Gluten, gut bacteria and coeliac disease
What it found
In people with coeliac disease, the gut and mouth bacteria differ from those in healthy people, and a gluten-free diet does not fully restore them.
Probiotics may help with symptoms, but the evidence is limited.
What they found
Studies in people
Mouth bacteria and gluten
People with coeliac disease have different mouth bacteria than healthy people. Their saliva breaks down gluten faster, and certain mouth bacteria can completely break down a hard-to-digest piece of gluten.
Gut bacteria differences
In people with active coeliac disease, gut bacteria are out of balance. Levels of Proteobacteria go up, while Firmicutes and Actinobacteria go down.
Bacteria break down gluten
Some gut bacteria can break down gluten. In one study, 85 out of 114 bacterial strains from the gut lining could grow on gluten, and some could break down a key immune-triggering piece.
Gluten-free diet and bacteria
A gluten-free diet does not fully fix the gut bacteria in people with coeliac disease. It also changes the bacteria in healthy people, lowering helpful types and raising others.
Probiotics and coeliac disease
Some small studies found that probiotics improved gut bacteria or symptoms in people with coeliac disease on a gluten-free diet. One 12-week trial found no change in gut bacteria.
Animal and lab studies
Animal study
In gluten-sensitive macaques, the variety and amount of gut bacteria were lower than in healthy macaques. Two bacterial families were more common in the gluten-sensitive animals.
What the authors conclude
“Probiotics may help to control symptoms in patients with CD adhering to a GFD, however, the data are limited and this could not be an absolute prediction.”
Also in their conclusions
- They say that the exact germ pattern in coeliac disease is not yet known, and the cause-and-effect link between gut bacteria imbalance and the disease is still unclear.
- They suggest that probiotics, especially Bifidobacterium and Lactobacillus, might help as an add-on for people with coeliac disease and reduce problems from a strict gluten-free diet.
- They advise that more high-quality trials are needed to find the best probiotic strains, timing and doses.
How it was done
Coeliac disease is on the rise, and the only treatment is a strict gluten-free diet, which is expensive and hard to stick to. The authors wanted to see whether gut bacteria could offer another way to manage the disease.
The authors pulled together existing studies on gluten, mouth and gut bacteria, and coeliac disease. These included studies in people with and without coeliac disease, and some animal studies.
What it can’t tell you
- This is a review of other studies, so it cannot prove that changes in gut bacteria cause coeliac disease or are caused by it.
- Many of the findings come from small studies, and the results are not consistent.
- The studies in animals cannot show what happens in people.
Who paid
- Conflicts
- No potential conflict of interest was reported by the author(s).
- Authors work at
- Affiliated Hospital of Nanjing University of Chinese Medicine, China
The paper
- Title
- Gastrointestinal microbiome and gluten in celiac disease
- Type
- ReviewThe authors read earlier studies and describe what they found. It isn’t a new study.
- Evidence
- Studies in people · animals · lab
- Summarised from
- Full text
- Cite
- Wu X, Qian L, Liu K, Wu J, Shan Z (2021). Gastrointestinal microbiome and gluten in celiac disease. Annals of medicine. doi:10.1080/07853890.2021.1990392Free full textPubMed 34647492DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error