasma transferrin receptor to ferritin inestimating body iron stores: Results of 4 intervention trials.
Library Cataloguing-in-Publication Data. Worldwide prevalence of anaemia WHO global database on anaemia; p. Diagnosis and management of iron deficiency anemia in the 21st century. Ther Adv Gastroenterol. Zarychanski R, Houston DS. Anemia of chronic disease: A harmful disorder or an adaptive, beneficial response? Can Med Assoc J. Weiss G, Goodnough LT. Anemia of chronic disease.
N Engl J Med. Geneva: Prevalence and outcomes of anemia in cancer: A systematic review of the literature. Am J Med. Anemia patients with chronic kidney diseases. Diabetes Spectrum. Nurko S. Anemia in chronic kidney disease: Causes, diagnosis, treatment. Cleve Clin J Med. Clin Lab Med. Is obesity associated with anemia of chronic disease? A population-based study.
Overweight children have higher circulating hepcidin concentrations and lower iron status but have dietary iron intakes and bioavailability comparable with normal weight children. Int J Obes.
Ballard HS. The hematological complications of alcoholism. Alcohol Health Res World. A case of persistent anemia and alcohol abuse. Nat Clin Pract Gastroenterol Hepatol. Lindenbaum J, Roman MJ. Nutritional anemia in alcoholism. Sickle cell anemia: Iron availability and nocturnal oximetry. J Clin Sleep Med. World Health Organization; Alpha and beta thalassemia. Am Fam Physician. Aplastic anemia: acquired and inherited. Williams Hematology. Current concepts in the pathophysiology and treatment of aplastic anemia.
Scheinberg P, Chen J. Aplastic Anemia: What have we learned from animal models and from the clinic. How to ensure adequate iron absorption from iron-fortified food. Nutr Rev. Cook JD. Diagnosis and management of iron-deficiency anaemia. Best Pract Res Clin Haematol. Phytate in foods and significance for humans: Food sources, intake, processing, bioavailability, protective role and analysis.
Mol Nutr Food Res. Effects of soaking, germination and fermentation on phytic acid, total and in vitro soluble zinc in brown rice.
For more information about building a healthy dietary pattern, see the Dietary Guidelines for Americans and the U. This fact sheet by the Office of Dietary Supplements ODS provides information that should not take the place of medical advice. We encourage you to talk to your healthcare providers doctor, registered dietitian, pharmacist, etc. Any mention in this publication of a specific product or service, or recommendation from an organization or professional society, does not represent an endorsement by ODS of that product, service, or expert advice.
Updated: March 22, History of changes to this fact sheet. Find ODS on:. Strengthening Knowledge and Understanding of Dietary Supplements. Health Information Health Information. Iron Fact Sheet for Consumers. Table of Contents What is iron and what does it do? How much iron do I need? What foods provide iron? What kinds of iron dietary supplements are available? Am I getting enough iron? What happens if I don't get enough iron?
What are some effects of iron on health? Can iron be harmful? Does iron interact with medications or other dietary supplements? Iron and healthful eating Where can I find out more about iron? Disclaimer This fact sheet by the Office of Dietary Supplements ODS provides information that should not take the place of medical advice.
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