How much iron is in the human body

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Iron Content in the Human Body: An Overview

Total Iron in the Human Body

The total iron content in an adult human body is approximately 3 to 5 grams. This iron is distributed across various components of the body, with the majority being found in hemoglobin within red blood cells, which accounts for about 60-70% of the total iron 259. The remaining iron is stored in the liver, spleen, and bone marrow in the form of ferritin and hemosiderin, which serve as iron reserves 569.

Iron Distribution and Storage

Hemoglobin and Myoglobin

Hemoglobin, the protein in red blood cells responsible for oxygen transport, contains the largest portion of the body's iron. In men, approximately 30 mg/kg of body weight is held in hemoglobin, while in women, this figure is slightly lower due to differences in body composition 27. Additionally, about 300 mg of iron is found in myoglobin, a protein that stores oxygen in muscles .

Ferritin and Hemosiderin

Ferritin and hemosiderin are the primary storage forms of iron in the body. These proteins are mainly located in the liver, spleen, and bone marrow, and they can store up to 1-2 grams of iron 569. This stored iron is crucial for regenerating hemoglobin, especially after blood loss due to physiological or pathological conditions .

Iron Absorption and Excretion

Absorption

Iron absorption occurs primarily in the small intestine and is tightly regulated by the body to prevent both deficiency and overload. The protein hepcidin, produced by the liver, plays a key role in controlling iron absorption by regulating the activity of ferroportin, the only known iron exporter in human cells . On average, about 1-2 mg of iron is absorbed from the diet daily .

Excretion

The human body has a very limited capacity to excrete iron. Daily iron losses are minimal, averaging around 1 mg per day, and occur mainly through the shedding of mucosal and skin cells, as well as in bile 145. Menstruating women have higher iron losses, which can range from 0.65 to 4.88 mg per day, primarily due to menstrual blood loss .

Conclusion

In summary, the human body contains approximately 3 to 5 grams of iron, with the majority found in hemoglobin and the rest stored in ferritin and hemosiderin. Iron absorption is tightly regulated to maintain balance, and excretion is minimal, highlighting the importance of dietary iron intake to meet the body's needs. Understanding these dynamics is crucial for addressing conditions related to iron deficiency and overload.

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Most relevant research papers on this topic

Body iron excretion in man: a collaborative study.

Daily iron losses in adult males vary, with higher losses in Bantu populations due to greater than normal iron stores, and excessive sweating does not significantly impact iron excretion.

Observational StudyHighly Cited

1968·

363citations

·R. Green et al.

Iron kinetics with emphasis on iron overload.

Iron kinetics plays a crucial role in understanding anemia and iron overload states, with three main aspects to consider: external iron exchange, internal iron exchange, and storage iron exchange.

1973·

59citations

·J. Cook et al.

The quantitative assessment of body iron.

This study presents a reliable method for estimating body iron based on the ratio of serum transferrin receptor to serum ferritin, which enhances iron status evaluation and sensitivity in iron intervention trials.

Observational StudyHighly Cited

2003·

798citations

·J. Cook et al.

Body iron excretion by healthy men and women.

Direct iron excretion measurements in healthy men and women confirm the wide range of iron requirements in humans, with menstrual iron accounting for 90% of the variation.

Observational StudyVery Rigorous JournalHighly Cited

2009·

98citations

·J. Hunt et al.

IRON METABOLISM

There is no regulated excretion of iron by the colon, and iron absorption is controlled by a protein called apoferritin in the small intestine.

1950·

1citation

·Colin Ratledge

Estimation of Body Iron Stores

Hemoglobin accounts for up to 80% of total body iron in young women and 60% in men, while storage iron in the liver, spleen, and bone marrow helps regenerate hemoglobin after blood loss.

2012·

8citations

·M. Worwood

Iron Homeostasis and the Assessment of Iron Status

Iron homeostasis is crucial for maintaining health, but excessive iron can be toxic, with deficiency affecting 500 million people and overload causing severe consequences.

1998·

48citations

·R. Sherwood et al.

Intravenous iron therapy in heart failure: a different perspective

Intravenous iron therapy is a common treatment for heart failure, but its effectiveness in preventing iron deficiency is controversial.

2019·

13citations

·K. Ghafourian et al.

Iron and Chronic Liver Disease

Chronic liver disease can lead to iron overload, causing a build-up of iron in the liver and spleen, leading to iron deficiency and a need for iron supplements.

1973·

18citations

·M. Barry

Assessment of Iron in Human Tissue: The Magnetic Biopsy

Magnetic biopsy is a reliable and non-invasive method for assessing iron levels in human tissue, providing valuable diagnostic clues for various disorders and malignancies.

1983·

7citations

·D. Farrell

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