Effect of gluten-free diet on glycemic regulation and gut microbiota in people with celiac disease
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Background: Celiac disease (CD) is a chronic autoimmune bowel disease in the small intestine, which is triggered by gluten exposure in genetic predisposed individuals. CD is one of the most common autoimmune diseases worldwide. Approximately 30-40% of the global population are genetically predisposed for CD. The estimated global prevalence is 0.5%-1%. Currently, a lifelong gluten-free diet is the only treatment. Studies have reported gluten-free products to have poorer nutritional quality compared to similar gluten-containing products. A suboptimal diet is one of the most important risk factors for developing metabolic diseases such as type 2 diabetes and cardiovascular disease. Furthermore, recent studies have shown that gut microbiota may affect metabolic regulation of the host. Research on the health effects of a gluten-free diet other than therapy for celiac disease is limited and inconsistent. Aim: The study aimed to investigate the effect of a gluten-free diet on glycaemic regulation and gut microbiota in people with CD. Method: This double-blind randomized control trial with a parallel arm design, lasted for four weeks. Thirty participants with celiac disease were given either optimised gluten-free products (high in fiber) or benchmark product. Glycaemic regulation and gut microbiota were measured by blood- and faecal samples before and after intervention. Measurement of blood glucose levels was performed fasting and at different times after an OGTT (0-120 min). Results: There was a tendency towards a reduction in postprandial blood glucose response (iAUC 0 - 120 minutes) after an OGTT in the experiment group compared with control group. Moreover, a significant decreased iAUC level within the experiment group after intervention was found. We found a significant increased level of Firmicutes in the experiment group compared with control group, and a tendency towards significant reduction in Bacteroidetes within the experiment group. Abundance of five microbial species were significantly increased when comparing experiment with control group, within control group abundance in nine microbial species were found to decrease after intervention. Conclusion: The results indicate that a GFD with increased dietary fibre may contribute to improve glycaemic regulation, as well as affecting the gut microbiota. However, future research is needed to describe the impact of optimised gluten-free products on glycaemic regulation and gut microbiota in people with CD.