Contents
Last reviewed: 2026-07-20
The Short Answer
In the US, a food labeled "gluten-free" is a legal claim: the product must contain less than 20 parts per million (ppm) of gluten, including from cross-contact during manufacturing. If a product carries that label, you do not need to scan the ingredient list for hidden wheat, barley, or rye.
If a product is not labeled gluten-free, the ingredient list is your only source of information — and a few ingredient names are worth knowing on sight.
What "Gluten-Free" Legally Means
The FDA's gluten-free labeling rule applies to any food that uses the words "gluten-free," "no gluten," "free of gluten," or "without gluten." To use any of those claims, a manufacturer must ensure the food contains less than 20 ppm of gluten — a threshold that accounts for unavoidable trace amounts, including gluten introduced by shared equipment or packaging.
A gluten-free label can still list wheat-derived ingredients, as long as they were processed to remove gluten and the finished product tests under 20 ppm. Gluten-free wheat starch is the main example — it is legal in a gluten-free product, and if it's present, the label must carry a disclaimer: "The wheat has been processed to allow this food to meet the Food and Drug Administration requirements for gluten-free foods."
Two phrases that sound similar but are not regulated the same way:
- "Made with no gluten-containing ingredients" — a voluntary claim. It does not have to meet the 20 ppm standard unless the product is also labeled gluten-free.
- Allergen advisory statements like "processed in a facility that also processes wheat" — voluntary manufacturing disclosures, not a measurement of what's actually in the food. A product can carry this statement and still be genuinely gluten-free, or omit it and still contain gluten. Studies checking these statements against lab-tested gluten content have found them to be a weak predictor either way.
Third-party certification (GFCO is the most common in the US) adds independent lab testing on top of the manufacturer's own claim. It is not legally required, but it is a stronger guarantee than the label alone.
When There Is No Gluten-Free Label
Without that label, the ingredient list is what you have. Start with the obvious: wheat, barley, rye, and anything derived from them — including spelt, kamut, triticale, farina, semolina, and malt in any form (malt extract, malt syrup, malt flavoring, malt vinegar, barley malt).
Beyond the obvious grains, a handful of ingredient names are worth double-checking specifically:
- Modified food starch — usually corn in the US, but can be wheat-derived.
- Dextrin — same as above.
- Hydrolyzed vegetable protein / hydrolyzed protein — can be wheat-based.
- Natural flavoring and yeast extract — occasionally carry a gluten source; manufacturers are not required to break down what's inside a "flavoring."
- Soy sauce — traditionally brewed with wheat. Tamari is often, but not always, wheat-free — check the label either way.
One thing worth knowing so you're not avoiding food unnecessarily: under US labeling law (FALCPA), if any of these catch-all ingredients — modified food starch, dextrin, maltodextrin, glucose syrup, caramel color, natural or artificial flavoring — actually contains wheat protein, the word "wheat" is legally required to appear in the ingredient list or in a "Contains" statement. If "wheat" doesn't appear anywhere on the label, that ingredient does not contain wheat protein, by law. A few ingredients that sound suspicious but are reliably gluten-free regardless of their starting material:
- Caramel color and caramel flavoring — made from corn in the US.
- Maltodextrin and maltose — made from corn in the US.
- Dextrose and glucose syrup — considered gluten-free even when the starting grain is wheat, because the processing removes gluten.
- Distilled vinegar — gluten-free even if distilled from a wheat source; distillation leaves the gluten protein behind.
Wheat Is an Allergen. Barley and Rye Are Not.
This is one of the more consequential gaps in US labeling law. Wheat is one of the nine major food allergens under federal law, so if a packaged food contains wheat protein, "wheat" must appear on the label — either in the ingredient list or in a separate "Contains" statement.
Barley and rye are not covered by that requirement. A product can contain barley or rye — most commonly as malt — without any legal obligation to flag it the way wheat is flagged. This is exactly why malt in its various forms deserves a second look: it will not show up in a "Contains" statement, only in the ingredient list itself, often under a name that doesn't obviously say "barley."
Oats Need Their Own Check
Oats are naturally gluten-free, but most oats sold in the US are cross-contaminated with wheat, barley, or rye during farming and processing. Regular oats and oat products are not safe for celiac disease unless specifically labeled gluten-free. This applies to oat flour, oat milk, and granola as much as to a bag of rolled oats. For more on why, see What Is Gluten?.
Restaurant and Deli Labels Work Differently
Everything above applies to packaged food regulated by the FDA. Restaurant menus are not required to follow the same labeling rule, and a "gluten-free" item on a menu is not a legal claim in the same sense a packaged product's label is. Deli counters, bakeries, and restaurants can use the term more loosely, and cross-contact in a shared kitchen is a separate risk that a menu label does not address. Ask how the dish is prepared, not just whether it's marked gluten-free.
When You're Not Sure
If an ingredient's source isn't clear from the label and the product isn't certified gluten-free, the manufacturer's contact information is usually on the package. Calling to ask about a specific ingredient is a normal and common thing to do — companies that sell to people with celiac disease field these calls regularly.
Related Articles
Sources
- U.S. Food and Drug Administration. Questions and Answers on the Gluten-Free Food Labeling Final Rule. https://www.fda.gov/food/nutrition-food-labeling-and-critical-foods/questions-and-answers-gluten-free-food-labeling-final-rule — accessed 20 July 2026
- Celiac Disease Foundation. Gluten-Free 101: What You Need to Know. https://celiac.org/2016/01/31/gluten-free-101-need-know/ — accessed 20 July 2026
- Celiac Disease Foundation. Label Reading & the FDA. https://celiac.org/gluten-free-living/gluten-free-foods/label-reading-the-fda/ — accessed 20 July 2026
- Beyond Celiac. The FDA's Ruling on Gluten-Free Food Labeling. https://www.beyondceliac.org/gluten-free-diet/food-labeling-laws/ — accessed 20 July 2026
- Gluten Free Watchdog. Allergen advisory statements for wheat do NOT appear to be useful predictors of quantifiable gluten. https://www.glutenfreewatchdog.org/news/allergen-advisory-statements-for-wheat-do-not-appear-to-be-useful-predictors-of-the-potential-for-quantifiable-gluten-in-database-reviews/ — accessed 20 July 2026