Australian researchers have made a groundbreaking discovery showing that even extremely small amounts of gluten can trigger measurable immune activation in people with treated coeliac disease – findings that could help refine international food labelling standards.
Due to the prior lack of information in this area, international food labelling regulations vary, with allowable amounts of gluten in manufactured foods declared “gluten-free” in Australia and New Zealand differing to what is deemed safe in Europe and the United States.
Published today in Gastroenterology, the landmark study conducted at Wesley Research Institute in Brisbane, is the first to precisely measure immune responses to micro-doses of gluten using an advanced biomarker known as interleukin-2 (IL-2).
Researchers found that a gluten dose as low as 3 milligrams activated the immune system in some participants. The study was also able to define an “eliciting dose” of gluten that does not result in immune activation for 99% of people with coeliac disease.
The randomised, double-blind, placebo-controlled trial involved administering 153 gluten or placebo challenges to adults with coeliac disease who had maintained a strict gluten-free diet for more than two years. Participants received carefully controlled gluten or placebo doses ranging from 1000mg (about a third of a piece of bread) down to 1mg (less than a breadcrumb) with each challenge separated by four weeks.
Dr James Daveson, Director of the Coeliac Disease and Immune Health Research Program at Wesley Research Institute and lead author, said the study provided the clearest data yet on how the immune system reacts to trace amounts of gluten.
This is the first time we’ve been able to demonstrate, with certainty, that even very small gluten exposures can activate the immune system in people with coeliac disease.
Dr Daveson
“While we haven’t shown that these tiny doses cause long-term intestinal damage, the findings suggest that immune activation, similar to that seen with higher doses of gluten ingestion, may occur at levels currently permitted under many international gluten-free labelling standards.”
Packaged foods labelled “gluten-free” in Europe and the United States allow a concentration of up to 20 parts per million (ppm) of gluten, which equates to roughly 5mg of gluten in a 250 gram meal labelled gluten free. By contrast, Australia and New Zealand’s “no detectable gluten” rule typically keeps exposure below 0.75mg for a similar meal, offering greater protection for most patients. Importantly, in this study, the researchers determined that gluten doses below 2.4mg did not result in immune activation in 90%, while doses below 0.8mg of gluten did not activate the immune system in 95% of people with coeliac disease.
“Our findings support the strength of Australia and New Zealand’s approach,” said Dr Daveson.
They also highlight the need for international collaborations to progress standards that ensure safe gluten exposure for everyone living with coeliac disease.
Dr James Daveson
While at very low doses participants did report increased fatigue and mild gastrointestinal symptoms following gluten challenges, there was no difference in symptoms to those receiving placebo.
“Concerningly while at higher doses patient can be very accurate at determining if they have been inadvertently exposed to gluten, these findings suggest that at very low doses some patients may not be able to accurately identify inadvertent gluten exposure.
Dr James Daveson
He said larger, multi-centre studies are now needed to confirm whether long-term exposure to such small doses could lead to intestinal damage.
The research was funded by Wesley Research Institute and Coeliac Australia, and conducted in collaboration with the University of Queensland, CSIRO Agriculture and Food, Edith Cowan University and The Walter and Eliza Hall Institute.
Read more about the study in a feature by The Australian.
Read the Publication in Gastroenterology
Daveson A, Craig E, Vitak A …A Randomized Double-Blind, Placebo-Controlled Dose-Response Study to Assess the Gluten Threshold Dose in Celiac Disease, Gastroenterology, 2026; DOI: 10.1053/j.gastro.2026.03.011