Barley and rye are the two major grains that contain gluten but are not wheat. Several less obvious sources also carry gluten without any wheat in the ingredient list, including malt-based products, certain beers, brewer’s yeast, and triticale. If you’re avoiding wheat specifically (due to a wheat allergy, for instance) but not all gluten, these foods are fine. If you’re avoiding gluten entirely, these are the hidden sources most likely to trip you up.
Barley and Its Gluten Proteins
Barley contains a family of gluten proteins called hordeins. These are closely related to the gliadins and glutenins in wheat but are distinct proteins. Barley shows up in foods more often than most people realize, and it rarely gets flagged the way wheat does. In the U.S., barley is not one of the nine major allergens that must be declared on food labels, so it can hide under less obvious names.
The biggest source of hidden barley gluten is malt. Under FDA regulations, the word “malt” on a U.S. ingredient label means barley malt unless another grain is specified (like “corn malt”). That applies to malt extract, malt syrup, malt flavoring, and malt vinegar. All of these are derived from barley and contain gluten. Testing by Gluten Free Watchdog found barley malt syrup contains over 280 ppm of gluten, well above the 20 ppm threshold the FDA sets for “gluten-free” labeling. Foods that commonly contain malt include certain cereals, chocolate milk mixes, malted milkshakes, some granola bars, and flavored snack foods.
Rye and Its Gluten Proteins
Rye contains gluten proteins called secalins. Like barley’s hordeins, secalins trigger the same immune response in people with celiac disease as wheat gluten does. Rye is easier to spot on labels than barley since it tends to appear in recognizable forms: rye bread, rye crackers, pumpernickel (which is made from rye flour), and rye whiskey’s grain base. That said, rye flour sometimes appears in multigrain breads and crackers without prominent labeling, so checking ingredient lists matters.
Triticale: A Hybrid Grain
Triticale is a cross between wheat and rye, making it a gluten-containing grain from both parent lines. Its endosperm contains secalins inherited from rye along with proteins from its wheat parentage. Triticale is less common in grocery stores but shows up in some specialty breads, cereals, and animal feed. The FDA classifies it alongside wheat, rye, and barley as a gluten-containing grain.
Beer and Gluten-Reduced Beverages
Most traditional beer is brewed from barley, not wheat, making it one of the most common gluten-containing beverages people overlook. Even beers with no wheat in the recipe still contain barley-derived gluten. Some breweries now produce “gluten-reduced” beer by adding an enzyme during fermentation that breaks down gluten proteins. These beers must test below 20 ppm to carry the “gluten-reduced” label, but they legally cannot be called “gluten-free” because they started with gluten-containing ingredients. They also carry a warning label noting they still contain gluten. Truly gluten-free beers are brewed entirely from grains like sorghum, rice, or millet.
Brewer’s Yeast vs. Baker’s Yeast
Brewer’s yeast is a surprisingly potent source of barley gluten. It’s often made from spent yeast collected after beer brewing, which means it carries residual gluten from the barley it fermented with. One laboratory analysis found a brewer’s yeast nutritional supplement contained roughly 772 mg/kg of barley gluten. Products like Marmite and Vegemite, which are made from brewer’s yeast extract, can also contain significant residual gluten.
Baker’s yeast, by contrast, is typically grown on sugar cane or beet molasses and has never been in contact with gluten-containing grains. Nutritional yeast (the flaky supplement popular in vegan cooking) also tested below the gluten-free threshold in laboratory analysis. The key distinction: if a label says “brewer’s yeast,” treat it as a gluten source. If it says “nutritional yeast” or “baker’s yeast,” it’s generally safe.
Where Oats Fit In
Oats occupy a gray area. They contain a protein called avenin that is structurally similar to wheat gluten, but clinical studies confirm that oat consumption is safe for most people with celiac disease. The concern with oats is primarily contamination. Commodity oats are often grown, transported, and processed alongside wheat and barley, picking up gluten along the way. Certified gluten-free oats are handled in dedicated facilities and tested to confirm they fall below 20 ppm. Even among oat varieties themselves, a few cultivars produce avenin levels that cross-react with gluten testing antibodies above 80 ppm, though researchers believe these cross-reactive avenin proteins are not truly harmful to people with celiac disease.
Ancient Grains That Are Actually Wheat
One common point of confusion: several grains that sound like they might be wheat alternatives are, in fact, types of wheat. Spelt, emmer, farro, einkorn, kamut (khorasan wheat), and durum are all taxonomically classified as wheat by the American Association of Cereal Chemists International. Spelt has been cultivated since around 7,000 BC and is sometimes marketed as an ancient grain alternative, but it is a subgroup of modern wheat. Kamut is a trademarked brand name for khorasan wheat. If you’re looking for grains with gluten but no wheat, none of these qualify.
Reading Labels for Non-Wheat Gluten
The FDA requires foods labeled “gluten-free” to contain less than 20 ppm of gluten and to exclude wheat, rye, barley, and their crossbreeds (unless the ingredient has been processed to remove gluten and tests below the threshold). But here’s the gap: U.S. allergen labeling law only mandates disclosure of wheat, not barley or rye. That means a product could contain barley malt extract and only list it in the general ingredients, with no bold allergen warning.
Watch for these ingredient names that signal non-wheat gluten: malt, malt extract, malt syrup, malt flavoring, malt vinegar, barley flour, barley flakes, rye flour, brewer’s yeast, and triticale. In personal care products, look for hordeum vulgare extract (barley), secale cereale seed flour (rye), and malt extract. While gluten in lotions and shampoos doesn’t cause an intestinal reaction through skin contact alone, it can be a concern with lip products or anything that might be accidentally ingested.