Serum alkylresorcinols as biomarkers of dietary gluten exposure in coeliac disease

Background: Therapy for coeliac disease (CD) mainly relies on following a gluten-free diet (GFD); however, a serum marker for gluten intake has yet to be established. Aim: To evaluate the utility of alkylresorcinol concentrations for detecting gluten intake in studies of human and mouse. Methods: Alkylresorcinol concentrations were compared among treated patients with coeliac disease (n = 34), untreated coeliac disease patients (n = 36) and controls (n = 33). Furthermore, seven additional coeliac disease patients whose serum samples were available at diagnosis and after GFD were evaluated. In mice studies, alkylresorcinol concentrations were compared in the serum of five mice fed a regular chow and 10 mice fed lifelong with a gluten-free chow. In addition, the effect of adding gluten on changes of alkylresorcinol concentrations was also evaluated. Results: Total alkylresorcinol concentrations were significantly lower in treated with coeliac disease [median (IQR), 3 (2–8) nmol/L], compared to untreated patients [median (IQR), 32 (11–74) nmol/L; P < 0.0001] or healthy controls [median (IQR), 54 (23–112) nmol/L; P < 0.0001]. Moreover, alkylresorcinol concentrations in coeliac disease patients significantly decreased after introduction of a GFD (median, 34 nmol/L at diagnosis vs. 5 nmol/L after GFD, P = 0.02). In the mice, median (IQR) total alkylresorcinol concentrations in serum samples of mice fed lifelong with a gluten-free chow was 1.8 (1.6–2.3) nmol/L, which was further significantly increased to 16 (11–22) nmol/L after 8 days of feeding with the gluten-free chow that had gluten added to it. (P = 0.008). Conclusion: Serum alkylresorcinol concentrations could be a useful marker for dietary gluten in coeliac disease.