Gluten shows up in three grains: wheat, barley, and rye. Every food made from these grains contains gluten unless it has been specifically processed to remove it. That covers obvious staples like bread and pasta, but gluten also hides in dozens of less obvious products, from soy sauce to licorice to certain salad dressings.
The Three Grains That Contain Gluten
Wheat is by far the biggest source. It contains two proteins, glutenin and gliadin, in roughly equal amounts. Together they form gluten, the stretchy network that gives bread dough its chew and structure. Barley contains a related protein called hordein, and rye contains secalin. All three trigger the same immune response in people with celiac disease.
Wheat also comes in forms you might not immediately recognize as wheat. Spelt, kamut, farro, durum, semolina, and einkorn are all wheat varieties and all contain gluten. Triticale, a hybrid of wheat and rye, contains it too. If a grain name is unfamiliar, checking whether it belongs to the wheat family is a reliable first step.
Everyday Foods Made With Gluten
The most concentrated dietary sources are the staples built around wheat flour:
- Bread and baked goods: sandwich bread, rolls, bagels, muffins, croissants, tortillas, pizza dough, cakes, cookies, and pie crusts
- Pasta and noodles: spaghetti, penne, egg noodles, ramen, udon, and couscous (which is actually tiny pasta, not a grain)
- Breakfast cereals: most flaked, puffed, or granola-style cereals contain wheat or barley malt
- Battered and breaded foods: fried chicken, fish sticks, onion rings, and anything coated in flour before cooking
- Beer: brewed from barley or wheat, making conventional beer one of the most common liquid sources of gluten
Seitan: Pure Gluten as a Protein
Seitan is literally concentrated wheat gluten. It’s made by kneading wheat flour dough and then washing away the starch, leaving behind a dense, chewy mass of pure gluten protein. Sometimes called “wheat meat,” seitan has been used in Chinese Buddhist cooking for centuries and is now common in Western plant-based eating as a meat substitute.
Seitan also appears as an ingredient in many packaged plant-based products: meatless ground “beef,” deli slices, and sausages often use wheat gluten (sometimes listed as “vital wheat gluten”) to create a meaty texture. If you’re avoiding gluten, checking the ingredient list on any meat alternative is important, since not all of them are soy- or pea-based.
Hidden Gluten in Processed Foods
Gluten turns up in a surprising number of processed products where wheat serves as a thickener, binder, or flavoring agent rather than the main ingredient. These are the sources that catch people off guard:
- Soy sauce: traditionally brewed with wheat as a primary ingredient
- Teriyaki and other Asian sauces: typically built on a soy sauce base
- Malt vinegar: made from barley
- Creamy sauces and gravies: often thickened with a roux, which is flour cooked in butter
- Canned and boxed soups: many use wheat flour as a thickener
- Salad dressings: some contain wheat-based thickeners or malt ingredients
- Licorice candy: wheat flour is a standard ingredient in traditional licorice
- Seasoning blends: some use wheat-based carriers to hold spices together
A few common food additives also deserve attention. Dextrin, maltodextrin, and modified food starch can all be made from wheat, but they can also be made from corn, potato, or tapioca. U.S. labeling law requires that wheat be declared on the allergen statement, so checking that line on the package resolves the question quickly.
Where Oats Fit In
Oats are not a gluten-containing grain in the way wheat, barley, and rye are. They contain a different protein called avenin, which is present at much lower concentrations: 10% to 15% of the oat’s total protein, compared to 80% to 85% for gluten in wheat. Avenin also lacks the specific protein sequences that trigger celiac disease in wheat, barley, and rye, making true oat intolerance rare.
The real problem is contamination. Oats are frequently grown near wheat fields, transported in shared equipment, and milled in facilities that also process wheat and barley. U.S. grading standards for oats allow up to 2% foreign material, which could be entirely wheat and barley. This contamination can happen at every step, from seed purity to harvesting to final packaging. Oats labeled “gluten-free” are grown and processed under controlled conditions to stay below the 20 parts per million threshold. If you’re sensitive to gluten, choosing certified gluten-free oats is the only reliable option.
Alcoholic Drinks
Conventional beer is brewed from barley or wheat and contains gluten. Lagers, ales, stouts, porters, and wheat beers all fall into this category. Malt beverages like hard lemonades or malt coolers are also barley-based.
Distilled spirits, even those made from gluten-containing grains like rye whiskey or barley-based vodka, are generally considered safe. The distillation process removes proteins, including gluten, from the final product. One exception: flavored spirits. Flavoring gets added after distillation and can reintroduce gluten. Wine and cider are naturally gluten-free. Beers marketed as “gluten-removed” are a gray area. They start with gluten-containing ingredients and use enzymes to break down the protein, but current testing methods can’t reliably confirm how much gluten remains. Beers labeled “gluten-free” and made from naturally gluten-free grains like sorghum or rice are a safer choice.
Reading Labels in the U.S.
The FDA requires that any food labeled “gluten-free” contain less than 20 parts per million of gluten. That standard also applies to labels reading “no gluten,” “free of gluten,” or “without gluten.” To qualify, a product cannot contain any type of wheat, rye, or barley, or any ingredient derived from those grains that hasn’t been processed to remove gluten below the 20 ppm threshold.
For products that don’t carry a gluten-free label, the ingredient list and allergen statement are your tools. U.S. law requires wheat to be identified on the allergen statement, but barley and rye are not covered by the same requirement. That means you need to scan the full ingredient list for terms like barley, malt, malt extract, malt flavoring, rye flour, and brewer’s yeast (which is typically derived from barley).
Cross-Contact During Cooking
Sharing kitchen tools between gluten-containing and gluten-free foods is a common concern, but recent controlled experiments suggest the risk varies by situation. Shared utensils like spoons, colanders, knives, and even deep fryers did not lead to significant gluten contamination in lab settings. Cooking gluten-free pasta in the same water previously used for regular pasta, however, pushed gluten levels above the 20 ppm safety threshold. Using fresh water for gluten-free pasta is a simple, effective precaution.