People living with coeliac disease are often encouraged to increase their fibre intake to support gut health, either through diet or supplements. However, new research from McMaster University suggests fibre alone may not deliver the expected benefits unless the gut contains the bacteria needed to process it.
In a study published in Nature Communications in March 2026, researchers found that people with coeliac disease have a reduced ability to break down dietary fibre in the small intestine. This was linked to a shortage of fibre‑degrading bacteria, particularly from the Prevotellaceae family, which are known to support intestinal healing and help regulate inflammation. Importantly, this pattern was observed not only in newly diagnosed patients, but also in people who had followed a strict gluten‑free diet for many years, suggesting these microbiome changes are driven by the disease itself rather than diet alone.
The authors say these findings challenge the assumption that insufficient fibre intake is the primary issue. Instead, they point to a more complex problem: without the right gut microbes, adding more fibre may have limited benefit unless the body’s ability to use it is restored.
The researchers also examined whether some fibres are more helpful than others. Using preclinical models, they found that inulin, a naturally occurring fibre found in foods such as bananas, garlic, onions and chicory root, restored microbial activity in the small intestine and accelerated healing of gluten‑related intestinal damage. By contrast, a commonly used corn‑based resistant starch did not produce the same effect.
Together, the findings suggest that for people with coeliac disease, fibre type may matter as much as fibre quantity, pointing towards future treatment approaches that combine targeted dietary choices with microbiome‑focused therapies.
