Celiac disease causes iron and zinc deficiency.

An extensive body of clinical and mechanistic evidence establishes a direct, causal chain from the immune-mediated pathogenesis of celiac disease to systemic nutrient depletion, specifically manifested as iron and zinc deficiencies.

Clinical and epidemiological evidence

• Iron deficiency and anemia: Depleted iron stores (low serum ferritin) are among the most common extraintestinal presentations of celiac disease. Clinical studies indicate that 30% to 60% of newly diagnosed pediatric and adult celiac patients present with iron deficiency, and unexplained iron-deficiency anemia is frequently the sole presenting clinical sign.
• Zinc deficiency: Clinical cohort studies demonstrate that zinc deficiency is highly prevalent at diagnosis, affecting up to 67% of newly diagnosed patients. Systematic reviews confirm that circulating zinc concentrations are significantly lower in untreated celiac patients compared to healthy controls.
• Recovery dynamics: Implementation of a strict gluten-free diet promotes mucosal healing and a gradual restoration of absorptive capacity. While hematological parameters typically improve within 12 months, replenishing systemic iron (ferritin) and zinc stores often takes longer, frequently requiring targeted oral supplementation.

Mechanistic explanations

• Immune-mediated mucosal damage: In genetically predisposed individuals (expressing HLA-DQ2/DQ8), dietary gluten peptides undergo deamidation by tissue transglutaminase. These modified peptides trigger a Th1-mediated inflammatory response and enterocyte apoptosis driven by cytotoxic intraepithelial lymphocytes. This results in progressive villous atrophy, crypt hyperplasia, and structural flattening of the mucosa (Marsh classification).
• Impaired proximal absorption: Active transport of both iron (via divalent metal transporter 1, or DMT1) and zinc (via ZIP/ZnT transporter families) occurs predominantly in the enterocytes of the duodenum and upper jejunum. The severe anatomical destruction of these proximal villi reduces the functional mucosal surface area and downregulates these critical apical membrane transporters, leading directly to malabsorption.

Bottom line

Celiac disease is conclusively proven to cause proximal small-intestinal villous damage and mucosal flattening. Because the duodenum is the primary site of absorption for iron and zinc, this structural damage directly impairs their uptake, commonly leading to iron deficiency (low ferritin) and zinc deficiency. Clinicians should routinely screen newly diagnosed patients for these micronutrient deficiencies and monitor their recovery alongside mucosal healing on a strict gluten-free diet.