It is estimated that 18 million Americans have “nonceliac gluten sensitivity” whereas 3 million are estimated to have diagnosed celiac disease — an autoimmune disorder where consuming gluten damages the lining of the small intestine.

However, unlike celiac disease, nonceliac gluten sensitivity cannot be found by definitive tests. Those with nonceliac gluten sensitivity often experience symptoms like bloating, diarrhea, constipation, fatigue, headaches and bone or joint pain and find relief when they exclude gluten products. Eating foods that contain gluten can cause gastrointestinal (GI) symptoms for many with nonceliac gluten sensitivity, so it’s advised that they should prevent consuming products with gluten — just like those with diagnosed celiac disease.

But, what is gluten? Gluten is the protein found in wheat, rye, barley and triticale. For quite some time, it was difficult for the public to know whether a product was gluten-free. Now, food manufacturers have introduced gluten-free versions of staples like pasta, crackers and breads and these products are easier to spot on the shelves with “gluten-free” on the labels. Despite efforts to follow a gluten-free diet, those who often eat at restaurants may be accidentally consuming hidden gluten; therefore, it’s important to know which foods may have gluten.

6 sources of hidden gluten

Sauces, gravies and marinades. Gluten may be found in gravies that are thickened with flour, which can be placed on restaurant items like mashed potatoes or country-style steak. Soy sauce is made with wheat (contains gluten) and is a commonly used ingredient in marinades. We tend to think of soy sauce when we eat Chinese food; however, soy sauce may be used to marinade steaks and to season vegetables. Often, cream sauces require a roux, which involves flour (gluten), so this would be an item to watch as well.

Processed potatoes. Whole potatoes found in the produce section of the grocery store are naturally gluten-free. However, potato chips and French fries can have hidden gluten! Potato chips may be seasoned with malt vinegar (contains gluten) so this would be an item to watch carefully. Often, restaurants will purchase frozen French fries which may have a wheat-containing coating on them to help them become crispy when cooked. The fryers in restaurants are often contaminated if they are used to fry other items that have breading or flour.

Processed meats. Meatballs, sausages and other ground meats often have wheat-based fillers as an ingredient — which contains gluten. Also, breadcrumbs, which may be added to hamburger patties or meatloaf purchased at restaurants, can contain gluten. Hamburgers made from scratch with “100-percent ground beef” on the label would not contain gluten; however, preformed patties (like those served at some restaurants) may contain wheat. Also, imitation crabmeat, found in some sushi rolls or prepared seafood salads, may contain gluten.

Restaurant scrambled eggs and omelets. Pure eggs are naturally gluten-free; however, restaurants may add pancake batter to “plump” them up as it creates a fluffy texture. Often, eggs are cooked on the same grill as other gluten-containing items (like pancakes); therefore, the eggs may be contaminated with gluten.

Vegetarian meat alternatives. Veggie burgers and vegetarian sausages are often made with “seitan” which is known as wheat gluten. Others can be made with gluten-containing flour or breadcrumbs to act as binders. Tofu is gluten-free naturally; however, fried tofu may have been fried in gluten-containing batter or marinated in soy sauce.

Soups. Barley is a common soup ingredient that contains gluten. Some cream soups may be thickened with flour, which contains gluten. Packaged stock, soup bases and bouillon contain gluten unless it is specified on the label.

If eliminating gluten from a diet is a priority, it’s important to become aware of the many foods where gluten can hide. It’s also important to become familiar with the names of ingredients that hide gluten in the ingredients list. Some restaurants offer gluten-free items; however, they may not be aware that cross contamination can then make that food item no longer gluten-free. It’s always important to ask about a concern over the ingredients of a food item, then make the best decision with that knowledge. For more information, check out celiac.org for helpful tips on identifying gluten-containing foods!

Ashley Corbett, MS, RD, LDN, is a registered dietitian with Vidant Wellness Center and Vidant Beaufort Hospital.