Hidden gluten on food labels: what to look for in the US

Reading food labels is a fundamental skill for managing a safe gluten-free diet. At first, the lists of ingredients and different warnings can seem confusing. With a clear understanding of the rules and some practice, checking labels becomes a quick and routine part of gluten-free grocery shopping.

In the United States, food labeling is governed by specific regulations for both “gluten-free” claims and major allergens like wheat. However, these rules have limitations. Knowing what to look for beyond the most obvious terms is key to identifying products that are truly safe for your needs. This guide explains how to read US food labels to find hidden sources of gluten.

Understanding the “gluten-free” label

The most straightforward signal on a food package is a “gluten-free” claim. In the US, the Food and Drug Administration (FDA) has a specific rule for this term. For a manufacturer to label a food as “gluten-free,” “no gluten,” “free of gluten,” or “without gluten,” the food must contain less than 20 parts per million (ppm) of gluten.

This is a voluntary label. Companies are not required to put it on their products, even if the food is naturally gluten-free, like plain fruits and vegetables. Many companies choose to use the label on processed foods as a clear indicator for consumers. When you see this claim on a package, it is generally considered safe for people with celiac disease.

Some companies also use third-party certification symbols to show their products have been reviewed by an outside organization. These certifications also require products to meet the less than 20 ppm standard, and sometimes an even stricter one. These offer an additional layer of assurance for many people.

The wheat allergen label: what it covers and what it misses

Many people new to the gluten-free diet look for wheat on the label. US regulations require that major food allergens be clearly identified, and wheat is one of them. You will typically see this in one of two ways:

• In the ingredients list, the word “wheat” will be in parentheses after the ingredient. For example: “enriched flour (wheat flour, niacin…).”
• In a separate “Contains” statement near the ingredients list. For example: “Contains: Wheat, Milk, Soy.”

This is very helpful, but it has a significant limitation: the allergen law is for wheat, not gluten. Gluten is also found in barley and rye, which are not considered major allergens and do not require this special labeling. A product can be completely free of wheat ingredients but still contain gluten from barley or rye. This is why the phrase “wheat-free” does not automatically mean “gluten-free.” You must always check the full ingredients list for other gluten sources.

Ingredients that always contain gluten

When you scan an ingredients list, some words are clear red flags. If you see any of the following, the product is not gluten-free.

• Wheat (including all varieties like durum, semolina, spelt, farro, einkorn, and kamut)
• Rye
• Barley
• Malt (this is almost always made from barley. If from another source like corn, it must be specified, e.g., “corn malt”)
• Brewer’s yeast (this is a byproduct of beer brewing, which uses barley or wheat)
• Wheat starch (unless it has been processed to meet the under 20 ppm standard and the product is labeled “gluten-free”)

Ingredients to investigate further

Some ingredients can be tricky because they may or may not contain gluten depending on their source. For these items, you should look for a “gluten-free” label on the package. If there is no such label, it is safest to avoid the product or contact the manufacturer for more information.

1. Oats: Oats are naturally gluten-free, but they are very often grown and processed with the same equipment as wheat, leading to significant cross-contact. Always choose oats and oat-based products that are specifically labeled “gluten-free.” For more details, you can read more about whether oats are truly gluten-free. A small number of people with celiac disease may also have a separate reaction to the protein in oats, so it is wise to discuss this with your care team.
2. Starches: Food starch or modified food starch in the US must state if it comes from wheat, per allergen rules. If it just says “food starch” or “corn starch,” it is generally safe.
3. Natural and artificial flavors: In the US, flavorings rarely contain gluten. If a flavor contains wheat, it must be declared. However, barley is a very rare exception. Some “smoke flavor” can be derived from barley. If a product with vague “natural flavors” is not labeled gluten-free, caution is warranted.
4. Dextrins and maltodextrin: In the US, these are typically derived from corn, potato, or rice. If derived from wheat, it would have to be labeled as such.
5. Yeast: While brewer’s yeast contains gluten, other types like nutritional yeast or active dry yeast for baking are typically gluten-free. Check the package to be sure.

Labels the FDA rules do not cover

The FDA gluten-free rule and the wheat allergen rule apply to foods the FDA regulates. Many meat, poultry and some egg products are regulated by the USDA instead, where allergen labeling works differently, and most alcoholic drinks fall under yet another agency. For sausages, deli meats, marinated meats and drinks, read the full ingredient list carefully and contact the maker when in doubt.

Statements such as “may contain wheat” or “made in a facility that also processes wheat” are voluntary in the US and are not standardized. Their absence does not prove a product is free of cross-contact, and their presence does not tell you how much gluten, if any, is in the food. If you are eating out, it is important to know which questions to ask a restaurant about gluten.

Putting it all together: A label-reading strategy

With this information, you can develop a consistent routine for checking any packaged food.

First, look for a prominent “gluten-free” label. This is the fastest way to confirm a product is safe. If you find one, the product meets the FDA standard of less than 20 ppm, though you still choose what level of caution is right for you with your care team.

If there is no gluten-free claim, your next step is to read the “Contains” statement. If you see “Contains: Wheat,” the product is not safe.

If there is no gluten-free claim and no wheat in the “Contains” statement, you must read the entire ingredients list carefully. This is the final and most important step. Look for any sources of barley or rye. Pay close attention to terms like malt, malt syrup, malt extract, malt vinegar, and brewer’s yeast. Also check for rye. If you find any of these, the product contains gluten and is not safe.

This systematic approach helps ensure you do not accidentally consume gluten from an unlabeled source. Over time, you will become familiar with which brands and products are reliable, making the process much faster.

When to loop in your doctor or dietitian

Properly managing celiac disease or another gluten-related disorder goes beyond reading labels. It is a good idea to consult with a healthcare professional in certain situations:

• If you suspect you have celiac disease but have not been diagnosed, talk to a doctor before starting a gluten-free diet. Testing is most accurate while you are still consuming gluten.
• After a new diagnosis, a registered dietitian with experience in celiac disease can help you build a balanced, nutritious diet and avoid common pitfalls.
• If you continue to experience symptoms despite following a strict gluten-free diet, your doctor can investigate other potential causes.