The dangerous assumption at passport control
A British shopper becomes accustomed to a particular visual habit.
Pick up packet.
Find ingredients.
Scan the bold words.
That habit works because British food law requires particular allergens to be emphasised.
Travel abroad and it is very easy to carry the habit across the border while unknowingly leaving the law behind.
The package may look almost identical.
The ingredients may still be written in English.
The supermarket may even be part of a chain you recognise.
But allergen regulation is not globally identical.
For mustard allergy, this matters enormously.
Britain and the European Union: mustard has special status
UK food-information rules retain the familiar list of 14 regulated allergens, including mustard.
European Union food-information legislation likewise includes mustard among the substances or products causing allergies or intolerances for which specific declaration requirements apply.
So somebody travelling between Britain and EU countries is operating within broadly familiar territory as far as mustard's status as a regulated allergen is concerned.
There can still be differences in language, national implementation, restaurant practice and the particular foods being eaten.
But mustard itself has explicit legal recognition.
Cross the Atlantic and the picture changes.
In the United States, mustard isn't one of the "Big Nine"
US federal law identifies nine major food allergens:
milk, egg, fish, crustacean shellfish, tree nuts, peanuts, wheat, soybeans and sesame.
Mustard is not on that federal major-allergen list.
This does not mean American food manufacturers are free to secretly add mustard while providing no ingredients information at all. General US ingredient-labelling rules still apply to packaged foods.
What changes is mustard's special allergen status.
A British consumer accustomed to seeing MUSTARD specially emphasised should not assume that an American label will draw attention to it in the same way.
Nor should they assume that a US "Contains" allergen statement will mention mustard.
If a packet says:
CONTAINS: WHEAT, MILK, EGG
that does not mean:
"These are every possible allergen in the product."
It means those are the applicable major allergens being declared in that format.
For somebody with mustard allergy, the ordinary ingredients list remains particularly important.
This is a small legal difference with a very practical consequence.
Canada is different again
Canada specifically recognises mustard as a priority food allergen.
Canadian regulatory guidance requires priority allergens, gluten sources and added sulphites to be declared in prescribed ways on prepackaged foods, with mustard included among the priority allergens.
So a British traveller with mustard allergy may actually find Canada's regulatory treatment of mustard more familiar than that of the neighbouring United States.
This produces a wonderfully useful example of why the phrase:
"the major allergens"
should always make us ask:
Major allergens according to whom?
There is no single worldwide list.
Why countries have different lists
At first this can seem scientifically absurd.
Surely a food is allergenic whether it crosses a border or not?
Of course.
The biology doesn't change at customs.
The regulatory prioritisation does.
Countries and regions construct mandatory allergen lists using evidence about prevalence, severity, dietary patterns and public-health significance within their populations, together with regulatory history and international standards.
Diet matters.
An allergen that is widely consumed in one region may cause a more visible public-health problem there than in a region where people rarely eat it.
This helps explain mustard's prominence in European allergen regulation.
It also demonstrates why calling the UK list "the 14 most common food allergies" is misleading.
The legislation establishes 14 allergens subject to particular information requirements.
It is not a universal league table of the only foods capable of causing serious allergy.
Someone can be severely allergic to a food outside the 14.
The Codex list: where international rules begin to meet
There is an international organisation behind many food standards that most consumers have never heard of.
The Codex Alimentarius Commission, established by the UN Food and Agriculture Organization and World Health Organization, develops international food standards and guidance.
Codex has long maintained provisions concerning foods and ingredients known to cause hypersensitivity, and its work influences national and international food regulation.
In 2025, the Codex Alimentarius Commission adopted a revised general standard for allergen labelling, reflecting substantial work on how priority allergens should be identified internationally. Mustard does not have identical mandatory status in every jurisdiction simply because Codex exists, but Codex provides an important international framework from which governments develop their own rules.
This is another reason EatSafe UK should never create one static "allergen rules around the world" page and forget about it.
Regulation evolves.