Why Would a Body Stop Absorbing Iron?

December 24, 2025 •

4 min read

Worldwide, iron deficiency is the most common nutritional deficiency, and a body can stop absorbing iron for numerous medical and lifestyle reasons. This can lead to a condition known as iron-deficiency anemia, causing fatigue and other serious health problems.

Quick Summary

Several factors can cause the body to stop absorbing iron effectively, including gastrointestinal disorders, specific medical conditions, and lifestyle factors. The liver hormone hepcidin plays a central regulatory role, inhibiting iron absorption during inflammation. Diagnosis involves blood tests to identify the underlying cause, which may require specific treatment beyond simple iron supplementation.

Key Points

Hepcidin Hormone: Elevated levels of hepcidin, often triggered by inflammation, are a major reason for iron malabsorption, as this hormone blocks the release of iron into the bloodstream.
Gastrointestinal Damage: Disorders like celiac disease and inflammatory bowel disease damage the small intestine's lining, directly preventing efficient iron absorption.
Bariatric Surgery Effects: Post-gastric bypass procedures, the surgical rerouting of the digestive system bypasses the duodenum, leading to long-term iron malabsorption.
Medication and Diet: Medications like proton pump inhibitors and certain dietary inhibitors (e.g., phytates, tannins, calcium) can significantly reduce iron uptake.
Chronic Illness: Anemia of chronic disease, linked to inflammatory conditions and illnesses such as chronic kidney disease, can trigger high hepcidin and disrupt iron metabolism.

The body's intricate system for regulating iron absorption can be disrupted by various internal and external factors, leading to a state of iron deficiency. The primary site for iron absorption is the duodenum, the first section of the small intestine. When this process is compromised, a person can develop iron deficiency even with an iron-rich diet. Understanding the mechanisms involved is crucial for proper diagnosis and treatment.

The Role of Hepcidin: The Master Regulator

One of the most significant reasons the body stops absorbing iron is an elevated level of the hormone hepcidin. Produced primarily by the liver, hepcidin acts as a master regulator of iron homeostasis. Its main function is to control the amount of iron released into the bloodstream from intestinal cells and iron-recycling macrophages.

During inflammation: In response to inflammation or infection, cytokine proteins like interleukin-6 signal the liver to increase hepcidin production. Elevated hepcidin levels degrade ferroportin, the protein responsible for exporting iron from cells, effectively trapping iron within storage cells. This protective mechanism, known as anemia of chronic disease, withholds iron from potential pathogens, but it also reduces iron availability for red blood cell production.
With iron overload: When the body's iron stores are high, hepcidin production naturally increases to prevent further absorption. However, genetic disorders like hereditary hemochromatosis can cause inappropriately low hepcidin, leading to iron overload. Conversely, in iron-refractory iron deficiency anemia (IRIDA), mutations can cause hepcidin levels to be inappropriately high, hindering iron absorption despite deficiency.

Gastrointestinal Disorders and Malabsorption

Damage to the intestinal lining is a direct cause of poor iron absorption, as the small intestine is where most iron is absorbed.

Celiac Disease: This autoimmune disorder triggers an inflammatory response in the small intestine when gluten is consumed, damaging the villi responsible for nutrient absorption. This damage is a leading cause of iron malabsorption, which can persist even after starting a gluten-free diet if the gut lining hasn't fully healed.
Inflammatory Bowel Disease (IBD): Chronic inflammation from conditions like Crohn's disease and ulcerative colitis can inhibit iron absorption through mucosal damage and the hepcidin pathway. Furthermore, inflammation-related occult gastrointestinal bleeding can exacerbate iron deficiency.
Helicobacter pylori Infection: This bacterial infection can cause atrophic gastritis, leading to decreased stomach acid (hypochlorhydria). Acid is necessary to convert non-heme iron into a more absorbable form, so its reduction impairs iron uptake. H. pylori can also cause chronic inflammation and minor bleeding.
Gastric Bypass Surgery: Procedures like Roux-en-Y gastric bypass reroute food past the duodenum, the primary site of iron absorption. This bypass is a very common cause of lifelong iron malabsorption, requiring permanent monitoring and supplementation.

Impact of Medications and Dietary Factors

Certain medications and compounds found in food can interfere with the iron absorption process, even in a healthy digestive system.

Medications: Proton pump inhibitors (PPIs) and other antacids reduce stomach acid, which hinders iron conversion and absorption. Calcium supplements can also interfere with iron absorption when taken at the same time.
Dietary Inhibitors: Several compounds inhibit non-heme iron absorption, such as phytates (in whole grains and legumes), polyphenols and tannins (in tea, coffee, and some fruits and vegetables), and oxalates (in spinach, rhubarb, and nuts). The presence of calcium in dairy products also inhibits both heme and non-heme iron absorption.

Other Conditions Affecting Iron Absorption

Less common but equally important conditions can also interfere with iron absorption.

Chronic Kidney Disease: Individuals with CKD often experience inflammation that elevates hepcidin levels, leading to anemia of chronic disease.
Rare Genetic Disorders: Inherited conditions, such as Iron-Refractory Iron Deficiency Anemia (IRIDA) caused by a TMPRSS6 gene mutation, result in excessive hepcidin production, making it difficult to absorb iron.

Comparison of Major Causes of Iron Malabsorption


Cause	Primary Mechanism	Location of Impact	Management Strategy	Iron Supplement Response
Celiac Disease	Villous atrophy due to gluten exposure; chronic inflammation.	Duodenum and small intestine.	Strict gluten-free diet to allow mucosal healing.	Initial response may be poor; improves with mucosal healing.
Chronic Inflammation	High hepcidin levels block iron transport via ferroportin.	Systemic; affects gut and iron-recycling macrophages.	Manage underlying inflammatory condition.	Often poor, may require intravenous iron.
Gastric Bypass Surgery	Anatomical bypass of the duodenum, reduced stomach acid.	Stomach and upper small intestine.	Lifelong supplementation and monitoring.	Oral supplements are often ineffective; intravenous iron may be needed.
H. pylori Infection	Hypochlorhydria (low stomach acid), inflammation.	Stomach.	Eradicate bacterial infection with antibiotics.	Absorption improves after successful eradication.

Conclusion

When a body stops absorbing iron effectively, the causes are often systemic and complex, extending far beyond simple dietary intake. The interplay of regulatory hormones like hepcidin, the integrity of the gastrointestinal tract, and other chronic health conditions all contribute to the body's ability to process and utilize this vital mineral. For conditions like celiac disease or gastric bypass, the path to iron deficiency is tied to physical changes in the digestive system. In other cases, such as anemia of chronic disease or H. pylori infection, the root cause is inflammatory, and managing the underlying disease is key to restoring normal iron balance. It is important to remember that diagnosing the specific cause is essential, as simple oral supplementation may be ineffective or inappropriate depending on the reason for malabsorption. Consulting a healthcare provider for accurate diagnosis and a tailored treatment plan is the most effective approach to correcting iron deficiency.

Frequently Asked Questions

The primary cause is often multi-faceted, but common reasons include chronic inflammation (which elevates hepcidin) and damage to the small intestine from conditions like celiac disease, which is the main site of iron absorption.

While iron deficiency is common in undiagnosed celiac disease due to intestinal damage, it may not be present in all cases. Some patients may experience continued malabsorption even after starting a gluten-free diet if the intestinal lining doesn't fully heal.

Stomach acid is crucial for converting non-heme iron into a form the body can absorb. Reduced stomach acid, caused by antacid medications or certain infections like H. pylori, can therefore lead to iron malabsorption.

Yes, tea and coffee contain polyphenols and tannins that bind to non-heme iron, significantly inhibiting its absorption. Consuming these beverages with meals can lower the amount of iron the body absorbs from plant-based foods.

During chronic inflammation, the body produces high levels of hepcidin. This hormone blocks iron transport, trapping it in storage and preventing it from being used for red blood cell production, leading to anemia of chronic disease.

Oral iron supplementation may be ineffective or poorly absorbed if the underlying cause is a systemic issue, such as inflammation or duodenal damage from celiac disease. In some cases, intravenous iron therapy may be required.

Symptoms can include fatigue, weakness, pale skin, headaches, rapid heartbeat, hair loss, brittle nails, and shortness of breath. These symptoms are often the result of iron-deficiency anemia.