How we check gluten

Every verdict on this site is computed by code from facts we can point to: a quote from the maker, a USDA ingredient record or a GFCO listing, each with its link and the date we checked it. Nothing is written in by hand and nothing is guessed.

How a product verdict is computed

We read the verified facts for the product's flavour of record, in this order:

Claims first. A gluten-free statement from the maker, or a listing on the GFCO certified product list, gives Labeled gluten-free. A maker statement that the product contains gluten gives Contains gluten. Claims override the ingredient list. A gluten-free claim and a contains-gluten claim together give Not verified.
Then the ingredients. We check each ingredient list (USDA FoodData Central or the maker's own) and the maker's "Contains:" line for wheat, barley, rye, malt, brewer's yeast and related terms. Any of them gives "Contains gluten". Oats that are not labeled gluten-free give "Not verified". A list with neither gives No gluten ingredients, not labeled.
Nothing to check gives "Not verified". We say so rather than guess.

A USDA ingredient record can only show that a product contains gluten or that no gluten ingredient is listed. It never shows that a product is gluten-free; only a maker statement or a certification can.

Food guides

A food page (quinoa, soy sauce, barley) shows what public health and celiac organizations say about that food, in their own words: the FDA, NIDDK at the National Institutes of Health, the Celiac Disease Foundation, the Gluten Intolerance Group, the National Celiac Association and Beyond Celiac. The status (naturally gluten-free, contains gluten, or depends on the product) is what the cited statements say. If they give different answers, the page says "Sources disagree", shows both sides in their own words and explains the difference. Each food page also has a short explanation in our words, and every part of it links to the sources on the page that support it. When a source names a broader term (for example "wheat" for farro), the page marks it and shows the exact words.

When a page is shown to search engines

Every page is live, but only pages that meet these bars are offered for indexing. The others carry a noindex tag until the data is there.

Labeled gluten-free: at least one maker statement or one GFCO listing.
Contains gluten: at least one source that states its date, shown with the ingredient quote.
No gluten ingredients listed, not labeled gluten-free: at least 2 independent sources of different types. Two USDA records count as one.
Not verified: never.
Every product page also needs at least 5 sourced facts in its Gluten Facts panel, and either a flavour table with at least 2 flavours or at least 2 other products from the same brand with a verdict. Two product pages that read almost the same (80% or more) are not both indexed.
Food guides: a status backed by at least 2 different publishers, at least 3 GFCO-certified alternatives when the food contains gluten or depends on the product, and at least 150 words of explanation written for that food from its cited sources. When sources disagree, the two sides must come from at least 2 different publishers.
Brand pages: at least 100 words and 2 indexed products. Lists: an introduction of at least 100 words and at least 5 indexed products.

Dates on every page

Last checked: The latest date we verified a fact on the page against its source.
Source date: The date the source itself states: the USDA publication date, or the date printed on the maker's page. "Not stated" means the page carries no date.
Fetched: When we loaded the source page. We keep a fingerprint (SHA-256) of what we loaded, so a later change can be detected.

Recipes change. The package label always wins over this page. This site is general information, not medical advice; if you have celiac disease, follow your doctor's guidance.

Found something out of date? Tell us with the page and, if you can, the source.