Quick answer: Under FDA rules, a food labeled "gluten-free," "no gluten," "free of gluten," or "without gluten" must contain less than 20 parts per million (ppm) of gluten — the lowest level reliably detectable by validated testing. "Gluten-free" therefore does not mean zero; it means below a threshold most people with celiac disease tolerate. The food also cannot contain wheat, rye, barley, or their crossbreeds, or an ingredient from those grains that still leaves 20 ppm or more. Some third-party certifications use a stricter threshold than the FDA''s. The safest sources remove the guesswork entirely — a dedicated gluten-free kitchen has no gluten on site at all.
Most people assume "gluten-free" on a package is a marketing phrase. It is not. It is a legal claim with a specific number behind it, defined by the FDA in 21 CFR 101.91, effective in 2013 with compliance required in 2014.
Knowing that number — and its limits — is the difference between guessing and shopping with confidence.
The number: under 20 ppm
To carry a "gluten-free," "no gluten," "free of gluten," or "without gluten" claim, a food must contain less than 20 parts per million of gluten. That is 20 milligrams of gluten per kilogram of food — a very small amount.
Why 20 and not zero? Because 20 ppm is the lowest level that validated testing methods can reliably detect. There is no validated test for "zero" gluten, which means no honest label can promise zero. The FDA set the limit at the edge of what science can actually verify, and at a level most people with celiac disease tolerate.
The grain rules behind the claim
The ppm limit is not the whole rule. A food bearing a gluten-free claim also must not contain:
- Wheat, rye, barley, or their crossbreeds (such as triticale)
- An ingredient derived from those grains that has not been processed to remove gluten
- An ingredient processed to remove gluten that still leaves the food at 20 ppm or more
Wheat starch is the special case people ask about: it is permitted only if the finished food still tests under 20 ppm.
What the label does NOT tell you
- It does not mean zero gluten. It means below a measurable threshold.
- It does not certify the kitchen. The claim is about the product, not about whether the facility handles wheat elsewhere.
- "Wheat-free" is not "gluten-free." Rye and barley contain gluten too. A wheat-free product can absolutely glute you.
- Certification is a separate layer. Some third-party certification programs apply a stricter threshold than the FDA''s 20 ppm — check the specific program''s published standard.
Hidden gluten to scan for
- Malt — usually barley-derived: malt syrup, malt extract, malt vinegar, malted milk
- Brewer''s yeast
- Some soy sauces (traditional soy sauce is brewed with wheat)
- Thickeners, seasoning blends, and "natural flavors" worth a second look
- "Processed to remove gluten" claims — legal, but read the whole label
Read the ingredient list and any "contains wheat" allergen statement every time. Formulations change without warning, and the safe brand from last year is not automatically safe today.
The safest option removes the math
Reading labels is an essential skill, and you will get fast at it. But the safest meals are the ones where cross-contamination was never possible in the first place.
That is what a dedicated gluten-free facility is: no wheat, rye, or barley on site at all, so there is nothing to measure, nothing to trace, and nothing to worry about. SmashMeals has been 100% gluten-free since 2017.
"'Gluten-free' on a package means under 20 parts per million — not zero. In our kitchen there's no gluten to measure in the first place, which is a different kind of peace of mind." — Lew Kizer
See this week''s menu or read about our dedicated gluten-free kitchen.
Once you can read a label, the store stops being scary
Ten seconds per package, and you know. For everything else — the busy weeks, the travel days, the newly diagnosed weeks — trusted dedicated gluten-free sources fill the gap.
Learn more: FDA: Gluten and Food Labeling and the Celiac Disease Foundation.
Related reading: Just Diagnosed With Celiac? Your First 30 Days and Beyond the Gut: Anemia, Osteoporosis and Neuropathy.
"Whatever you do, do it from the heart, as something done for the Lord and not for people." — Colossians 3:23 (CSB)