With celiac disease, you need to completely avoid gluten, a protein found in wheat, barley, and rye. Even small amounts can trigger an immune reaction that damages the lining of your small intestine. Research shows that as little as 50 milligrams of gluten per day (roughly a few breadcrumbs’ worth) is enough to cause intestinal harm, and some people react to even less.
The obvious sources are bread, pasta, and baked goods. But gluten hides in dozens of everyday foods you might not suspect, from soy sauce to salad dressings to certain candies. Here’s what to watch for.
Grains That Contain Gluten
Wheat is the biggest source of gluten in the Western diet, but it goes by many names. All of these are off-limits:
- Wheat varieties: spelt, kamut, farro, durum, semolina, einkorn, emmer
- Barley and anything made from it, including malt, malt extract, malt syrup, malt flavoring, and malt vinegar
- Rye
- Triticale (a wheat-rye hybrid)
If a grain name is unfamiliar, check whether it’s a wheat species. Ancient and “heritage” grains are trendy in health food circles, but spelt, farro, and kamut are all forms of wheat and contain just as much gluten as standard bread flour.
Common Foods With Hidden Gluten
Gluten often shows up as a thickener, binder, or flavoring ingredient in processed foods. These are the ones that catch people off guard most often:
- Sauces and gravies: Many use wheat flour as a thickener. Cream soups, cheese sauces, and roux-based gravies are frequent culprits.
- Soy sauce: Traditional soy sauce is brewed with wheat. Tamari (a Japanese variety made with little or no wheat) and coconut aminos are safe substitutes, but always check the label.
- Malt vinegar: Made from barley. It turns up in potato chip seasonings, salad dressings, and marinades.
- Brewer’s yeast: A byproduct of beer production, commonly found in supplements and some seasonings.
- Brown rice syrup: Sometimes made using barley enzymes, which can introduce gluten.
- Processed meats: Starch or dextrin listed on a meat or poultry product can come from any grain, including wheat.
Wheat starch can also appear in products labeled “gluten-free” only if it has been processed to contain less than 20 parts per million (ppm) of gluten, the threshold set by the FDA for gluten-free labeling. If it hasn’t been processed to that standard, it’s not safe.
Beer, Alcohol, and Beverages
Beer is the main alcoholic drink to avoid. Standard beer, ale, porter, and stout are all brewed with malted barley and contain gluten. Gluten-reduced beers, which are made with barley malt and then treated with enzymes, are not considered safe either. Current testing methods can’t reliably confirm that the gluten has been fully removed.
Wine, hard cider (without malt), and distilled spirits are generally safe. Distillation separates alcohol from proteins like gluten, so pure vodka, gin, whiskey, rum, brandy, and tequila are considered gluten-free even when made from wheat or barley. The exception is flavored spirits: if a gluten-containing ingredient is added after distillation, it’s no longer safe.
Watch out for flavored hard lemonades, wine coolers, and some hard ciders. If they contain malt or hydrolyzed wheat protein, they’re not gluten-free. Sake can also be a problem when it’s brewed with barley malt.
The Oats Question
Oats themselves don’t contain the same type of gluten found in wheat, barley, and rye. The problem is that commercial oats are frequently processed alongside gluten-containing grains, so cross-contamination is extremely common. Only oats specifically labeled “gluten-free” are recommended for people with celiac disease.
Even with certified gluten-free oats, guidelines from the American College of Gastroenterology suggest introducing them cautiously. Health Canada recommends waiting until you’ve been on a strict gluten-free diet for at least six months and all symptoms, including weight loss and growth issues, have resolved before trying them. Some people with celiac disease still react to oats regardless of contamination, so monitoring is important.
Why Even Tiny Amounts Matter
When you have celiac disease, gluten triggers your immune system to attack the lining of your small intestine. Immune cells flood into the intestinal wall, gradually destroying the tiny finger-like projections (villi) that absorb nutrients from food. Without those villi, your body can’t properly digest or absorb what you eat.
A systematic review by the UK Food Standards Agency found that consuming 200 milligrams or more of gluten daily clearly caused intestinal damage. Amounts as low as 34 to 36 milligrams daily didn’t cause visible damage in most studies, but in at least one study, just 1.5 milligrams daily was enough to trigger symptoms. For context, a single slice of wheat bread contains roughly 3,000 to 4,000 milligrams of gluten. The current clinical recommendation is to keep daily intake below 50 milligrams, which in practical terms means strict avoidance.
The good news is that the intestine can heal. More than 80% of patients see their diarrhea improve within 60 days of starting a strict gluten-free diet. Full mucosal healing takes longer, with a median time of about three years.
Cross-Contamination at Home and Out
You can eat entirely gluten-free ingredients and still get exposed if your food touches a surface, utensil, or cooking medium that has contacted gluten. In a shared kitchen, the highest-risk items are:
- Toasters: Crumbs from regular bread linger inside. Use a separate toaster for gluten-free bread, or place items on foil in a shared toaster oven after cleaning the rack.
- Deep fryers and cooking oil: If the same oil was used to fry breaded items, anything cooked in it afterward picks up gluten.
- Grills: Residue from buns or marinades stays on grill grates. Use aluminum foil or a cast iron skillet as a barrier.
- Colanders and strainers: Draining regular pasta and then gluten-free pasta in the same colander transfers gluten. Use separate ones or wash thoroughly between uses.
- Pizza stones: These are porous and trap flour particles. Keep a dedicated stone for gluten-free baking.
Eating out is trickier. Restaurants that serve both gluten-free and regular menus may use the same prep surfaces, fryers, or pasta water. Asking specifically about preparation, not just ingredients, helps you identify risk.
Reading Labels Effectively
In the United States, any product labeled “gluten-free” must contain less than 20 ppm of gluten. That’s the FDA standard, and it applies to claims like “no gluten,” “free of gluten,” and “without gluten” as well. This threshold is considered safe for the vast majority of people with celiac disease.
Products without a gluten-free label require closer reading. Look for wheat, barley, rye, malt, and brewer’s yeast in the ingredient list. Wheat must be declared as an allergen on US food labels, but barley and rye are not required to be called out separately. That means malt flavoring derived from barley might appear without the word “barley” next to it. When in doubt, contact the manufacturer.
Gluten detection devices you can use at home are currently not recommended by the American College of Gastroenterology. They produce too many false positives and false negatives to be reliable.
What You Can Eat
The list of naturally gluten-free foods is far longer than the restricted list. Rice, corn, quinoa, millet, buckwheat (despite the name, it’s not related to wheat), sorghum, amaranth, and teff are all safe grains and pseudograins. All fresh fruits, vegetables, meat, fish, eggs, dairy, legumes, nuts, and seeds are naturally gluten-free. Potatoes in every form are fine, as long as they’re not coated in flour or fried in contaminated oil.
For condiments, tamari (labeled gluten-free), coconut aminos, fish sauce, and liquid aminos all serve as safe replacements for soy sauce. Most plain mustards, vinegars other than malt vinegar, and hot sauces are safe. The gluten-free product market has expanded dramatically, so finding substitutes for bread, pasta, crackers, and baked goods is easier than it used to be.