Wheated bourbon is generally considered gluten free despite being made with wheat. The distillation process removes gluten proteins, and lab testing of wheated bourbons like Maker’s Mark has found gluten levels below 5 parts per million, well under the 20 ppm threshold used to define “gluten free.”
What Makes Bourbon “Wheated”
All bourbon must contain at least 51% corn in its grain recipe, known as the mash bill. In most bourbons, rye fills out the remaining grain alongside malted barley. Wheated bourbons swap the rye for wheat, which typically makes up 15% to 25% of the mash bill. The result is a softer, smoother flavor profile. Popular wheated bourbons include Maker’s Mark, the Weller line, Larceny, Old Fitzgerald, Rebel Yell, and the highly sought-after Pappy Van Winkle family.
So yes, wheat is a core ingredient. That raises an obvious concern if you have celiac disease or a gluten sensitivity.
Why Distillation Removes Gluten
Gluten is a protein. Distillation works by heating a liquid into vapor and then condensing it back into liquid. Proteins are too heavy to travel in that vapor, so they stay behind in the still. What comes out the other side is essentially free of protein, and therefore free of gluten.
This isn’t just theory. The FDA has confirmed that distillation removes all protein, including gluten, when good manufacturing practices are followed. Based on this science, the Alcohol and Tobacco Tax and Trade Bureau (TTB) issued a 2020 ruling that spirits distilled from gluten-containing grains can legally carry a “gluten-free” label, provided the distiller takes steps to prevent gluten from being reintroduced after distillation.
What Lab Testing Shows
Gluten Free Watchdog, an independent testing organization, has tested bourbon made from wheat-heavy mash bills. Maker’s Mark, which is made with soft red winter wheat, tested below 5 ppm gluten using one method and below 10 ppm using a second, more sensitive method designed to catch fragmented gluten proteins. Both results fall comfortably under the 20 ppm standard that the FDA uses for “gluten free” food labeling.
For context, 5 ppm means five milligrams of gluten per kilogram of product. At that level, you’d need to consume an enormous quantity before approaching a meaningful gluten exposure.
Barrel Sealing and Cross-Contamination
One lesser-known concern involves the barrels. It’s standard practice in cooperage to seal barrel heads with a wheat flour paste. Since bourbon ages in charred new oak barrels for years, some people worry that gluten could leach from that paste into the spirit.
Testing suggests this isn’t a real risk. Gluten Free Watchdog tested wine aged in oak barrels sealed with wheat paste and found all samples below 5 ppm using standard testing and below 10 ppm using the competitive method. The wheat paste isn’t fermented or broken down in a way that would hide gluten from testing, so these results are considered reliable. Bourbon aged in similar barrels would face the same negligible exposure.
The One Risk Worth Watching
Straight, unflavored wheated bourbon is not a meaningful source of gluten. The real risk comes from flavored or specialty bourbons that add ingredients after distillation. Honey, spices, caramel flavorings, or other additives introduced post-distillation haven’t gone through the same protein-stripping process. These additions could potentially contain gluten, and they wouldn’t necessarily be obvious from the label.
If you’re sticking to a traditional wheated bourbon like Maker’s Mark, Weller Special Reserve, Larceny, or Old Fitzgerald, you’re drinking a product that’s been through distillation with nothing gluten-containing added back in. If you’re reaching for a flavored bourbon or a limited-edition bottle with unusual finishing techniques, it’s worth checking what was added after distillation.
Celiac Disease vs. Wheat Allergy
Celiac disease is triggered specifically by gluten proteins. Since distillation removes those proteins, properly distilled wheated bourbon is considered safe for people with celiac disease by major organizations including the Celiac Disease Foundation.
A wheat allergy, on the other hand, can involve immune reactions to several different wheat proteins beyond gluten. The good news is that distillation removes all proteins, not just gluten. However, wheat allergy reactions can sometimes be triggered by trace amounts that fall below the detection limits of current testing. If you have a severe wheat allergy and haven’t tried distilled wheat-based spirits before, your experience may vary in ways that lab tests can’t fully predict.
Some people with celiac disease or gluten sensitivity also report reacting to distilled grain spirits despite the science suggesting they shouldn’t. Whether this is due to trace contamination, other compounds in the spirit, or the effects of alcohol itself on an already-sensitive gut is not fully understood. If you consistently feel worse after drinking bourbon but tolerate other spirits, that’s worth paying attention to regardless of what the lab results say.