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 More than half of gluten-free pizza and pasta dishes tested in
restaurants were positive for the presence of gluten, and overall,
about one third of supposedly gluten-free foods had some gluten,
researchers report in the American Journal of Gastroenterology.
"The long-suspected problem of gluten contamination in restaurant
foods that has been reported by patients likely has some truth
behind it," said senior study author Dr. Benjamin Lebwohl, director
of clinical research at the Celiac Disease Center at New York
Presbyterian Hospital and Columbia University Medical Center in New
York City.
"We don't know how common it is. But our findings suggest that pizza
and pasta and foods served during dinner time are more likely to
have this problem."
Lebwohl often heard anecdotally from patients that they suspected
they had consumed gluten at restaurants, even though the foods they
ate were labeled gluten-free.
When he learned that the manufacturer of the portable Nima Gluten
Sensor had a stash of data submitted by restaurant patrons who used
the device to test foods they suspected, Lebwohl asked if he could
use the information in a study.
The company supplied what they had: 5,624 food tests performed by
804 users during an 18-month period. When the researchers analyzed
the data, they found that 32 percent of tests revealed gluten
contamination in dishes that were supposed to be gluten-free.
Gluten-free pasta samples were positive for the protein in 50.8
percent of tests, while gluten-free pizza turned out to contain
gluten in 53.2 percent of tests. Gluten was detected in 27.2 percent
of breakfasts, 29 percent of lunches and 34 percent of dinners.
Lebwohl admits there are a lot of limitations to the dataset. "The
people tested what they wanted to test," he said. "And the users
chose which results to upload to the company. They may have uploaded
the results that surprised them the most. So, our findings don't
mean that 32 percent of foods are unsafe."
Moreover, Lebwohl said, the Nima is very sensitive. To be labeled
gluten free in the U.S., a product must contain less than 20 parts
per million (ppm). But the device can detect levels as low as 5 to
10 ppm, which "most people would not consider to be clinically
significant. So, it's possible for a food to have less than 20 ppm
and still indicate that gluten is present."
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The Nima gluten detector, which sells for about $229 and uses
disposable $6 test strip capsules, displays a wheat symbol when it
detects gluten and a smiley face when it doesn't, the authors note.
It can upload results to the company via a smartphone app.
Lebwohl suspects that gluten-free foods are being inadvertently
contaminated. "If a gluten-free pizza is put in an oven with a
gluten-containing pizza, aerosolized particles could come in contact
with the gluten-free pizza," he said. "And it's possible that
cooking gluten-free pasta in a pot of water that had just been used
for pasta that contained gluten might result in contamination."
The solution, Lebwhol said, may be better education for food
preparers.
About 1 percent of Americans have celiac disease, Lebwohl said. The
amount of gluten needed to cause intestinal damage in these patients
is tiny, he added. "It would be barely visible, like tiny crumbs of
bread," he explained.
While the limitations of the data mean it's not possible to
determine what percentage of restaurant foods labeled gluten-free
actually contain the protein, "it's interesting to know that so many
foods marked as gluten-free aren't," said Therezia Alchoufete, a
clinical dietician in the University of Pittsburgh Medical Center's
Digestive Disorders Center.
"This is definitely a consideration for anyone with celiac disease
trying to eat outside of the home. At home they know they are
preparing foods without any gluten-containing items." The issue goes
beyond gluten, Alchoufete said. "This could apply to anyone who has
a sensitivity to a certain ingredient."
SOURCE: https://bit.ly/2JZT3zk American Journal of Gastroenterology,
online March 26, 2019.
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