One in 40 foods labelled as "gluten-free" in Australia's supermarkets isn't actually gluten-free, according to new research from the Walter and Eliza Hall Institute of Medical Research.
The study, published today in the Medical Journal of Australia (MJA), tested 256 of Australia's most popular gluten-free packaged foods and found that 2.5% contained the gluten protein.
The gluten-free label is monitored by Food Standards Australia New Zealand (FSANZ) and its code stipulates that all products using the label must have no detectable traces of the gluten protein.
This is particularly important for those who have coeliac disease, a condition that initiates an abnormal immune system response to the gluten protein, found in wheat, rye, barley, and oats.
Dr Jason Tye-Din, a researcher in coeliac disease from the Walter and Eliza Hall Institute, told BuzzFeed News that most foods labelled gluten-free are safe for coeliacs.
However, when the researchers retested different batches of the same gluten-free products that were found to contain gluten, they kept testing positive, which implies that some products are consistent offenders.
"It suggests that some processes could be improved by manufacturers. [It] suggests that it's not just a one-off thing, there's a process there," said Tye-Din.
A strict and lifelong gluten-free diet is the only treatment for coeliac disease and Tye-Din said his team was interested in conducting this research because even people who say they follow the diet "report symptoms or don't get the full healing of their bowel".
In 2008 the NSW Food Authority conducted a review of 211 products that claimed to be gluten-free and found that 4.7% tested positive for traces of gluten.
Tye-Din says the levels of gluten found in the foods in the MJA study were low and unlikely to cause harm to people suffering from coeliac disease.
The main offender was a gluten-free pasta that was found to have 3mg of gluten per serve; Tye-Din states that consumption of around 10mg of gluten for those with coeliac disease per meal is considered safe.
"The reality is, it's unlikely at these levels to be harmful, [but] it's something that tells us, 'Well, we've detected it, and it's not in line with the Australian standard' — so that does need to be improved," he said.
Another study led by Tye-Din published in the MJA earlier this year reviewed the adherence of Melbourne restaurants to gluten-free claims by sampling meals and found that 9% of supposedly gluten-free meals contained detectable amounts of gluten.
While Tye-Din is concerned about the manufacturing processes behind some gluten-free food, he says that "eating out is far riskier for gluten-free patients than eating pre-packaged food".