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PHILADELPHIA -- One third of restaurant foods labeled gluten-free were found to be contaminated with gluten, with certain foods being particular culprits, according to research presented here.
In 5,624 foods tested by volunteers nationwide, 84% were labeled as gluten-free, yet 32% contained gluten at levels of at least 20 ppm, reported Benjamin A. Lerner, MD, of the Celiac Disease Center at Columbia University in New York City, who led the study.
Action Points
- Note that this study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.
And compared with for other foods, the highest rates of gluten contamination were seen for pizza, at 53.2% (OR 2.5, 95% CI 2-3.2, P<0.0001), and pasta, at 50.8% (OR 2.1, 95% CI 1.5-3.1, P<0.0001), Lerner said at the annual meeting of the American College of Gastroenterology (ACG).
"Restaurants are now offering gluten-free options more than ever before. The U.S. Food and Drug Administration regulates packaged foods claiming to be gluten-free, but no similar oversight exists for restaurants," he said. "Given the possibility of cross-contamination, eating out can be a source of risk and anxiety for many patients."
Strict adherence to a gluten-free diet is the mainstay of treatment for the autoimmune condition known as celiac disease, but little is known about the potential for contamination in restaurant foods. The availability of portable gluten detection devices, such as the used in this , now allows individuals to identify gluten in foods prepared in restaurants. The researchers therefore conducted a crowd-sourced evaluation over a period of 18 months in which 804 participants shared the results of their point-of-care testing.
The data were sorted according to time of day, region of the country, local median household income, type of restaurant, and specific foods. A total of 59% of the tests were performed during dinner, 46% in Western states, and 63% in the highest income quartile.
The presence of gluten in foods labeled gluten-free differed by meal, with 27.2% being at breakfast and 34% at dinner.
"We found that 32.2% of all foods tested detected gluten, and remarkably, the rate of gluten contamination was the same (30%) for foods that were specifically labeled gluten-free," Lerner said.
On a multivariate analysis, food labeled gluten-free consumed in the West was less likely to contain gluten than in the Northeast (30.2% versus 34.5%, OR 0.80, 95% CI 0.67-0.95, P=0.01). This may reflect a greater interest in gluten-free diets in that area of the country, he suggested.
Gluten contamination was found more often in quick-service restaurants such as McDonald's (33.3%) than in casual dining restaurants such as TGI Fridays (28.6%) or fast casual restaurants such as Chipotle (22.3%).
Along with the results for pizza and pasta, more than 30% of the tests were positive for beef, burgers, french fries, and desserts.
Lerner said the results of the study should be considered in light of the fact that the data were crowd-sourced, and that the foods chosen might not be representative of all restaurant foods labeled gluten-free. Those foods could have been chosen because of users' doubts about gluten contamination, he noted.
"In future research, we hope to investigate the potential mechanisms of gluten contamination in restaurant foods and identify interventions to reduce its occurrence."
Disclosures
Two co-authors reported financial relationships with Nima.
Primary Source
American College of Gastroenterology annual meeting
Lerner B, et al "Gluten contamination of restaurant food: Analysis of crowd-sourced data" ACG 2018; Abstract 8.