The Impact of a Gluten Free Diet on Gut Microbiota & Intestinal Epithelial Barrier Function in Coeliac Disease

This 2020 study by Caio et al., titled “Effect of Gluten-Free Diet on Gut Microbiota Composition in Patients with Coeliac Disease”, investigates how adhering to a gluten free diet (GFD) influences the gut microbiota and Intestinal Epithelial Barrier Function of individuals with coeliac disease (CD).

The research emphasises that while the GFD is essential for mucosal healing in CD, its broader effects on gut microbial balance are equally critical yet often overlooked.

Key Findings:

• Gut Dysbiosis in Coeliac Disease: Patients with active CD displayed a disrupted gut microbiota composition, characterized by an overrepresentation of pro-inflammatory bacteria such as Proteobacteria and a reduction in beneficial strains like Bifidobacteria and Lactobacilli.

• Positive Shifts with GFD: After 2 years on a strict GFD, patients showed significant improvements in their gut microbiota. There was an increase in microbial diversity and a partial restoration of beneficial bacteria, particularly Bifidobacteria.

• Incomplete Recovery: Although the GFD led to meaningful changes, the microbiota of CD patients did not fully match that of healthy controls. This suggests that while the diet helps, other therapeutic strategies (e.g., targeted prebiotics or probiotics) may be necessary to fully restore microbial health.

• Intestinal Permeability in Coeliacs: In coeliac disease (CD), gluten ingestion leads to increased intestinal permeability, or "leaky gut," caused by the overexpression of zonulin and the disassembly of tight junctions between intestinal cells. This allows gliadin peptides to cross the intestinal barrier, triggering systemic inflammation and immune responses in both the gut and other organs. This disruption in intestinal function is why many individuals with CD also experience symptoms of irritable bowel syndrome (IBS), as the altered gut permeability and inflammation can contribute to IBS-like symptoms.

Why This Matters for Gut Health:

Gut health is foundational to systemic health, influencing digestion, immune regulation, mental well-being and inflammation levels. In coeliac disease, damage to the intestinal lining and chronic inflammation disrupt the gut microbiota and gut wall integrity compounding the disease’s impact. This study confirms that restoring gut microbial balance is not only a byproduct but a key goal of dietary treatment.

When the gut microbiota is imbalanced (dysbiosis) and/or there is ongoing intestinal permeability, it can perpetuate symptoms like bloating, fatigue, constipation, or diarrhoea even after gluten removal. The partial restoration seen in this study underscores the need for a holistic gut-healing approach that goes beyond gluten elimination.

Conclusion:

This study affirms that a strict gluten free diet does more than heal the intestinal lining in coeliac disease, it actively reshapes the gut microbiota in a healthier direction. However, the incomplete normalisation of microbiota suggests that gut-targeted therapies should be integrated alongside dietary management. For practitioners and individuals managing coeliac disease, this means prioritising both nutritional adequacy and gut microbial support to achieve optimal long-term health.

Reference:Caio G, et al. Effect of Gluten-Free Diet on Gut Microbiota Composition in Patients with Coeliac Disease. Nutrients. 2020;12(6):1834. doi:10.3390/nu12061834.

You can read the full study HERE.