How does celiac disease affect oral iron (Fe) absorption?

From the Guidelines

Celiac disease significantly impairs oral iron absorption, and adherence to a gluten-free diet is essential to improve iron absorption in patients with iron-deficiency anemia and celiac disease. For celiac patients with iron deficiency, I recommend starting with a gluten-free diet as the primary treatment, which allows intestinal healing and improved nutrient absorption 1.

Key Considerations for Iron Supplementation

• For iron supplementation, ferrous sulfate (325 mg) taken once daily between meals with vitamin C (such as orange juice) can enhance absorption, as taking iron more than once a day does not improve absorption but increases side effects 1.
• Many celiac patients may require alternative iron formulations like ferrous gluconate or ferrous fumarate, which may cause less gastrointestinal distress.
• If oral supplements aren't effective despite adherence to a gluten-free diet, intravenous iron preparations like iron sucrose or ferric carboxymaltose may be necessary, particularly in patients with impaired absorption due to prior gastric surgery, inflammatory bowel disease, or chronic kidney disease 1.

Mechanism of Impaired Iron Absorption

• The impaired iron absorption occurs because celiac disease damages the duodenum and proximal jejunum, which are the primary sites for iron absorption.
• The intestinal villi atrophy reduces the surface area available for absorption, and inflammation further impairs the transport mechanisms for iron.

Monitoring and Follow-up

• Regular monitoring of hemoglobin, ferritin, and iron saturation levels is essential to track response to treatment, with reassessment typically recommended after 4-8 weeks of supplementation.
• A response to oral iron supplementation is typically evident within 1 month of treatment, and if such a response is not seen, assessment for nonadherence, malabsorption, or ongoing blood loss exceeding iron intake is needed 1.

From the Research

Effect of Celiac Disease on Oral Iron Absorption

• Celiac disease (CD) can lead to a reduction in iron absorption due to the destruction of the proximal duodenum, where iron absorption primarily occurs 2.
• The most frequent extra-intestinal manifestation of CD is iron deficiency anemia (IDA), with a prevalence of 12-82% in patients with new CD diagnosis 2.
• Oral iron supplementation, typically in the form of ferrous sulphate, may have limited absorption in patients with active CD and unpredictable absorption in patients on a gluten-free diet (GFD) 2.

Impact of Gluten-Free Diet on Iron Absorption

• A GFD is associated with adequate management of IDA, and normalization from anemic state typically occurs after at least 6 months of GFD, with iron stores replenishing in up to 2 years 2.
• Removal of gluten from the diet leads to histological recovery and normalization of iron levels in the majority of patients 3.
• However, some patients may persist with anemia despite a GFD, with a prevalence of 17.8% in adult patients and 4.4% in pediatric patients after 8-10 years of GFD 4.

Recovery from Iron Deficiency Anemia

• Recovery from anemia can occur between 6 and 12 months on a GFD alone, as a consequence of normalization of histological alterations of the intestinal mucosa 5.
• A significant inverse correlation between increase of Hb concentrations and decrease of individual histological scores of duodenitis was observed in patients with CD on a GFD 5.
• Severe iron-deficiency anaemia associated with asymptomatic coeliac disease can be resolved with a strict gluten-free diet 6.