June 2014 IssueUncovering Hidden Sources of Gluten — What Clients and Patients Must Know
By Megan Tempest, RD
Today’s Dietitian
Vol. 16 No. 6 P. 18

Jaime’s naturopathic doctor recently diagnosed her with nonceliac gluten sensitivity, a disorder characterized by an adverse food-induced reaction to gluten-containing foods. Adopting a gluten-free diet alleviated her chronic symptoms, such as bloating, diarrhea, and frequent migraines. But Jaime’s symptoms occasionally recurred because she unknowingly consumed gluten hidden in a wide variety of the foods she ate.

Eighteen million Americans are estimated to have nonceliac gluten sensitivity, six times the number of Americans who have celiac disease, an autoimmune disorder in which the ingestion of gluten damages the lining of the small intestine.1 Research has shown that, to maintain good health, individuals with celiac disease must eliminate gluten from their diets. They, too, are affected by eating hidden food sources of gluten.

However, unlike celiac disease, nonceliac gluten sensitivity is far less understood. It’s thought to be immune mediated, but no definitive test exists for proper diagnosis. People with nonceliac gluten sensitivity may experience bloating, diarrhea, and constipation—symptoms similar to irritable bowel syndrome—along with fatigue, headache, and bone or joint pain.2,3

“In the nonceliac gluten-sensitive population, we don’t know if some people are more sensitive than others, if some have more severe gastrointestinal responses, or what the long-term ramifications are of consuming gluten. We haven’t identified the biomarkers yet,” says Marlisa Brown, MS, RD, CDE, author of Gluten-Free, Hassle Free. The lack of evidence makes it difficult to know whether a person with nonceliac gluten sensitivity can safely ingest small amounts of gluten periodically or if complete abstinence is necessary, she says. However, because eating foods containing gluten can cause gastrointestinal (GI) symptoms for many people with nonceliac gluten sensitivity, they should abstain from eating them and learn where gluten hides in certain foods, especially when eating at restaurants.

Gluten is the protein found in wheat, rye, barley, and triticale, a grain grown specifically to have wheatlike qualities.4 To make shopping easier for consumers who must eat a gluten-free diet, many manufacturers have introduced gluten-free versions of staple pantry items such as pastas, crackers, and breads. And these products now are or will be clearly marked as gluten free on their packaging by August to meet the FDA’s new gluten-free labeling requirements, which include a standardized definition of gluten free on labels.

Foods must contain fewer than 20 parts per million (ppm) of gluten to be called gluten free. However, even diligent consumers who eat in restaurants accidentally may consume gluten that’s hidden in numerous foods, so it’s important they know which foods and types of products have gluten that they wouldn’t think contain the protein. The following is a discussion of the top six sources of hidden gluten dietitians can share with clients and patients.

Top 6 Sources of Hidden Gluten
1. Sauces, marinades, and gravies: Gluten may be present in gravies thickened with flour or in those flavored with soy sauce or malt vinegar. Soy sauce is a common ingredient in many marinades and sauces served in restaurants and sold in grocery stores. “Soy sauce contains more than just soybeans,” says Rachel Begun, MS, RDN, CDN, a food and nutrition consultant, media spokesperson, and blogger at The Gluten Free RD. “Most brands are made with wheat, so choose gluten-free soy sauce or naturally gluten-free tamari instead.”

Moreover, wheat flour traditionally is mixed with butter to form a roux that becomes the base for many cream sauces and gravies, so clients must be aware of this.

2. Processed meats: Sausages, meatloaf, meatballs, and other ground meats often contain wheat-based fillers. Breadcrumbs may be added to hamburger patties to bind the meat and improve texture. Hamburgers made from scratch with meat labeled “100% ground beef” wouldn’t contain gluten; however, many preformed patties, such as those served at restaurants, may contain wheat.

“Imitation crab meat found in prepared seafood salads and California-style sushi rolls may contain gluten,” Brown adds.

And processed deli meats also may harbor hidden gluten by way of cross-contamination. “Deli meats purchased at the deli counter may be gluten free, but the slicer is likely to be contaminated,” Begun says.

3. Vegetarian meat alternatives: Many vegetarian meat alternatives, such as veggie burgers and vegetarian sausages, are made with seitan, also known as wheat gluten. Others are made with gluten-containing flours or breadcrumbs that act as binders. And while tofu in its unadulterated form is gluten free, the fried tofu served in restaurants may be fried in a gluten-containing batter or marinated in a soy sauce that contains wheat. Moreover, imitation bacon typically contains gluten.

4. Soups: Noodles and barley are common soup ingredients that contain gluten. Less obvious to the average consumer is the gluten found in cream soups that have been thickened with flour. Begun suggests clients read labels thoroughly when purchasing these products. “Packaged stock, bouillon, and soup bases often contain gluten,” she adds.

5. Processed potatoes: Whole potatoes found in the produce department in supermarkets are gluten free, but potato chips and fries can be hidden sources of gluten. Potato chips may be seasoned with malt vinegar or contain wheat starch.

Begun offers two reasons to be cautious of French fries: “Restaurants often purchase frozen French fries, which may have a wheat-containing coating on them to help them fry up crispier. Secondly, the fryer they’re fried in is contaminated if it’s used to fry other items with breading or flour.”

6. Restaurant scrambled eggs and omelets: Pure, unadulterated eggs are inherently gluten free; however, restaurants may add pancake batter to eggs to bulk them up and produce a fluffy texture. Furthermore, even if the egg mixture is gluten free, it likely contains gluten from having been cooked on the same grill as a gluten-containing food such as pancakes, Begun says.

Code Words for Hidden Gluten
Clients and patients who must eliminate gluten from their diets not only must become aware of the many foods in which gluten can hide, but they also must learn the names of ingredients that masquerade as gluten on ingredient lists. Code words such as “fried,” “coated,” “crispy,” or “crusted” should raise a red flag, alerting clients that the food may contain gluten, Begun says, noting that these descriptors in particular may indicate the food is coated in a breading or gluten-containing flour before it’s fried.

Moreover, the method by which these foods are cooked increases the risk of cross-contamination. “The chips for the chips and guacamole may be 100% gluten free,” Begun says, “but most restaurants fry them for extra crispiness. If other items containing gluten were fried in the fryer, the chips aren’t safe to eat.”

Malt is another code word that Begun recommends her clients avoid. “Malt in the form of malt extract, malt syrup, malt flavoring, and malt vinegar is indicative of barley, a gluten-containing grain that doesn’t have to be identified in common terms on labels as gluten or barley,” she explains.

Brown advises consumers to exercise caution when buying or ordering Asian-style foods. “These foods may contain wheat from soy sauce and rice vinegars. Even some sticky rice may have starch added to it,” she says.

Gluten-Free Labeling
Last August, the FDA established a final rule that standardizes the definition and labeling requirements for gluten-free products for food manufacturers, imported foods, and restaurants; the deadline for compliance is August 2014.

The final rule states that a food may be labeled as gluten free if it’s either inherently gluten free or doesn’t contain an ingredient that’s a gluten-containing grain (eg, barley, rye, spelt wheat) or derived from a gluten-containing grain that has been processed to remove the gluten (eg, wheat starch) and the use of that ingredient results in the presence of 20 ppm or fewer of gluten in the food. In addition, the FDA rule states that any unavoidable presence of gluten in the food, such as what’s present from cross-contamination, must be less than 20 ppm.5

A study published in the June 2010 issue of the Journal of the American Dietetic Association examined the potential for cross-contamination of inherently gluten-free grains at food processing plants. Researchers sent 22 unopened, inherently gluten-free grains, seeds, and flours to a company that specializes in gluten analysis. Researchers found that seven samples of inherently gluten-free grain products contained mean gluten levels of 20 ppm or higher, and therefore wouldn’t be considered gluten free under the FDA rule for gluten-free labeling. The study raises the issue that if foods aren’t processed in a separate facility designated for gluten-free foods, products can potentially become contaminated with gluten, making it even more important for consumers to look for products that carry the gluten-free label.6

Empowering Clients and Patients
The FDA’s ruling certainly will help consumers more accurately identify gluten-free products, while giving restaurants and food manufacturers firm guidelines to follow. But consumers’ responsibility to speak up and ask questions can’t be overstated. “They have to learn how to ask the right questions and use their best judgment because they can’t rely on the restaurant cooks or the waitstaff to ensure their meal is gluten free,” Brown says. “Sometimes the waitstaff is more or less helpful, depending on their level of knowledge. Even the restaurants with a gluten-free menu may not even know what they’re doing.” For instance, restaurants unknowingly may cross-contaminate their plain vegetables by cooking them with pasta water, Brown explains.

“For a person to live in this society and remain socially active, they can’t be told they can only go to gluten-free restaurants, just as you can’t tell them to not attend Grandma’s holiday dinner because the stuffing contains gluten or that they can’t attend a child’s communion because the wafers have gluten. Doing so can really handicap a person and even cause depression,” Brown says, adding that RDs should focus on helping clients expand their choices and resources rather than limit them. “We should have a goal to help them enjoy their food and experiences as much as everyone else.”

— Megan Tempest, RD, is a dietitian at Boulder Community Hospital in Colorado and a freelance writer.


1. Non-celiac gluten sensitivity. National Foundation for Celiac Awareness website. http://www.celiaccentral.org/non-celiac-gluten-sensitivity. Accessed March 26, 2014.

2. What is non-celiac gluten sensitivity? National Foundation for Celiac Awareness website. http://www.celiaccentral.org/non-celiac-gluten-sensitivity/introduction-and-definitions. Accessed April 24, 2014.

3. What is non-celiac gluten sensitivity? The University of Chicago Celiac Disease Foundation website. http://www.cureceliacdisease.org/archives/faq/what-is-gluten-sensitivity. Accessed April 24, 2014.

4. Sources of gluten. Celiac Disease Foundation website. http://celiac.org/live-gluten-free/gluten-free-diet/sources-of-gluten. Accessed March 18, 2014.

5. How does FDA define ‘gluten-free’? US Food and Drug Administration website. http://www.fda.gov/forconsumers/consumerupdates/ucm363069.htm - gluten-free. August 2, 2013.

6. Thompson T, Lee AR, Grace T. Gluten contamination of grains, seeds, and flours in the United States: a pilot study. J Am Diet Assoc. 2010;110(6):937-940.