Treatment allocation

A computer-generated list of random numbers was used for allocation of participants. This list was prepared by the Pharmacy Department of Hospital Universitari Mutua Terrassa without any clinical involvement in the trial. Eligible patients were randomly assigned to 1 of 2 treatment groups. The study medication was packed in boxes, and consecutively numbered for each patient according to the randomization schedule. Patients received either 10 g gluten opaque sachets or identical placebo sachets twice daily for 6 months in a double-blind fashion. Participants continued on a GFD throughout the study, and were instructed to mix the gluten or placebo powder with foods (in soup, yogurt, or purees). The 10 g gluten sachets contained 8.1 g gluten, 0.3 g fibre, 1 g fat, and 0.6 g carbohydrate; the placebo sachets contained 10 g maltodextrin (Fagron Ibérica, SA; Terrassa, Spain). There was no FODMAP content in the two types of sachets. The gluten and placebo powders were slightly different in taste but patients ignore how the other formulation was, and it was not possible to recognize gluten containing ones.