What "Gluten-Free" Means on a US Food Label

In the US, a food labeled "gluten-free" must contain less than 20 parts per million of gluten, which is less than 20 milligrams per kilogram of food. The claim is voluntary and is defined in 21 CFR 101.91.

1. Why the definition matters

The FDA estimates that about 3 million people in the United States have celiac disease. It explains that in people with celiac disease, foods containing gluten trigger antibodies that attack and damage the lining of the small intestine, which limits nutrient absorption and raises the risk of other serious health problems. The FDA says its definition helps consumers, especially those with celiac disease, be confident that "gluten-free" foods meet a defined standard.

The claim is voluntary. A manufacturer does not have to use it, but if it does, the food must meet every requirement.

2. Which grains contain gluten

The regulation defines a "gluten-containing grain" as any of these, or their crossbred hybrids:

• wheat, including any species of the genus Triticum
• rye, genus Secale
• barley, genus Hordeum

It gives triticale, a cross between wheat and rye, as an example of a hybrid, and spelt wheat as an example of a gluten-containing grain ingredient. "Gluten" means the proteins naturally found in these grains that may cause harm in people with celiac disease.

3. The 20 ppm rule

A food labeled "gluten-free" must meet two conditions. First, it must either inherently not contain gluten, or it must not contain:

1. an ingredient that is a gluten-containing grain, such as spelt wheat
2. an ingredient derived from a gluten-containing grain that has not been processed to remove gluten, such as wheat flour
3. an ingredient derived from such a grain that has been processed to remove gluten, such as wheat starch, if using it results in 20 ppm or more gluten in the food

Second, any unavoidable presence of gluten must be below 20 parts per million. The regulation spells out what that means: below 20 milligrams of gluten per kilogram of food.

To put that in perspective with simple arithmetic: 20 mg per kilogram is 1 mg per 50 grams. So a 50-gram serving of a compliant food contains less than 1 milligram of gluten.

4. The same rule covers similar wording

The regulation applies the same requirements to "no gluten," "free of gluten," and "without gluten." A food using any of those phrases without meeting the definition is considered misbranded.

5. When "wheat" and "gluten-free" appear together

Point 3 above means a product can contain processed wheat starch and still be gluten-free if it stays under 20 ppm. Because that can look contradictory next to a "Contains wheat" allergen statement, the regulation requires a specific explanation. The word "wheat" in the ingredient list or "Contains" statement must be followed by an asterisk pointing to this sentence:

"The wheat has been processed to allow this food to meet the Food and Drug Administration (FDA) requirements for gluten-free foods."

If you see a gluten-free claim and the word wheat on the same package, look for that asterisk.

6. Fermented, hydrolyzed, and distilled foods

Testing for gluten does not work well for every food. In a final rule issued on August 12, 2020, the FDA set compliance requirements for fermented or hydrolyzed foods. The FDA lists examples: yogurt, sauerkraut, pickles, cheese, green olives, FDA-regulated beers and wines (generally those under 7 percent alcohol), and hydrolyzed plant proteins used in soups, sauces, and seasonings. The FDA says this rule did not change the definition of "gluten-free."

For these foods, the regulation requires manufacturers to keep records showing that:

• the food was gluten-free before fermentation or hydrolysis
• they evaluated their processing for the potential for gluten cross-contact
• where a risk was found, they put measures in place to prevent it

Those records must be kept for at least 2 years. For distilled foods, such as vinegar, the FDA verifies compliance by checking for the absence of protein in the distilled component.

7. One national standard

The regulation also states that a state or local government may not set a different definition or different requirements for "gluten-free" and the related claims. The same meaning applies across the country.

8. What the claim does not tell you

A "gluten-free" label tells you about gluten. It does not tell you about other allergens, and it is not a statement about calories, sugar, or overall nutrition. The Nutrition Facts panel and the ingredient list still matter.

9. Key takeaways

• "Gluten-free" is a voluntary FDA claim with a legal definition in 21 CFR 101.91, first set in 2013.
• Any unavoidable gluten must be below 20 parts per million, which is less than 1 mg in a 50-gram serving.
• Wheat, rye, barley, and their hybrids are the gluten-containing grains; processed wheat starch can qualify if the food stays under the limit.
• "No gluten," "free of gluten," and "without gluten" follow the same rules.
• Fermented and hydrolyzed foods carrying the claim require records showing they were gluten-free before processing.

This article explains how to read labels and is not medical advice. If you have celiac disease or another gluten-related condition, work with a doctor or registered dietitian on your diet.