The most reliable way to know if something is gluten free is to check for an FDA-compliant “gluten-free” label, which means the product contains less than 20 parts per million (ppm) of gluten. But labels only tell part of the story. Many foods are naturally gluten free, some ingredients hide gluten under unfamiliar names, and certain products like alcohol and medications follow different rules entirely. Here’s how to navigate all of it.
What the “Gluten-Free” Label Actually Guarantees
Since 2014, the FDA has required that any food labeled “gluten-free,” “no gluten,” “free of gluten,” or “without gluten” must contain less than 20 ppm of gluten. That threshold is the lowest level that can be reliably detected using validated testing methods, and it’s the same standard used internationally. Most people with celiac disease can tolerate foods at or below this level without triggering symptoms or intestinal damage.
To qualify for the label, a food also cannot contain any ingredient that is wheat, rye, barley, or a crossbreed of these grains, unless that ingredient has been processed to bring gluten below 20 ppm. Wheat starch is one example: it can appear in a gluten-free product, but the label must include a note explaining that the wheat was processed to meet FDA gluten-free standards. If you see both “gluten-free” and “Contains wheat” on the same package, look for that asterisk or clarifying statement.
The label is voluntary. Manufacturers aren’t required to use it, so plenty of safe foods won’t carry it. But when they do use it, they’re legally bound to meet the standard.
Third-Party Certifications Go Further
Some products carry a certification seal from an independent organization that audits the manufacturer’s testing and production processes. These certifications vary in strictness:
- Gluten-Free Certification Program (GFCP): Endorsed by Beyond Celiac and the Canadian Celiac Association. Products must contain less than 20 ppm of gluten, matching the FDA standard.
- Gluten-Free Certification Organization (GFCO): Endorsed by the Gluten Intolerance Group. Products must test below 10 ppm, half the FDA threshold.
- Gluten Free Food Program (GFFP): Endorsed by the National Celiac Association and other global organizations. Products must contain less than 5 ppm.
If you’re highly sensitive, choosing products with the GFCO or GFFP seal gives you an extra margin of safety beyond what the FDA requires.
Foods That Are Naturally Gluten Free
Many whole foods never contain gluten to begin with. Fresh fruits, vegetables, plain meats, fish, poultry, eggs, beans, seeds, nuts, and legumes are all naturally gluten free in their unprocessed forms. Rice, corn, quinoa, millet, and potatoes are safe starches.
The trouble starts with processing. Dried, frozen, or canned versions of these foods may include sauces, seasonings, or coatings that contain gluten. A plain chicken breast is gluten free. A pre-seasoned, frozen chicken breast might not be. The same applies to canned soups with vegetables, flavored nuts, or frozen vegetables in a sauce. Always check the ingredient list on anything that isn’t completely unprocessed.
Ingredient Names That Hide Gluten
Gluten doesn’t always appear on a label as “wheat” or “barley.” Several common ingredients can contain gluten under names you might not recognize. These are the ones to watch for:
Malt in any form, including malt flavoring, malt extract, and malt syrup, is almost always made from barley. Any product listing malt is not gluten free. Malt vinegar falls into the same category and should be avoided, though other vinegars (white, apple cider, balsamic) are generally safe.
Brewer’s yeast is a byproduct of beer production and carries gluten from the malt and grains used in brewing. It’s different from baker’s yeast or nutritional yeast, which are typically safe. Yeast extract and autolyzed yeast extract can also be made from spent brewer’s yeast and may contain trace gluten.
Natural flavors and seasonings are broad categories that sometimes include wheat flour, wheat starch, or barley malt flour as carrier agents. If a product isn’t labeled gluten free, barley-derived ingredients in natural flavors don’t have to be disclosed on the label. That’s a gap in allergen labeling law, since only wheat (not barley or rye) is one of the major allergens required to be declared. Contacting the manufacturer is sometimes the only way to confirm safety.
A few other ingredients sit in a gray zone. Modified food starch and dextrin may be derived from wheat, though in the U.S. they’re usually made from corn. If wheat is the source, it must be declared on the label. Caramel coloring can technically be made from malt syrup or wheat starch, though this is rare in the U.S. Rice syrup sometimes uses barley enzymes to break down the rice starch, and recent testing suggests those enzymes may carry enough barley protein to cause problems for people with celiac disease. Smoke flavoring in dry form occasionally uses barley malt flour as a base.
The Oat Problem
Oats are naturally gluten free, but they’re one of the most commonly contaminated grains because they’re often grown near wheat fields and processed on shared equipment. A bag of conventional oats frequently tests above the 20 ppm threshold.
Look for oats specifically labeled gluten free. Within that category, there’s an important distinction. “Purity protocol” oats are grown, harvested, transported, and processed entirely separate from gluten-containing grains throughout the supply chain. Mechanically or optically sorted oats, by contrast, are conventional oats that have been run through equipment to remove stray wheat, barley, or rye kernels based on size, shape, or color. According to GFCO guidelines, sorting equipment should not be used as a substitute for the purity protocol, only as a supplement to it. If you have celiac disease, purity protocol oats are the safer choice.
Alcohol Has Its Own Rules
Alcoholic beverages are regulated by the Alcohol and Tobacco Tax and Trade Bureau (TTB), not the FDA, but the gluten-free standard is the same: under 20 ppm. Spirits distilled from non-gluten grains (vodka from potatoes, rum from sugarcane, tequila from agave) can be labeled gluten free. Wine and hard cider made without gluten-containing ingredients can also carry the claim.
The complicated category is alcohol made from wheat, barley, or rye. Distillation removes most gluten proteins, but the TTB does not allow these products to simply say “gluten-free.” Instead, they can state that the product was “distilled from grains containing gluten, which removed some or all of the gluten,” followed by a required disclaimer: “The gluten content of this product cannot be verified, and this product may contain gluten.”
Beer is the highest-risk alcoholic beverage. Traditional beer is fermented from barley or wheat and is not distilled, so it retains gluten. Some beers are marketed as “crafted to remove gluten,” meaning they’ve been treated with enzymes to break down gluten proteins, but they must carry the same disclaimer about unverifiable gluten content. Truly gluten-free beers are brewed from sorghum, rice, millet, or other safe grains and will be labeled accordingly.
Medications and Supplements
Unlike food, there is no mandatory gluten-free labeling standard for medications. The FDA has issued draft guidance recommending that drug manufacturers include the statement “Contains no ingredient made from a gluten-containing grain” when that’s accurate, but it’s not yet required. For over-the-counter drugs, check the “inactive ingredients” section on the Drug Facts panel. For prescription medications, ingredients are listed in the “Description” section of the labeling. If you don’t see wheat gluten or wheat flour listed, the product is unlikely to contain gluten at a level that would harm someone with celiac disease. When in doubt, a pharmacist can check the inactive ingredient database or contact the manufacturer directly.
Cross-Contact at Home and in Restaurants
A food can start gluten free and pick up gluten from shared surfaces, utensils, or cooking oil. At home, this means using separate cutting boards and cooking equipment for gluten-free foods, and keeping storage areas clean of flour dust and crumbs. Wheat flour can stay airborne for hours after use, settling on nearby surfaces and uncovered foods.
Restaurants present a bigger challenge because you can’t control the kitchen. Research on shared food preparation environments has found that even trained kitchen staff can inadvertently contaminate gluten-free dishes. One study of pizza restaurants found that wheat flour residue becomes aerosolized during handling, contaminating gluten-free pizzas and raw materials throughout the kitchen. The researchers recommended that restaurants use gluten-free flour for all rolling and dusting, not just for gluten-free orders. French fries are another common risk: if they’re cooked in the same fryer as breaded items, they pick up gluten from the shared oil.
When eating out, ask whether gluten-free items are prepared with separate equipment, cooked in dedicated fryers, and handled with clean utensils. A restaurant that has thought through these details is far more likely to deliver a genuinely safe meal than one that simply offers a “gluten-free menu” without clear kitchen protocols. Advisory statements like “may contain wheat” or “processed in a facility that also processes wheat” are voluntary and not standardized, so their absence doesn’t guarantee safety, and their presence doesn’t tell you how much risk actually exists.