Celiac disease (CD) is an immune-mediated disorder where ingesting gluten (a protein found in wheat, barley, and rye) triggers an abnormal reaction that damages the small intestine lining in genetically susceptible individuals. Anemia is a medical condition characterized by a deficiency of red blood cells or a reduced amount of hemoglobin, which carries oxygen throughout the body. CD is a common and often overlooked cause of anemia, particularly when the root cause of the deficiency remains unexplained.
How Celiac Disease Affects Nutrient Absorption
The damage within the small intestine directly causes nutrient malabsorption in Celiac Disease. The inner surface of the small intestine is covered in millions of tiny, finger-like projections called villi, which are responsible for absorbing nutrients from digested food. These villi significantly increase the surface area available for the uptake of micronutrients, including iron, folate, and vitamins.
When a person with CD consumes gluten, the immune system launches an inflammatory attack against the small intestine lining. This chronic inflammation leads to the flattening and eventual destruction (atrophy) of the villi. The resulting reduction in surface area means that the damaged intestine cannot properly absorb nutrients, even if the diet contains adequate amounts. This impaired absorption process ultimately leads to nutritional deficiencies, which often manifest as anemia.
The Specific Anemia Types Linked to Celiac
Anemia in Celiac Disease results from micronutrient deficiencies caused by malabsorption. The most common form seen in newly diagnosed adults is Iron Deficiency Anemia (IDA), affecting up to 46% of patients. Iron is needed to produce hemoglobin and is primarily absorbed in the duodenum, the uppermost part of the small intestine often most severely damaged by CD, severely impairing its uptake. Iron deficiency leads to microcytic anemia, where red blood cells are smaller than normal and appear pale due to insufficient hemoglobin.
CD also commonly interferes with the absorption of Vitamin B12 and folate (Vitamin B9). These B vitamins are essential for the production and maturation of red blood cells within the bone marrow. Folate is absorbed in the upper small intestine, similar to iron, making its deficiency common in CD. Although Vitamin B12 is absorbed lower down in the terminal ileum, its deficiency is reported in up to 41% of untreated patients.
A deficiency in Vitamin B12 or folate leads to macrocytic or megaloblastic anemia. In this type, red blood cells are abnormally large and immature, reducing their ability to effectively transport oxygen. Patients may also have a mixed anemia, showing characteristics of both microcytic and macrocytic types due to simultaneous deficiencies. Furthermore, the chronic inflammation associated with untreated CD can contribute to an “anemia of chronic disease.”
Testing and Treatment for Celiac Related Anemia
Investigating anemia that does not respond to standard treatment or has no clear cause includes testing for Celiac Disease. Physicians order a complete blood count (CBC) to analyze red blood cell size and hemoglobin levels, along with specific blood tests to measure stored iron (ferritin), Vitamin B12, and folate levels. If these tests suggest a deficiency-related anemia, celiac-specific antibody tests are the next step in the diagnostic process.
The primary treatment for Celiac-related anemia is strict, lifelong adherence to a Gluten-Free Diet (GFD). Eliminating gluten halts the immune response, allowing the small intestine villi to regenerate and heal over time. This healing process restores the surface area, which improves the body’s ability to absorb nutrients from food. Clinical symptoms often begin to improve within weeks of starting the GFD, although full intestinal lining recovery can take several months.
While the intestine heals, supplementation is required to correct existing deficiencies. This may involve high-dose oral iron and folate supplements, or injectable Vitamin B12 in cases of severe or persistent deficiency. Ongoing monitoring of blood markers is necessary to confirm that nutrient levels are returning to normal and that the anemia has resolved, indicating the treatment is working.