A Nutrition Diet Guide: Where is the most iron found in the body?

October 31, 2025 •

5 min read

With approximately 70% of the body's iron residing in the hemoglobin of red blood cells, understanding precisely where is the most iron found in the body is fundamental to comprehending its vital role in oxygen transport and overall health. Iron's distribution throughout the body is intricately managed to ensure this essential mineral is available for critical functions while being safely stored when in excess.

Quick Summary

The majority of iron in the human body is concentrated within red blood cells for oxygen transport. Other major storage sites include the liver, spleen, and bone marrow. Proper iron intake through a balanced diet is crucial for maintaining optimal levels and supporting vital bodily functions.

Key Points

Red Blood Cells are the Primary Iron Repository: Around 70% of the body's iron is bound to hemoglobin within red blood cells, enabling critical oxygen transport.
The Liver is the Major Storage Organ: The liver, along with the spleen and bone marrow, stores excess iron in proteins called ferritin and hemosiderin, acting as the body's iron reserve.
Iron's Function Extends Beyond Blood: Iron is also a component of myoglobin in muscle tissue, where it helps store and release oxygen for muscle activity.
Absorption is Regulated by Hepcidin: A hormone called hepcidin, produced by the liver, controls the entry of dietary iron into the bloodstream to prevent toxic iron overload.
Dietary Iron Comes in Two Forms: Heme iron from animal products is more readily absorbed than non-heme iron from plant sources, though both are important for a balanced diet.
Iron Levels Affect Health: Imbalances can lead to serious conditions like iron-deficiency anemia from too little iron or hemochromatosis from excessive accumulation.

The Primary Location of Iron: Red Blood Cells

The majority of the body's iron, about 70%, is directly involved in oxygen transport and is concentrated within the hemoglobin of red blood cells. Hemoglobin is the protein molecule that carries oxygen from the lungs to the body's tissues. Without a sufficient amount of iron, the body cannot produce enough hemoglobin, which leads to a condition known as iron-deficiency anemia. Each day, the body recycles a significant portion of its iron from old red blood cells that are broken down, highlighting the efficiency of this closed metabolic system.

The Critical Role of Hemoglobin

Iron is the central atom in the heme group of hemoglobin, which reversibly binds to oxygen. The binding of oxygen to iron in the lungs allows red blood cells to deliver oxygen to all parts of the body. When red blood cells have completed their life cycle of about 120 days, they are removed from circulation by macrophages in the spleen and liver. The iron is then recycled and transported to the bone marrow to produce new red blood cells.

Iron Storage in the Body

Beyond its role in oxygen transport, the body maintains a strategic reserve of iron for future needs. The primary storage sites for iron are the liver, spleen, and bone marrow. This stored iron is held within two key proteins: ferritin and hemosiderin.

Ferritin: This is the body's main iron storage protein and is found in most cells. When the body has sufficient iron, excess iron is converted into ferritin for storage. A blood test for serum ferritin can provide a useful estimate of the body's overall iron stores.
Hemosiderin: When iron stores exceed the capacity of ferritin, the iron is stored in a less soluble and more slowly mobilized form called hemosiderin. While ferritin is the primary, more accessible form of stored iron, hemosiderin acts as a longer-term reserve, particularly in conditions of iron overload.

The Function of Myoglobin

Another important location for iron is in muscle cells, where it is a component of the protein myoglobin. Myoglobin functions similarly to hemoglobin but is found in muscle tissue, where it accepts, stores, and releases oxygen to support muscle activity. This provides a local oxygen reserve for muscles, especially during high-intensity exercise.

Regulation of Iron Homeostasis

Since the body has no active mechanism for excreting excess iron, the regulation of iron absorption is crucial. This is primarily controlled by a liver-derived hormone called hepcidin.

High Iron Levels: When iron levels are high, the liver increases hepcidin production. Hepcidin then binds to and degrades the protein ferroportin, which is responsible for transporting iron from cells into the bloodstream. This reduces iron absorption from the intestine and traps iron in storage cells.
Low Iron Levels: When the body is iron-deficient, hepcidin production is suppressed. This allows ferroportin to remain on cell surfaces, increasing iron absorption and facilitating its release from storage sites.

Dietary Iron: Heme vs. Non-Heme

The iron you consume from food comes in two forms, which have different sources and rates of absorption.


Feature	Heme Iron	Non-Heme Iron
Source	Animal-based foods like red meat, poultry, and seafood.	Plant-based foods like spinach, lentils, fortified cereals, and nuts.
Absorption Rate	Higher and more efficient (15–35%). Not significantly affected by other dietary factors.	Lower and less efficient (2–20%). Highly influenced by other food components.
Absorption Enhancers	Absorption is not notably enhanced by other foods.	Vitamin C significantly enhances absorption. Combining with heme iron also increases absorption.
Absorption Inhibitors	Negatively affected by calcium.	Inhibited by phytates (in grains, legumes), polyphenols (in tea, coffee), and calcium.

Building an Iron-Rich Diet

To maintain adequate iron levels, it is important to include a variety of iron-rich foods in your diet. Combining these foods with vitamin C can dramatically increase absorption, especially for non-heme sources.

Best Iron Sources:

Animal Sources (Heme): Red meat (beef, liver), poultry (especially dark meat), and seafood (oysters, clams, salmon) are excellent sources.
Plant Sources (Non-Heme):
- Legumes: Lentils, chickpeas, beans, and peas.
- Nuts and Seeds: Pumpkin seeds, cashews, and nuts.
- Vegetables: Spinach, kale, broccoli, and other dark leafy greens.
- Fortified Grains: Iron-fortified breakfast cereals, bread, and pasta.
- Dried Fruits: Raisins and dried apricots.

Practical Dietary Tips

Pair with Vitamin C: Squeeze lemon juice over spinach or add bell peppers to a bean dish to boost non-heme iron absorption.
Cook in Cast Iron: Cooking acidic foods in a cast-iron pan can increase the food's iron content.
Avoid Inhibitors: Limit your intake of tea and coffee with meals, as they contain polyphenols that can hinder iron absorption.

What Happens When Iron Levels Are Imbalanced?

Imbalances in iron levels can lead to significant health problems. The most common is iron-deficiency anemia, but iron overload can also be very dangerous.

Iron Deficiency Anemia

When iron levels are low, the body cannot produce enough healthy red blood cells, leading to anemia. Symptoms can develop gradually and include:

Extreme fatigue and weakness
Pale skin
Shortness of breath or chest pain
Headaches and dizziness
Brittle nails and hair loss
Restless legs syndrome
Craving for non-food items like ice or clay (pica)

Iron Overload (Hemochromatosis)

Excessive iron accumulation, often due to a genetic disorder called hemochromatosis, can be toxic to the body. Without a way to excrete large amounts of iron, it is deposited in various organs, including the liver, heart, and pancreas, causing tissue damage over time. This can lead to serious complications such as cirrhosis, heart failure, and diabetes.

Conclusion

The vast majority of iron in the human body is contained within the hemoglobin of red blood cells, which is crucial for delivering oxygen to every cell. Significant stores of iron are also maintained in the liver, spleen, and bone marrow within ferritin and hemosiderin proteins, acting as vital reserves. A delicate hormonal system, centered on hepcidin, tightly regulates iron absorption to ensure this mineral is both sufficiently supplied and safely stored, protecting against both deficiency and toxic overload. By understanding where iron is distributed and how to support its function through a balanced diet rich in both heme and non-heme sources, individuals can proactively manage their health and prevent related complications. Consult a healthcare provider or a registered dietitian if you have concerns about your iron levels or dietary intake.

Visit the Office of Dietary Supplements for more information.

Frequently Asked Questions

The main protein responsible for storing iron within the body is ferritin. Most cells contain ferritin, and the liver, spleen, and bone marrow are particularly rich in this protein for iron storage.

The body must absorb iron from the foods and drinks we consume. It absorbs iron primarily in the small intestine, and a portion of this iron is then used for immediate needs, with the rest being stored.

Heme iron comes from animal sources and is more easily and efficiently absorbed by the body. Non-heme iron comes from plant sources and is less efficiently absorbed, with its absorption being influenced by other dietary factors.

Good sources of heme iron include red meat, poultry, and seafood. Excellent non-heme iron sources include legumes (lentils, beans), leafy greens (spinach, kale), nuts, seeds, and fortified cereals.

You can significantly increase the absorption of non-heme iron by consuming it with a source of vitamin C, such as citrus fruits, bell peppers, or tomatoes. Cooking in a cast-iron skillet can also help.

Common symptoms include extreme fatigue, unexplained weakness, pale skin, shortness of breath, headaches, brittle nails, and restless legs syndrome. In severe cases, it can lead to iron-deficiency anemia.

Excess iron can be toxic and lead to organ damage in conditions like hemochromatosis. The body deposits this excess iron in organs like the liver and heart, which can impair their function over time.