Gluten-free diet and gut bacteria in celiac and wheat sensitivity
What it found
In people with celiac disease or non-celiac gluten/wheat sensitivity, a gluten-free diet changed gut bacteria and eased symptoms.
In healthy people, it lowered helpful Bifidobacteria and raised some harmful bacteria.
What they found
Studies in people
Healthy people on GFD
In healthy people, a gluten-free diet for one month lowered Bifidobacterium, Clostridium lituseburense, and Faecalibacterium prausnitzii, and increased Enterobacteriaceae and Escherichia coli. Another study found that a low-gluten diet for eight weeks lowered Bifidobacteria and butyrate-producers like E. hallii and A. hadrus.
Celiac disease and GFD
People with celiac disease had less Bifidobacteria and more harmful bacteria than healthy controls. A gluten-free diet helped restore the balance, but some harmful bacteria like Proteobacteria remained higher in those with persistent symptoms.
NCG/WS and GFD
In people with non-celiac gluten/wheat sensitivity, a gluten-free diet for four weeks changed gut bacteria and improved symptoms in most. A low FODMAP diet followed by a gluten-free diet also changed bacteria, with the gluten-free diet increasing Bacteroidaceae and decreasing Lachnospiraceae.
Transgenic wheat bread
In people with non-celiac gluten/wheat sensitivity, eating bread made from transgenic low-gliadin wheat increased anti-inflammatory bacteria like Roseburia and Faecalibacterium, and decreased pro-inflammatory Bacteroides and others.
Gut bacteria and gluten
Celiac patients had altered fecal gluten-degrading activity even on a gluten-free diet, linked to unbalanced gut bacteria. First-degree relatives of celiac patients also showed differences in gut bacteria compared to healthy controls.
What the authors conclude
“In healthy subjects, GFD causes the depletion of beneficial species, e.g., Bifidobacteria, in favour of opportunistic pathogens, e.g., Enterobacteriaceae and Escherichia coli.”
Also in their conclusions
- They conclude that in healthy subjects, a gluten-free diet causes the depletion of beneficial species like Bifidobacteria in favour of opportunistic pathogens like Enterobacteriaceae and Escherichia coli.
- They state that in celiac disease and non-celiac gluten/wheat sensitivity, a gluten-free diet has a positive effect on gastrointestinal symptoms by helping to restore the microbiota population and by lowering pro-inflammatory species.
- They advise that further studies are needed to improve knowledge of the effects that a gluten-free diet could exert on the bacterial species involved in celiac disease and non-celiac gluten/wheat sensitivity.
How it was done
The authors wanted to understand how a gluten-free diet changes gut bacteria in healthy people and in those with celiac disease or non-celiac gluten/wheat sensitivity, since gut bacteria play a key role in gut barrier function and immune response.
They reviewed studies published between January 2009 and December 2019 that looked at the effects of a gluten-free diet on gut bacteria in healthy adults, adults with celiac disease, and adults with non-celiac gluten/wheat sensitivity. The studies used stool samples, duodenal biopsies, and genetic sequencing to identify bacteria.
What it can’t tell you
- This is a review of studies in people, so it can show links between a gluten-free diet and changes in gut bacteria, but it cannot prove that the diet causes those changes.
- The studies included used different methods and looked at different groups, so the results may not apply to everyone.
- The long-term effects of a gluten-free diet on gut bacteria and health are not known from this review.
Who paid
- Funding
- Funded by Ministero della Salute (from the PubMed record).
- Conflicts
- The authors declare no conflict of interest.
- Authors work at
- St. Anna University Hospital, Italy; Massachusetts General Hospital-Harvard Medical School, USA; University of Ferrara, Italy
The paper
- Title
- Effect of Gluten-Free Diet on Gut Microbiota Composition in Patients with Celiac Disease and Non-Celiac Gluten/Wheat Sensitivity
- Type
- ReviewThe authors read earlier studies and describe what they found. It isn’t a new study.
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Caio G, Lungaro L, Segata N, et al (2020). Effect of Gluten-Free Diet on Gut Microbiota Composition in Patients with Celiac Disease and Non-Celiac Gluten/Wheat Sensitivity. Nutrients. doi:10.3390/nu12061832Free full textPubMed 32575561DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error