The answer depends on whether you mean legally recognized allergens or biologically possible ones. In the United States, there are 9 major food allergens that require labeling by law. The European Union recognizes 14. And scientifically, over 1,000 individual allergenic proteins have been cataloged across all sources, with food proteins making up a significant portion. For most people asking this question, the regulatory lists are what matter most, because they determine what shows up (and what doesn’t) on a food label.
The U.S. “Big 9” Allergens
The FDA recognizes nine major food allergens: milk, eggs, fish, crustacean shellfish, tree nuts, peanuts, wheat, soybeans, and sesame. These are the foods that must be clearly identified on any packaged food sold in the United States.
Sesame is the newest addition. The FASTER Act was signed into law in April 2021 and took effect on January 1, 2023, upgrading sesame from an unlabeled ingredient to a mandatory disclosure. Before that, sesame could hide under vague terms like “spices” or “natural flavors” on ingredient lists.
These nine foods account for the vast majority of serious allergic reactions in the U.S., which is why they were singled out. About 6.7% of American adults have a diagnosed food allergy, based on 2024 data from the CDC.
The EU Recognizes 14 Allergens
The European Union requires labeling for 14 allergens, five more than the U.S. list. The overlap includes milk, eggs, fish, crustacean shellfish, tree nuts, peanuts, soybeans, and sesame. The EU also covers cereals containing gluten (wheat, rye, barley, oats, spelt), and sulfites at concentrations of 10 mg/kg or more.
The five allergens on the EU list but not the U.S. list are celery, mustard, lupin, mollusks (like squid and snails, distinct from crustacean shellfish), and sulfites. This means a food product that’s fully compliant with U.S. labeling law could still contain unlabeled allergens that would be flagged in Europe.
Other Countries Have Their Own Lists
Canada recognizes the same core allergens as the U.S. but adds mustard and sulfites. Australia and New Zealand include lupin, molluscan shellfish, and sulfites on top of the common group. Japan prioritizes shrimp, crab, wheat, buckwheat, egg, milk, and peanuts, with buckwheat being a notable addition not found on most Western lists.
These differences aren’t arbitrary. They reflect regional diets and the allergy patterns that follow. Lupin flour is widely used in European and Australian baking, making lupin allergy more common there. Mustard is a staple in Canadian cuisine. Buckwheat is a dietary staple in parts of Asia. The allergens a country regulates tend to mirror the foods its population eats most.
The Full Scientific Count Is Much Higher
The WHO/IUIS Allergen Nomenclature Database, the official global catalog of allergenic proteins, currently lists 1,048 identified allergens. That number covers all sources: pollen, insect venom, animal dander, and food. Food-derived allergens make up a substantial share, spanning everything from common triggers like cow’s milk protein to less familiar ones like kiwi and buckwheat proteins.
The reason regulatory lists are so much shorter than the scientific catalog is practical. Governments focus on the allergens that cause the most frequent and most severe reactions in their populations. Requiring labels for hundreds of rare allergens would make food packaging unreadable without meaningfully improving safety for most people.
Emerging Allergens Beyond the Lists
A growing number of allergic reactions involve foods that don’t appear on any country’s mandatory labeling list. These are sometimes called “emerging allergens,” and their rise is partly driven by shifting diets. As more people adopt plant-based eating, exposure to concentrated pea protein, sunflower seed protein, and coconut has increased, and so have reactions to them.
A Canadian study of children with allergies to non-priority foods found that fruits and vegetables triggered the most reported reactions (59% of cases), followed by seeds other than sesame (22%) and legumes other than peanuts (19%). Among fruits, pineapple, orange, kiwi, mango, banana, and strawberry were flagged by allergists. Among vegetables, corn, zucchini, pepper, and garlic appeared. Reactions to legumes were rated as “probable” true allergic responses, while fruit and vegetable reactions were considered “possible,” suggesting some may involve related but distinct sensitivities like oral allergy syndrome rather than classic food allergy.
One notable finding: 39% of children allergic to non-peanut legumes also had a peanut allergy, pointing to cross-reactivity within the legume family. Health Canada has also flagged that people with mustard allergy may react to foods containing added canola protein, since the two plants are closely related.
How Little Protein Triggers a Reaction
The amount of allergenic protein needed to cause a reaction is startlingly small. Scientists use a measure called the “eliciting dose” to estimate the threshold at which a certain percentage of allergic people will react. The VITAL 3.0 reference doses, widely used in food safety, show just how tiny these amounts are.
For peanut, just 2.1 milligrams of protein is enough to trigger a measurable reaction in about 5% of peanut-allergic individuals. For milk, it’s 2.4 mg. For egg, 2.3 mg. To put that in perspective, a single peanut contains roughly 200 to 300 mg of protein, meaning a fraction of one peanut is more than enough to cause a reaction.
Some allergens have even lower thresholds. Mustard sits at just 0.4 mg, and both cashew and walnut are at 0.8 mg. On the other end of the spectrum, shrimp has a much higher threshold at 280 mg, meaning shrimp-allergic individuals generally tolerate trace amounts better than people with nut or mustard allergies. These differences help explain why some allergies seem to cause reactions from the tiniest cross-contamination while others are more forgiving.
Why the Number Keeps Changing
The count of recognized food allergens isn’t fixed. It shifts as dietary patterns change, as populations are exposed to new protein sources, and as scientific tools improve. Sesame took decades to move from a known clinical problem to a legally recognized U.S. allergen. Lupin has been on the EU list since 2006 but remains absent from most other countries’ regulations.
International bodies like the FAO and WHO are working toward a more unified global approach. Their most recent expert consultation, beginning in 2020, evaluated allergens using three criteria: how common the allergy is, how potent the protein is, and how severe the reactions tend to be. The goal is a standardized priority list that countries can adapt rather than each nation building its own from scratch.
So the short answer: 9 in the U.S., 14 in the EU, and over a thousand if you count every protein science has identified as capable of triggering an allergic response. The number that matters to you depends on where you live, what you eat, and which allergens your body has learned to react to.