The Effect of Fibre-Rich Gluten Free Products on Glycaemic Regulation, Gut Symptoms, and Targeted Gut Microbial Taxa in Women with Coeliac Disease: A Randomised Controlled Trial

Background: The only treatment for coeliac disease (CeD) is a gluten-free diet. Gluten-containing cereals constitute a major source of dietary fibre, raising concerns about fibre intake for individuals with CeD. Objective: The present study aimed to investigate the effect of pseudocereal-based, fibre-rich gluten-free products on glycaemic regulation in women with CeD. Secondary endpoints were changes in gut symptoms, targeted gut microbial taxa, and inflammatory and metabolic markers. Methods: This double-blind, randomised, controlled trial was conducted remotely and included 30 women with CeD. Participants were allocated to consume either pseudocereal-based, fibre-rich gluten-free products (experimental) or benchmark products (control) for three weeks. Before and after the interventions, participants underwent an oral glucose tolerance test (OGTT), reported gastrointestinal symptoms, and provided blood samples to analyse micronutrients, metabolic markers, and a satiety hormone, and faecal samples for targeted gut microbial taxa analyses. Results: There was no significant difference in the glycaemic response after the intake of fibre-rich products compared with control products. However, a significant reduction in glucose iAUC was observed within the experimental group (p = 0.049). There was no significant change in gut symptoms within or between groups, except for a reduction in diarrhoea in the control group compared with the experimental group. The abundance of five bacterial species was significantly decreased after intake of control products compared to experimental products. Conclusions: Pseudocereal-based, fibre-rich gluten-free products may be included in the diet for women with CeD without affecting gastrointestinal symptoms. Whether these fibre-rich products improve glycaemic regulation and exert effects via alterations in the gut microbiota needs to be further investigated.