New research suggests one-third of the “gluten-free” foods sold in U.S. restaurants contain gluten

One-third of the “gluten-free” foods sold in U.S. restaurants actually contain trace levels of gluten, new research suggests.

gluten-free foods contain gluten

In a recent study, more than 800 investigators set out to assess the true gluten content of dishes listed as gluten-free on menus across the US. Armed with portable gluten sensors, they tested for gluten levels that met or exceeded 20 parts per million, the standard cutoff for any gluten-free claim.

In 5,624 foods tested by volunteers, 84% were labelled 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.


The study found that some gluten-free foods were riskier than others. For example, more than half of all purportedly gluten-free pastas and pizzas had gluten, according to the study.

“As awareness of celiac disease and the gluten-free diet have increased in recent years, restaurants have sought to offer selections that are compatible with these restrictions,” said study author Dr. Benjamin Lebwohl. “But some establishments do a better job than others at preventing cross-contamination.”

“The fact that gluten was so often found in pizza suggests that sharing an oven with gluten-containing pizza is a prime setting for cross-contamination,” explainedLebwohl.

“Gluten-free pasta can be contaminated if prepared in a pot of water that was used to prepare gluten-containing pasta.”

gluten-free foods contain gluten

No federal oversight 

Although the U.S. Food and Drug Administration regulates packaged foods with gluten-free labelling, there’s no federal oversight of gluten-free claims in restaurants, said Lebwohl.

“These results underscore the need for education in food preparation at restaurants, and the need for diners to inquire about these precautions,” Lebwohl said.

Dietitian Lona Sandon agreed. Gluten contamination in restaurants has long “been a concern for those with celiac disease,” said Sandon, an associate professor of clinical nutrition at the University of Texas Southwestern Medical Center at Dallas.

“Restaurant kitchens are just not built to assure the prevention of gluten contamination,” Sandon said. A chef may easily set a gluten-free bun down on a cutting board that just had a wheat bun on it while trying to get food out quickly to the customer. Then again, staff may just not know what has gluten in it and what doesn’t, she added.

In the absence of federal enforcement at the restaurant level, it’s up to the person handling the gluten-free product to keep it from becoming contaminated, Sandon said.

The study is scheduled for presentation Monday at a meeting of the American College of Gastroenterology, in Philadelphia. Research presented at meetings is usually considered preliminary until published in a peer-reviewed medical journal.