What can cause iron deficiency?: Understanding the Root Causes

October 13, 2025 •

4 min read

According to the World Health Organization, iron deficiency is the most common nutritional disorder worldwide, affecting billions. Understanding what can cause iron deficiency is the first step toward effective prevention and management for better overall health.

Quick Summary

Iron deficiency is primarily caused by chronic blood loss, poor dietary intake, or impaired nutrient absorption. Increased physiological demands and underlying chronic diseases can also lead to depleted iron stores.

Key Points

Chronic Blood Loss is a Major Cause: In many cases, iron deficiency is caused by slow, continuous blood loss, often from heavy menstrual periods or gastrointestinal bleeding.
Absorption Issues Play a Critical Role: Medical conditions like celiac disease, inflammatory bowel disease, or certain surgeries can prevent the body from properly absorbing dietary iron.
Increased Needs during Growth and Pregnancy: The body requires significantly more iron during periods of rapid growth in children and during pregnancy, which can deplete stores if not managed.
Dietary Factors Influence Absorption: The bioavailability of iron differs between animal (heme) and plant (non-heme) sources. Consuming enhancers like Vitamin C and limiting inhibitors like tea and coffee is important for maximizing intake.
Chronic Inflammation Affects Iron Metabolism: Long-term diseases such as kidney failure, cancer, and autoimmune disorders can trigger inflammation that inhibits the body's ability to regulate and use iron.
Identifying the Root Cause is Key for Treatment: Addressing the underlying reason for the deficiency, rather than just taking supplements, is essential for a permanent solution and proper management.

The Importance of Iron

Iron is an essential mineral vital for many bodily functions. Most notably, it is a key component of hemoglobin, the protein in red blood cells that transports oxygen from the lungs to the body's tissues. When iron levels are insufficient, hemoglobin production is reduced, leading to anemia. Iron is also critical for physical growth, neurological development, cellular function, and hormone synthesis.

Primary Causes of Iron Deficiency

Iron deficiency is not always caused by diet alone. It often results from a combination of factors that disrupt the delicate balance between iron intake, absorption, and loss. The most common causes include chronic blood loss, inadequate dietary intake, impaired absorption, and increased physiological needs.

Chronic Blood Loss

In many adults, especially women of childbearing age, blood loss is the primary reason for iron deficiency. Since red blood cells contain iron, losing blood means losing iron.

Heavy Menstruation (Menorrhagia): Women with heavy or prolonged menstrual periods are at a significantly higher risk of developing iron deficiency due to the consistent monthly loss of blood.
Gastrointestinal (GI) Bleeding: Slow, chronic blood loss from the GI tract is a major cause in both men and postmenopausal women. This can be due to conditions such as:
- Peptic ulcers
- Colon polyps
- Inflammatory bowel diseases (IBD), like Crohn's disease or ulcerative colitis
- Gastrointestinal cancers
- Regular use of nonsteroidal anti-inflammatory drugs (NSAIDs), such as aspirin or ibuprofen, which can irritate the stomach lining
Frequent Blood Donation: Regular blood donors lose iron with every donation and may need to increase their intake or take supplements to prevent deficiency.
Childbirth: Blood loss during delivery and the iron needs of the fetus can deplete a mother's iron stores.

Inadequate Dietary Intake

While less common as the sole cause in countries with access to fortified foods, a diet low in bioavailable iron can contribute to deficiency, particularly in certain populations.

Vegetarian and Vegan Diets: Plant-based diets require careful planning. Heme iron, found in meat, poultry, and fish, is more easily absorbed by the body than non-heme iron from plants. Vegetarians must consume more iron and pair it with absorption enhancers like Vitamin C.
High-Fiber Diets: Large amounts of fiber can slow the absorption of iron.
Excessive Cow's Milk Consumption: Infants and young children who consume too much cow's milk may be at risk because milk is low in iron and can interfere with the absorption of iron from other foods.

Impaired Iron Absorption

Sometimes, the body struggles to absorb iron from food, even with sufficient intake.

Intestinal Disorders: Conditions that damage the small intestine lining, such as celiac disease and IBD, impair the body's ability to absorb iron.
Gastric Surgery: Procedures like gastric bypass surgery can remove or bypass the part of the intestine where iron is absorbed, leading to malabsorption.
Acid-Reducing Medications: Chronic use of antacids and proton pump inhibitors can decrease stomach acid, which is needed for iron absorption.

Increased Iron Needs

Certain life stages and activities require a higher iron intake than usual.

Pregnancy: The body's blood volume increases dramatically during pregnancy, and iron is needed for fetal growth, requiring higher intake to prevent deficiency.
Infants and Children: Infants and children need more iron during periods of rapid growth. Their initial iron stores from the mother can run out, necessitating iron-fortified foods or supplements.
Endurance Athletes: High-impact sports can cause iron loss through sweat, urine, and exercise-induced gastrointestinal bleeding.

Chronic Disease and Inflammation

Long-term health conditions can interfere with iron metabolism and lead to deficiency.

Anemia of Chronic Disease: Conditions like cancer, HIV/AIDS, autoimmune diseases (e.g., rheumatoid arthritis), and kidney failure can cause inflammation. The body's inflammatory response releases hepcidin, a hormone that blocks iron transport, reducing its availability.
Kidney Disease: The kidneys produce erythropoietin, a hormone that stimulates red blood cell production. In end-stage kidney failure, insufficient erythropoietin contributes to anemia.

Heme vs. Non-Heme Iron Comparison


Feature	Heme Iron	Non-Heme Iron
Source	Meat, poultry, and fish.	Plants (fruits, vegetables, grains, nuts), fortified foods, and supplements.
Absorption Rate	High, up to 40%.	Lower, between 2% and 10%.
Bioavailability	Readily absorbed by the body.	Absorption is affected by other dietary components, both enhancers and inhibitors.
Absorption Enhancers	Not significantly needed; its structure allows for easy absorption.	Vitamin C (citrus fruits, leafy greens) and meat/fish can significantly increase absorption.
Absorption Inhibitors	Less affected by other foods.	Phytates (grains, legumes), calcium (dairy), tannins (tea, coffee) can inhibit absorption.

Conclusion

Iron deficiency is a complex issue with multiple potential causes that extend beyond simply not eating enough iron. While a poor diet is a factor, chronic blood loss, impaired absorption due to medical conditions, higher physiological demands, and underlying inflammation from chronic diseases are equally important drivers. Identifying the specific cause is crucial for effective treatment. Seeking medical advice is essential to determine the root cause, as supplementation alone may not be a long-term solution if an underlying health condition is not addressed. Regular screening is recommended for high-risk populations, including pregnant women, young children, and frequent blood donors. By understanding the full picture of what can cause iron deficiency, you can take proactive steps to protect your health.

For more comprehensive health information, you can visit the World Health Organization website.

Frequently Asked Questions

Iron deficiency occurs when the body's iron stores are low. If this state is left untreated, it progresses to iron deficiency anemia, which is characterized by a low hemoglobin concentration and inadequate red blood cell production.

Vegetarian diets contain only non-heme iron, which is less efficiently absorbed than heme iron from animal products. While careful planning can provide enough iron, vegetarians must eat more iron and combine it with absorption enhancers like Vitamin C to prevent deficiency.

During pregnancy, a woman's blood volume increases, and iron is needed for both the mother and the developing fetus. This raises the body's iron requirements, making deficiency a risk if supplements are not taken.

Yes, chronic use of certain medications, such as nonsteroidal anti-inflammatory drugs (NSAIDs) like aspirin, can cause internal bleeding that leads to iron loss. Acid-reducing drugs can also impair iron absorption.

Intestinal conditions such as celiac disease and inflammatory bowel disease (IBD) can damage the lining of the small intestine, impairing its ability to absorb iron from digested food.

Yes, frequent blood donation causes a loss of iron with each donation. Regular donors may need to pay special attention to their iron intake through diet or supplements.

Chronic inflammatory diseases, such as autoimmune disorders or cancer, can cause the body to produce a hormone called hepcidin. Hepcidin blocks the absorption and release of iron, leading to a functional iron deficiency known as anemia of chronic disease.