Patient Education2 min read

Iron-Deficiency Anemia and the Digestive System

Overview

Iron-deficiency anemia happens when the body does not have enough iron to make healthy red blood cells. In adult men and in women after menopause, the most common cause is slow, often unnoticed blood loss from the digestive tract, or poor absorption of iron. Because this can be the first sign of a significant digestive condition, finding the cause matters as much as replacing the iron.

Symptoms

Persistent tiredness and weakness

Pale skin

Shortness of breath or palpitations on exertion

Dizziness or headaches

Cold hands and feet, or brittle nails

Black or tarry stools, or blood in the stool, in some cases

Common Causes

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Slow bleeding from stomach or duodenal ulcers, gastritis, or erosions

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Bleeding from colon polyps or colorectal cancer

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Celiac disease, which reduces iron absorption in the small intestine

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Inflammatory bowel disease or other sources of chronic bleeding

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H. pylori infection or previous stomach surgery

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Regular use of anti-inflammatory painkillers such as aspirin or ibuprofen

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Heavy menstrual periods, pregnancy, or low dietary iron (more common in younger women)

Self-Care Tips

Do not start iron tablets on your own before the cause is investigated, as this may hide an underlying problem

Ask your doctor about gastroscopy and colonoscopy, and testing for celiac disease, if you are an adult man or a woman after menopause

Eat iron-rich foods such as red meat, poultry, fish, lentils, and leafy greens

Pair plant sources of iron with vitamin C-rich foods, and limit tea and coffee around meals as they reduce absorption

Tell your doctor about all medicines you take, especially aspirin, anti-inflammatories, and blood thinners

Follow up with repeat blood tests as your doctor advises to confirm the treatment is working

When to See a Doctor

See a doctor if you have been told you have low hemoglobin or low iron, or if you have unexplained fatigue and paleness. Seek care promptly for black or bloody stools, vomiting blood, chest pain, fainting, or marked shortness of breath. Any adult man or post-menopausal woman with iron deficiency should be evaluated by a gastroenterologist to look for the source.

How doctors investigate it

The evaluation starts with blood tests that confirm iron deficiency, usually including a complete blood count and ferritin. Your doctor will ask about diet, medicines, menstrual history, and any digestive symptoms or family history of bowel disease or cancer. Blood tests for celiac disease are commonly requested. A gastroscopy, with biopsies from the stomach and small intestine, and a colonoscopy are recommended for most adult men and post-menopausal women. If both are normal and anemia persists, further tests of the small intestine may be considered.

Treatment options

Treatment has two parts: treating the underlying cause and restoring iron stores. Depending on the findings, this may mean treating an ulcer or H. pylori, removing polyps, managing celiac or inflammatory bowel disease, or reviewing medicines that irritate the stomach. Iron is usually given by mouth for several months, and intravenous iron may be used when tablets are not tolerated or not absorbed. Blood tests are repeated to confirm recovery and to check that the anemia does not return.

Frequently Asked Questions

Why does anemia in a man or post-menopausal woman need endoscopy?

These groups rarely lose iron through diet or menstruation, so low iron often points to hidden bleeding or poor absorption in the digestive tract. Gastroscopy and colonoscopy can find treatable causes such as ulcers, polyps, celiac disease, and in some cases cancer, often at an early stage. Your doctor will decide which tests are appropriate for you.

Can I just take iron supplements?

Iron may be needed to restore your levels, but it should not replace finding the cause. Taking iron alone can improve the blood count while an underlying problem continues unnoticed. Start supplements under your doctor's guidance, ideally alongside or after the investigation.

Why is my iron still low even though I take supplements?

Common reasons include ongoing blood loss, celiac disease, H. pylori infection, or reduced stomach acid that limits absorption. Taking tablets irregularly or with tea, coffee, or calcium can also reduce absorption. Tell your doctor, who may recommend further testing or a different form of iron, including intravenous iron in selected cases.