Gluten May Be Lurking in 'Gluten-Free' Restaurant Food

Megan Brooks

October 08, 2018

PHILADELPHIA — Roughly one-third of "gluten-free" restaurant foods contain detectable amounts of gluten, and pizza and pasta dishes are the most likely to be contaminated, according to a new study.

"While we expected to find gluten in a large number of gluten-free restaurant foods, the magnitude of contamination was truly impressive," said Benjamin Lerner, MD, from the Celiac Disease Center at Columbia University Medical Center in New York City.

"Clinicians should warn their patients with celiac disease that there is significant risk of gluten exposure when dining out, even when selecting GF-labeled dishes," he told Medscape Medical News.

A gluten-free diet is the mainstay of therapy for celiac disease. Restaurants are offering more gluten-free options now than ever before, but although the US Food and Drug Administration regulates packaged foods claiming to be gluten-free, there is no similar oversight for restaurants.

Given the possibility of cross-contamination, eating out can be a source of risk and anxiety for patients, Lerner said here at the American College of Gastroenterology 2018 Annual Scientific Meeting.

Clinicians should warn their patients with celiac disease that there is significant risk of gluten exposure when dining out, even when selecting GF-labeled dishes.

Lerner and his colleagues analyzed data on gluten contamination in restaurant foods collected over an 18-month period by 804 people using a Nima portable gluten detection device.

Of the 5624 food items tested, 4732 (84%) were labeled gluten-free. But 32% of these foods contained gluten (at least 20 ppm).

"This study is particularly interesting in showing that there is some decent gluten cross-contamination, even when you think you're getting something that is gluten-free," Seth Gross, MD, from NYU Langone in New York City, who is chair of the ACG educational affairs committee, told Medscape Medical News.

Gluten in foods labeled gluten-free was more common in dinner foods than in breakfast foods (34% vs 27%).

Gluten-free pizza was the food most likely to be contaminated with gluten (53%; odds ratio [OR], 2.5; 95% confidence interval [CI], 2.0 - 3.2; P < .0001), followed by gluten-free pasta (51%; OR, 2.1; 95% CI, 1.5 - 3.1; P < .0001).

Foods labeled gluten-free in the western states were less likely to be contaminated than those in the northeastern states (OR, 0.80; 95% CI, 0.67 - 0.95; P = .01).

Long-Held Suspicions Confirmed

Although this study provides "much-needed" data on gluten contamination in restaurant foods, it is important to keep in mind that the findings are based on crowd-sourced data from users of a portable gluten sensor, Lerner pointed out.

The foods that users chose to test might not be representative of all gluten-free restaurant foods, he explained, and might have been tested specifically because of doubts about gluten-free status.

In the future, he said he hopes to investigate the mechanisms of gluten contamination in restaurant foods, as well as interventions to reduce its occurrence.

There is no such thing as a gluten-free diet.

"This is a very clever study that unfortunately confirms what we have long suspected, which is that there is no such thing as a gluten-free diet," said Daniel Leffler, MD, from the Celiac Center at Beth Israel Deaconess Medical Center in Boston, who was not involved in the study.

"The best patients can do, and lead anything close to a normal life, is a gluten-restricted diet. Depending on how sensitive a patient is to gluten, this may or may not be enough to provide adequate control of celiac disease," he said.

"Even today, it is often felt that celiac patients with ongoing active disease are 'cheating' or just need to 'work harder at the diet.' These data are convincing that gluten exposure is inevitable and that adjunctive approaches are needed," Leffler told Medscape Medical News.

The study had no specific funding. Lerner and Leffler have disclosed no relevant financial relationships. Two of the study authors report relationships with Nima Labs. Gross is a consultant for Olympus Corp.

American College of Gastroenterology (ACG) 2018 Annual Scientific Meeting: Oral abstract 8. Presented October 8, 2018.

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