Beer has gluten because its main ingredient, barley, is a gluten-containing grain. The proteins that make up gluten in barley survive the entire brewing process, from mashing through fermentation, and end up in your finished pint. Wheat and rye, two other gluten-containing grains, are also common in many beer styles.
Barley Is the Foundation of Most Beer
Barley is the base grain for the vast majority of beers brewed worldwide. It contains storage proteins called hordeins, which are barley’s version of gluten. Wheat contains its own gluten proteins (gliadins and glutenins), and rye contributes secalins. All of these are classified under the gluten umbrella because they share a similar molecular structure, and all of them can trigger an immune response in people with celiac disease or gluten sensitivity.
Barley is prized in brewing because it provides the sugars that yeast ferments into alcohol, along with the body, foam stability, and flavor that define beer. Wheat beers use a significant portion of wheat alongside barley, which dramatically increases gluten content. One study found that wheat beer contained roughly 6,000 mg/kg of gluten-related proteins, about a thousand times more than a standard lager at around 6 mg/kg.
Brewing Doesn’t Destroy Gluten
You might assume that boiling, fermenting, and filtering beer would break down gluten proteins. It doesn’t, at least not enough to matter. Gluten proteins are unusually tough. They’re insoluble in water and resist the heat and enzymatic activity of the brewing process.
During mashing, crushed barley is steeped in hot water to extract sugars. The temperatures involved (typically around 60 to 70°C) don’t break gluten apart. Boiling the resulting liquid, called wort, at 100°C still leaves gluten proteins largely intact. Fermentation happens at much lower temperatures, around 20°C for ales, and while yeast does modify some proteins through precipitation and aggregation, it doesn’t eliminate gluten. The fragments that remain are still large enough to provoke an immune reaction in sensitive individuals.
The result is that a conventional beer brewed from barley carries a meaningful gluten load from grain to glass. Ales and wheat-containing beers tend to have higher gluten levels than lagers. In one large analysis, conventional lagers averaged about 148 mg/kg of gluten, while ales and wheat beers ran significantly higher.
How Much Gluten Is in Different Beer Styles
Gluten levels vary widely depending on the grains used and the style of beer. The international standard for labeling a product “gluten-free” is below 20 mg/kg (20 parts per million). Most conventional beers exceed that threshold by a wide margin.
- Wheat beers: Around 6,000 mg/kg, by far the highest of any beer style. These use wheat as a primary grain alongside barley.
- Ales (including IPAs and stouts): Generally higher than lagers due to brewing methods and grain bills, though the range varies.
- Lagers: Tend to be on the lower end for conventional beers, averaging around 148 mg/kg in one study, but still well above the 20 ppm gluten-free cutoff.
Even within these categories, individual beers can vary enormously depending on the recipe, how much adjunct grain is used, and filtration methods. The takeaway: no conventional beer made from barley or wheat is safe for someone who needs to avoid gluten.
“Gluten-Removed” Beer Is Not Gluten-Free
Some breweries use enzymes to break down gluten proteins in beer that was brewed from barley. These products are often marketed as “gluten-removed” or “crafted to remove gluten.” The enzyme used, a prolyl endopeptidase, chops gluten into smaller peptide fragments. The idea is that smaller fragments won’t trigger an immune response.
The problem is that current testing methods can’t reliably verify how much gluten remains in these products. Standard antibody-based tests were designed to detect intact gluten proteins, not the fragments left after enzymatic treatment. Some fragments may still be large enough to cause harm but small enough to evade detection. Others might register on tests despite being too small to be biologically relevant. The science simply can’t distinguish between the two with confidence.
This is why U.S. regulators treat these products differently from truly gluten-free beer. The Alcohol and Tobacco Tax and Trade Bureau (TTB) does not allow barley-based beers treated with enzymes to carry a “gluten-free” label. Instead, they must say something like: “Product fermented from grains containing gluten and processed to remove gluten. The gluten content of this product cannot be verified, and this product may contain gluten.” That required disclaimer tells you everything you need to know about the level of certainty involved.
What Makes a Beer Truly Gluten-Free
The only way to make beer that’s genuinely gluten-free is to brew it from grains that never contained gluten in the first place. The most common alternatives are sorghum, millet, rice, buckwheat, and corn. These grains lack the specific storage proteins that define gluten, so the finished beer tests clean.
A typical gluten-free brew might use 40 to 70 percent sorghum malt as the base, with the remainder coming from a blend of millet, rice, buckwheat, or corn. These beers have improved considerably in recent years, though they tend to taste different from barley-based beer because the grains contribute different flavors and body.
Under FDA regulations, a product labeled “gluten-free” (or “no gluten,” “free of gluten,” or “without gluten”) must contain less than 20 ppm of gluten. Beers brewed entirely from gluten-free grains generally clear this threshold easily. However, even among beers labeled gluten-free, testing isn’t perfect. One study found that 3 out of 41 gluten-free labeled beers exceeded 30 mg/kg when tested with a competitive antibody assay, suggesting that cross-contamination or ingredient issues can occasionally occur.
Why the 20 ppm Threshold Matters
The 20 ppm standard isn’t arbitrary. It’s based on research into the lowest level of gluten that reliably triggers symptoms and intestinal damage in people with celiac disease. At that threshold, most people with celiac can consume the product without measurable harm, though individual sensitivity varies.
For someone with celiac disease or non-celiac gluten sensitivity, the practical guidance is straightforward. Conventional beer is off the table regardless of style. Gluten-removed beer carries unverifiable risk. Beer brewed from naturally gluten-free grains is the safest option, and checking the label for the specific “gluten-free” claim (rather than “crafted to remove gluten”) is the most reliable way to tell the difference at the store.