One-third of food labeled 'gluten-free’ in restaurants actually contains gluten: study

Those trying to avoid gluten may want to use caution when ordering off the menu.

One-third of food labeled “gluten-free” in restaurants actually contains gluten, according to a new study.

The study, published in the American Journal of Gastroenterology, used data collected using a portable gluten detection device in 5,264 tests from 804 users over an 18-month period.

Tests were conducted using a gluten detection device called “Nema,” where users place a pea-sized sample in the capsule. The capsule lid grinds the sample, which is combined with an extraction buffer and moved to the test strip inside the capsule. A sensor then indicates if gluten is detected with a wheat symbol, indicating gluten is present, or a happy face, showing the food sample is gluten-free.

In the tests, gluten was detected in 32% of foods labeled “gluten-free” on restaurant menus.

Gluten is found in items like barley, oats, rye, triticale (a cross between wheat and rye) and wheat. When foods are labeled “gluten-free,” they must contain less than 20 parts per million of gluten, as per the FDA’s guidelines, according to the Mayo Clinic.

Despite the device used to detect the presence of gluten being highly sensitive, the study said the “findings raise a potential concern.”

For those with conditions like celiac disease —an immune response in the small intestine that prevents the absorption of some nutrients and causes intestinal damage and symptoms including diarrhea, fatigue, bloating, anemia and weight loss according to the Mayo Clinic — avoiding gluten is the main way to manage a person’s health.

“Restaurant-going can be a particularly challenging aspect of navigating the gluten-free diet. Since this study only included voluntarily uploaded results, it does not mean that 32% of dishes are unsafe for people with celiac disease. But the fact that certain foods and settings were more likely to have detectable gluten suggests that certain scenarios are more prone to gluten cross-contact,” Dr. Benjamin Lebwohl, the study’s lead author and director of clinical research at The Celiac Disease Center at Columbia University and director of quality improvement at the Division of Digestive and Liver Diseases.

Pasta and pizza were the foods that were most likely to test possible for gluten, with 50.8% of samples — more than half — yielding positive results. For pizza labeled gluten-free, 53.2% tested positive for gluten, while 50.8% of pasta samples contained gluten according to test results.

Time of day also affected the likelihood of a food to contain gluten when labeled “gluten-free." Breakfast food tested possible 27% of the time, while lunch food contained gluten 30% of the time, and dinner food tested positive in 34% of cases.

Food in the West was less likely than the Northeast to test positive for gluten when labeled as “gluten-free,” the study found.

The study showed a “substantial fraction of GF labeled restaurant foods contain detectable gluten.” The findings do not mean that one-third of dishes are unsafe, but they do present data that could be useful for those avoiding gluten — like people with celiac.