This page is about celiac disease - spelled coeliac disease in the UK and Ireland. It is the same condition, and both spellings appear in the sources below.
Kort opsummeret
- It is a voluntary statement not regulated, and not a measurement.
- The amount is unknown unlike "gluten-free", which is a tested ceiling.
- The warning was designed with allergy in mind wheat allergy, not celiac disease.
- Testing goes both ways products with and without the warning can exceed 20 ppm.
- Coeliac UK advises avoiding them we say so because we don't agree with everyone, and you should know where the disagreement is.
- You decide we give you the whole picture.
Two labels that look similar - and are nothing alike
| "Gluten-free" | "May contain traces of gluten" | |
|---|---|---|
| Regulated? | Yes | No - entirely voluntary |
| Threshold? | Yes, below 20 ppm | None |
| Tested? | Yes | No - it is a risk assessment, not a measurement |
| Consistent across brands? | Yes | No - unharmonized |
| Can you steer by it? | Yes | No |
Why it can't be used as a decision tool
- It is the manufacturer's own judgment, not a measurement. The wording is added to cover a theoretical risk of cross-contact somewhere in production. There is not necessarily any analysis behind it.
- There is no limit. "Traces" is undefined. In practice it can cover anything from zero to an amount that matters - and you cannot tell the difference.
- It is not applied consistently. Two nearly identical products can be labeled differently, simply because the two manufacturers assessed the risk differently.
- Most importantly: the absence of the warning is not a guarantee. If a package does not say "may contain traces of gluten", that does not mean it was tested and found gluten-free. It only means the manufacturer chose not to print it. This is where the label is most often misread.
No warning is not a safety stamp
The most common misreading is treating the absence of "may contain traces" as confirmation that a food is safe. It isn't. The statement is voluntary - a manufacturer can leave it off without having tested anything.
It has been measured: the label does not predict gluten content
This is not a theoretical point. Researchers have measured gluten in products with and without precautionary allergen labelling (PAL) and compared the two groups.
In a study of products with no gluten-containing ingredients, gluten was found at 5 mg/kg or more in 20 of 77 products WITH the warning - and in 10 of 51 products WITHOUT it. At the threshold that matters legally (20 mg/kg = 20 ppm), the picture was essentially identical: 3 of 77 with the warning and 3 of 51 without.
In other words, the warning said nothing useful about what was actually in the product - in either direction. A review by Gluten Free Watchdog reached the same conclusion.
That is exactly why the label fails as a decision tool: it is equally unreliable whether it is there or not.
Who is the statement really for?
Precautionary allergen labelling was developed mainly with allergy in mind - wheat allergy, for instance - where even very small amounts can trigger a fast, allergic reaction. Celiac disease works differently: here it is repeated exposure over time that damages the small intestine.
What does that mean if you have celiac disease? (this is where organizations disagree)
Here we have to be honest: the major celiac organizations do not fully agree, and we say that out loud rather than picking the answer that sounds tidiest.
- Coeliac UK advises avoiding products with "may contain" labeling unless the manufacturer has specifically confirmed the product is suitable for a gluten-free diet. Their reasoning: the manufacturer has judged that there is an unavoidable risk of cross-contact.
- The measurements above point the other way: avoiding exactly those products creates false reassurance, because products without the warning were over the limit just as often. You don't remove the risk - you just narrow your diet.
How to hold both of those at once
What you can actually steer by
- The "gluten-free" label (regulated, tested, below 20 ppm) and foods that are naturally gluten-free. If a product carries both "gluten-free" and "may contain traces", the "gluten-free" claim is the documented one.
- If you are at the highly sensitive end, there is nothing wrong with leaving "may contain" products out for your own peace of mind - but know that it is not a guarantee, and that it does not replace looking for the "gluten-free" label.
- If you are unsure about a specific product, the only real answer is to ask the manufacturer. That is also Coeliac UK's advice.
One thing not to do
Don't use the warning as an argument about what other people are allowed to eat. That is precisely the misreading that spreads: that no warning means "safe" and a warning means "dangerous". Neither follows from the label.
This may change
EU harmonization is on the way
The EU is working to harmonize precautionary allergen labelling, and common rules are expected in the coming years (current indications point to around 2027). If that happens, "may contain traces of gluten" could gain a real, defined meaning. Until then, everything above applies.
Frequently asked questions
Can I eat something labeled "may contain traces of gluten"?
The label doesn't tell you whether the food is safe - it is voluntary and has no legal threshold. Coeliac UK advises avoiding these products unless the manufacturer has confirmed they are suitable. Testing, however, shows that products without the warning contain gluten just as often. What you can steer by is the "gluten-free" label.
How much gluten is a "trace"?
Nobody knows. The wording has no defined limit and is not necessarily based on a measurement.
Is a product without the warning safe?
Not necessarily. In one study, 3 of 51 products without any warning contained more than 20 ppm gluten - essentially the same share as among products carrying the warning (3 of 77). The absence of the warning only means the manufacturer chose not to print it.
So what should I go by?
The "gluten-free" label (regulated, tested, below 20 ppm) and foods that are naturally gluten-free. When you are unsure about a specific product, ask the manufacturer.