By Elodie Vaz | Published on April 13, 2026 | 3 min read
Celiac disease is an
autoimmune condition triggered by gluten ingestion, leading to chronic
inflammation of the small intestine. This damage alters the intestinal mucosa
and impairs nutrient absorption. The only treatment is a strict gluten-free
diet, which generally controls symptoms but does not fully restore intestinal
function.
In this context,
increased fiber intake is often recommended to support digestion and gut
health. However, the effectiveness of this strategy may be limited by a
previously underestimated factor: the composition of the gut microbiome.
Understanding why
fiber alone is not enough
A study conducted by
McMaster University and published on March 31 in Nature Communications
aimed to evaluate the ability of patients with celiac disease to metabolize
dietary fiber, in relation to their microbiome.
The researchers
hypothesized that the benefits of fiber depend not only on intake but also on
the presence of bacteria capable of breaking it down.
“Initially, we thought
the problem was insufficient fiber intake. Then we discovered that people might
not have the right bacteria to use the fiber they are already consuming. Increasing fiber intake
alone will not solve the problem if underlying issues with its utilization are
not addressed,” explained Mark Wulczynski, first author of the study, in a
press release.
A combined clinical
and preclinical approach
To explore this
hypothesis, researchers analyzed the gut microbiome of three groups: newly
diagnosed patients, patients on a gluten-free diet for more than two years, and
healthy controls.
Samples of intestinal
fluid were examined to identify present bacteria and their genetic capacity to
degrade different types of fiber. These data were cross-referenced with dietary
fiber intake and objective markers derived from plant DNA detected in stool
samples.
In parallel, preclinical
models were used to assess the impact of different types of fiber on intestinal
healing, particularly inulin and resistant starch (Hylon VII).
A microbial deficit
limiting the effect of fiber
The results show that
patients with celiac disease have a significantly reduced capacity to
metabolize fiber in the small intestine. This alteration is linked to a
deficiency in bacteria from the Prevotellaceae family, which are
involved in fiber degradation, inflammation regulation, and mucosal healing.
This deficit was observed
both in newly diagnosed patients and in those on a long-term gluten-free diet,
suggesting a persistent microbiome alteration related to the disease itself.
Moreover, while most
participants—whether patients or healthy individuals—consumed less fiber than
recommended, celiac patients faced a double disadvantage: insufficient intake
and reduced capacity to utilize it.
Preclinical analyses also
revealed that not all fibers are equal. Inulin, found in foods such as bananas,
garlic, and chicory root, promoted intestinal healing by stimulating the
microbiome. In contrast, Hylon VII showed no significant effect on either the
microbiome or tissue repair.
Toward a symbiotic
therapeutic approach
According to Professor
Elena Verdu, senior author of the study,
“While a gluten-free diet
remains essential […], our findings suggest that future therapies may also need
to support the gut microbiome.” She added, “This opens the door to combining
dietary strategies such as fiber supplementation with probiotics capable of
metabolizing these fibers.”
This so-called symbiotic
approach—combining specific fibers with microbiome modulation—could help
restore more complete intestinal function.
By highlighting the
crucial role of bacteria in fiber utilization, this study calls for a
rethinking of nutritional recommendations in celiac disease. Beyond gluten
exclusion, future therapeutic strategies may rely on an integrative approach
targeting both diet and the intestinal microbial ecosystem.
Further research will be
needed to confirm these findings and determine whether restoring both
microbiome composition and fiber intake can sustainably improve symptoms and
intestinal healing.
Read next: Gut microbiome and neurodegeneration: a new therapeutic lever
About the Author – Elodie Vaz
Health journalist, CFPJ graduate (2023).
Élodie explores the marks diseases leave on bodies and, more broadly, on human life. A registered nurse since 2010, she spent twelve years at patients’ bedsides before exchanging her stethoscope for a notebook. She now investigates the links between environment and health, convinced that the vitality of life cannot be reduced to that of humans alone.
