Coeliac Disease

Gluten-free doesn't mean gut bacteria fully recover

Coeliac disease is an autoimmune condition, affecting an estimated 1 to 2% of people worldwide, where eating gluten triggers an immune reaction that damages the small intestine. A systematic review pooling 13 studies and 212 patients on a gluten-free diet found their gut bacteria still differed from people who never had coeliac disease, with lower levels of Bifidobacterium, a generally beneficial bacteria group, persisting even after gluten was fully removed.

Source: Influence of Gluten-Free Diet on Gut Microbiota Composition in Patients with Coeliac Disease: A Systematic Review

A large study confirms it

A more recent study analysed gut bacteria from two Dutch groups: 128 treated coeliac patients against 106 controls, and separately 24 treated patients against 654 controls, using detailed genetic sequencing. Compared with IBS and inflammatory bowel disease as reference conditions, treated coeliac patients showed more variation between individuals in their gut bacteria, right down to the level of specific bacterial strains, suggesting the condition leaves a lasting mark on the gut microbiome that diet alone doesn't fully erase.

Source: High-resolution analysis of the treated coeliac disease microbiome reveals strain-level variation

How gut bacteria might trigger the reaction in the first place

Researchers have proposed several ways gut bacteria could be involved before diagnosis too. Some gut microbes produce enzymes that change how gluten fragments are broken down, potentially making them more likely to trigger an immune reaction. Others may affect how easily gluten fragments pass through the gut lining. Bacteria from the genus Bacteroides have been studied specifically for this reaction-changing effect, since some strains process gluten fragments differently than others. In children with coeliac disease, researchers also found reduced levels of protective antibodies coating certain gut bacteria, a sign of disrupted immune-microbe communication in the gut.

Source: Intestinal dysbiosis and reduced immunoglobulin-coated bacteria associated with coeliac disease in children

The gut looks different before symptoms even start

Some of the most striking evidence comes from babies who haven't developed coeliac disease yet. A study of 164 infants, all with a close relative with coeliac disease, tracked their gut bacteria from one week old. Infants with a higher genetic risk of developing coeliac disease already had lower levels of Bifidobacterium, a generally beneficial bacteria group, and higher levels of Bacteroides fragilis and Staphylococcus, well before any symptoms appeared. This suggests the gut microbiome isn't just reacting to coeliac disease once it starts, it may be part of the picture from the very beginning.

Researchers studying the small intestine of children with coeliac disease have even discovered entirely new bacteria species there. One, now named Prevotella jejuni, was identified and formally described for the first time directly from a child's coeliac-affected gut.

Source: Influence of Milk-Feeding Type and Genetic Risk of Developing Coeliac Disease on Intestinal Microbiota of Infants: The PROFICEL Study

Source: Prevotella jejuni sp. nov., isolated from the small intestine of a child with coeliac disease

What this means for you

Coeliac disease needs a formal diagnosis, usually blood tests and a small intestine biopsy, before starting a gluten-free diet, since testing is far less accurate once gluten is already removed. Once diagnosed, a strict gluten-free diet remains the only established treatment. Alongside that, a wider variety of gluten-free plant foods may help support the gut bacteria research suggests stay disrupted even on treatment. That's the same idea behind GutLab, everyday gut health starts with regularly feeding the microbiome a broad range of plant-rich ingredients.