Effect of Adopting a Gluten-Free Diet on Exposure to Arsenic and Other Heavy Metals in Children With Celiac Disease: A Prospective Cohort Study.

Introduction: Lifelong adherence to a gluten-free diet (GFD) is the primary treatment of celiac disease (CeD), a gluten-driven enteropathy. Concerns have been raised about increased exposure to arsenic from a GFD because rice, which naturally bioaccumulates arsenic, is commonly used as a substitute for gluten-containing grains such as wheat. We hypothesize that arsenic exposure increases in newly diagnosed children with CeD after they adopt a GFD.

Methods: This is a single-center prospective longitudinal cohort study of children (age 2-18 years) with elevated celiac serology who underwent a diagnostic endoscopy before initiation of a GFD between January and May 2022. The primary outcome was change in urinary arsenic concentration between endoscopy and after 6 months on a GFD.

Results: Of the 67 recruited participants, 50 had a biopsy diagnostic of CeD and were invited to continue the study. Thirty-five participants completed sample collection. Participants were from a middle-class, well-educated population that was predominantly White with presenting symptoms of abdominal pain (51%) and diarrhea (29%). After 6 months on a GFD, there was a significant increase in the median urinary arsenic concentration (3.3 µg/L vs 13.6 µg/L, P = 0.000004). In regression models, family history of CeD and Hispanic ethnicity were associated with having a higher urinary arsenic concentration after 6 months on a GFD.

Discussion: Children with newly diagnosed CeD have increased arsenic exposure shortly after transitioning to a GFD. While the arsenic levels were well below acutely toxic concentrations, the clinical impact of chronic exposure to mildly elevated arsenic levels is unknown.