In a study of 2, blood donors, men who had given at least three and women who had given at least two whole-blood donations in the previous year were more than five times as likely to have depleted iron stores as first-time donors [ 53 ].
A clinical trial of iron supplementation found that of adults who had donated a unit of blood within the past 3—8 days, those randomized to take an iron supplement Without iron supplementation, two-thirds of the donors had not recovered the iron they lost, even after 24 weeks. The main causes of iron deficiency in people with cancer are anemia of chronic disease discussed in the Iron and Health section below and chemotherapy-induced anemia.
However, chronic blood loss and deficiencies of other nutrients due, for example, to cancer-induced anorexia can exacerbate iron deficiency in this population. The combination of low iron intake and high iron loss can lead to a negative iron balance; reduced production of hemoglobin; or microcytic, hypochromic anemia [ 58 ].
Potential causes of iron deficiency in people with heart failure include poor nutrition, malabsorption, defective mobilization of iron stores, cardiac cachexia, and use of aspirin and oral anticoagulants, which might result in the loss of some blood in the gastrointestinal tract [ 61 ]. This section focuses on the role of iron in IDA in pregnant women, infants, and toddlers, as well as in anemia of chronic disease.
Rates of deficiency were 6. Randomized controlled trials have shown that iron supplementation can prevent IDA in pregnant women and related adverse consequences in their infants [ 66 , 67 ]. In the same review, use of daily iron supplements was associated with an 8.
In addition, mean birthweight was 31 g higher for infants whose mothers took daily iron supplements during pregnancy compared with the infants of mothers who did not take iron. Guidelines on iron supplementation during pregnancy vary, but many recommend some form of iron supplementation to prevent IDA:. The IOM notes that because the median intake of dietary iron by pregnant women is well below the EAR, pregnant women need iron supplementation [ 5 ].
The Dietary Guidelines for Americans advises that women who are pregnant take an iron supplement when recommended by an obstetrician or other health-care provider [ 19 ]. It adds that low intakes of iron are a public health concern for pregnant women. The prevalence of IDA in U. Full-term infants typically have adequate iron stores for approximately the first 4 to 6 months, but the risk of iron deficiency in low-birthweight and preterm infants begins at birth because of their low iron stores.
IDA in infancy can lead to adverse cognitive and psychological effects, including delayed attention and social withdrawal; some of these effects might be irreversible [ 2 , 20 ]. In addition, IDA is associated with higher lead concentrations in the blood although the cause of this is not fully understood , which can increase the risk of neurotoxicity [ 20 ]. Another Cochrane review of 8 trials in 3, children younger than 2 in low-income countries showed that home fortification of semi-solid foods with micronutrient powders containing Guidelines vary on dietary iron intakes and possible supplementation to ensure adequate iron status and to prevent or treat IDA in infants and young children:.
Some studies have suggested that iron supplementation in young children living in areas where malaria is endemic could increase their risk of malaria [ 75 , 76 ]. However, a Cochrane review of 33 trials in 13, children showed that intermittent supplementation does not appear to have this effect [ 77 ]. The WHO therefore recommends 6-month supplementation cycles as follows: children aged 24 to 59 months should receive 25 mg iron and those aged 5 to 12 years should receive 45 mg every week for 3 months, followed by 3 months of no supplementation [ 75 ].
The WHO recommends providing these supplements in malaria-endemic areas in conjunction with measures to prevent, diagnose, and treat malaria. Certain inflammatory, infectious, and neoplastic diseases such as rheumatoid arthritis, inflammatory bowel disease, and hematologic malignancies can cause anemia of chronic disease, also known as anemia of inflammation [ 2 , 78 ]. Anemia of chronic disease is the second most common type of anemia after IDA [ 79 ].
In people with anemia of chronic disease, inflammatory cytokines upregulate the hormone hepcidin. As a result, iron homeostasis is disrupted and iron is diverted from the circulation to storage sites, limiting the amount of iron available for erythropoiesis.
Anemia of chronic disease is usually mild to moderate hemoglobin levels 8 to 9. The condition can be difficult to diagnose because, although low serum ferritin levels indicate iron deficiency, these levels tend to be higher in patients with infection or inflammation [ 80 ]. The clinical implications of iron deficiency in people with chronic diseases are not clear. Even mild anemia of chronic disease is associated with an increased risk of hospitalization and mortality in elderly people [ 81 ].
Two prospective observational studies found that iron deficiency in patients with objectively measured heart failure was associated with an increased risk of heart transplantation and death, and this association was independent of other well-established prognostic factors for poor outcomes, including anemia [ 82 , 83 ]. However, an analysis of NHANES data on adults with self-reported heart failure found no association between iron deficiency and all-cause or cardiovascular mortality [ 60 ].
The main therapy for anemia of chronic disease is treatment of the underlying disease [ 79 ]. The use of iron supplements—whether oral, intravenous, or parenteral—in this setting is controversial because they might increase the risk of infection and cardiovascular events and could cause tissue damage [ 79 ]. Only a few small studies have evaluated the benefits of oral iron supplementation alone or in combination with ESAs to treat anemia of chronic disease.
Iron administered parentally increases hemoglobin levels to a greater extent and is associated with fewer side effects than oral iron supplementation in patients with anemia of chronic disease [ 86 ]. Adults with normal intestinal function have very little risk of iron overload from dietary sources of iron [ 2 ]. Taking supplements containing 25 mg elemental iron or more can also reduce zinc absorption and plasma zinc concentrations [ 3 , 87 , 88 ]. In severe cases e. Between and , at least 43 U.
Accidental ingestion of iron supplements caused about a third of poisoning deaths among children reported in the United States between and In , the FDA began requiring oral supplements containing more than 30 mg elemental iron per dose to be sold in single-dose packaging with strong warning labels. At the same time, many manufacturers voluntarily replaced the sugar coating on iron tablets with film coatings.
Between and , only one child death due to ingesting an iron-containing tablet was reported [ 27 ]. As a result of a court decision, the FDA removed its single-dose packaging requirement for iron supplements in [ 90 ]. FDA currently requires that iron-containing dietary supplements sold in solid form e. Keep this product out of reach of children. In case of accidental overdose, call a doctor or poison control center immediately" [ 91 ].
In addition, since , the Consumer Product Safety Commission has required manufacturers to package dietary supplements containing mg or more elemental iron per container in child-resistant bottles or packaging to prevent accidental poisoning [ 92 , 93 ]. Hemochromatosis, a disease caused by a mutation in the hemochromatosis HFE gene, is associated with an excessive buildup of iron in the body [ 3 , 39 , 94 ].
The condition is much less common in other ethnic groups. Without treatment by periodic chelation or phlebotomy, people with hereditary hemochromatosis typically develop signs of iron toxicity by their 30s [ 3 ]. These effects can include liver cirrhosis, hepatocellular carcinoma, heart disease, and impaired pancreatic function.
The American Association for the Study of Liver Diseases recommends that treatment of hemochromatosis include the avoidance of iron and vitamin C supplements [ 39 ]. The FNB has established ULs for iron from food and supplements based on the amounts of iron that are associated with gastrointestinal effects following supplemental intakes of iron salts see Table 3.
The ULs apply to healthy infants, children, and adults. Physicians sometimes prescribe intakes higher than the UL, such as when people with IDA need higher doses to replenish their iron stores [ 5 ]. Iron can interact with certain medications, and some medications can have an adverse effect on iron levels. A few examples are provided below.
Individuals taking these and other medications on a regular basis should discuss their iron status with their healthcare providers. In the United States, the labels for levodopa warn that iron-containing dietary supplements might reduce the amount of levodopa available to the body and, thus, diminish its clinical effectiveness [ 99 , ].
The simultaneous ingestion of iron and levothyroxine can result in clinically significant reductions in levothyroxine efficacy in some patients [ ]. The labels for some of these products [ , ] warn that iron supplements can reduce the absorption of levothyroxine tablets and advise against administering levothyroxine within 4 hours of iron supplements.
Gastric acid plays an important role in the absorption of nonheme iron from the diet. Treatment with proton pump inhibitors for up to 10 years is not associated with iron depletion or anemia in people with normal iron stores [ ]. But patients with iron deficiency taking proton pump inhibitors can have suboptimal responses to iron supplementation [ ]. The federal government's — Dietary Guidelines for Americans notes that "Because foods provide an array of nutrients and other components that have benefits for health, nutritional needs should be met primarily through foods.
In some cases, fortified foods and dietary supplements are useful when it is not possible otherwise to meet needs for one or more nutrients e. For more information about building a healthy dietary pattern, refer to the Dietary Guidelines for Americans and the U.
Department of Agriculture's MyPlate. 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 30, 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 Health Professionals. Iron Other Resources. References Wessling-Resnick M. Modern Nutrition in Health and Disease. Aggett PJ. Present Knowledge in Nutrition. Washington, DC: Wiley-Blackwell; Encyclopedia of Dietary Supplements. London and New York: Informa Healthcare; Hurrell R, Egli I.
Iron bioavailability and dietary reference values. Food and Nutrition Board. Drakesmith H, Prentice AM. Hepcidin and the Iron-Infection Axis.
Science ; Introduction to workshop on iron screening and supplementation in iron-replete pregnant women and young children. Am J Clin Nutr. Disorders of iron metabolism: New diagnostic and treatment approaches to iron deficiency. Hematol Oncol Clin North Am. J Nutr. Geneva; DeLoughery TG.
Microcytic anemia. N Engl J Med. Iron deficiency anemia. Med Clin North Am. Iron deficiency anemia: evaluation and management. Am Fam Physician. Assessment of Iron Status.
In: Principles of Nutritional Assessment. Side effects occurred more frequently after the intake of ferrous sulphate than ferrous gluconate. Conclusion: High doses of oral iron were well absorbed and tolerated in PD patients. Ferrous gluconate was better absorbed and tolerated than ferrous sulphate, thus we recommend it for oral iron supplementation in PD patients. Publication types English Abstract. Elemental iron is the more important number because this is the amount available for the body to absorb.
However, a physician may not specify in a prescription if the iron amount is the chemical form or the elemental iron. For example, a ferrous sulfate iron supplement may list a total of mg of ferrous sulfate on the front of the label but 65 mg of elemental iron in smaller print on the back.
If a physician prescribed 65 mg of iron, would you take five pills to equal mg, or just one pill, assuming the prescription referred to elemental iron?
Different types. All types of supplemental iron help to increase red blood cell production but vary in cost and amounts of elemental iron. Ferrous gluconate is usually sold in liquid form and some clinical studies have shown that it is better absorbed than ferrous sulfate tablets.
However, ferrous gluconate contains less elemental iron than ferrous sulfate, so a greater dosage may be needed to correct a deficiency. It is also more expensive than ferrous sulfate. Newer slow-release forms of iron have been introduced, which may help reduce gastrointestinal side effects, but they are more expensive and usually contain less iron. Any confusion with iron supplement types and amounts can be resolved by asking your doctor to specify both the elemental amount and the chemical compound amount.
An iron deficiency is seen most commonly in children, women who are menstruating or pregnant, and those eating a diet lacking in iron. Iron deficiency occurs in stages. If this does not resolve, the next stage is a greater depletion of iron stores and a drop in red blood cells. Eventually this leads to iron-deficiency anemia IDA where iron stores are used up and there is significant loss of total red blood cells. Typically, a doctor screens for anemia by first checking a complete blood count including hemoglobin, hematocrit, and other factors that measure red blood cell volume and size.
If this is below normal, ferritin and transferrin levels may be measured to determine if the type of anemia is IDA there are other forms of anemia not caused specifically by an iron deficiency. All of these measures would decrease with IDA. IDA is usually corrected with oral iron supplements of up to mg of elemental iron daily. Those at high risk of IDA may be prescribed mg daily. Blood levels should be rechecked periodically, and supplements discontinued or taken at a lower dosage if levels return to normal, as long-term high dosages can lead to constipation or other digestive upset.
Anemia of chronic disease AOCD occurs not from a low iron intake but with conditions that cause inflammation in the body, such as infections, cancer, kidney disease, inflammatory bowel disease, heart failure, lupus, and rheumatoid arthritis.
The body may actually contain normal amounts of iron, but levels in the blood are very low. Treatment for AOCD focuses on treating the inflammatory condition. Increasing iron in the diet typically does not help. If the inflammation or condition improves, the anemia will usually decrease as well. In rare severe cases, a blood transfusion can be given to quickly boost the amount of hemoglobin in the blood.
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