Allergen categories, explained

Each allergen category flags a major allergen that may be present as an ingredient in a recipe. Some are broad groups, such as tree nuts, while others are specific, such as almonds, walnuts or cashews. That distinction matters: a recipe tagged with a specific nut may still be unsuitable for someone avoiding all tree nuts, and a recipe tagged tree nuts may not specify which nut is used.

A few terms are easy to confuse. Wheat is a cereal grain, while gluten is a protein found in wheat and also in other grains. Fish, crustaceans and molluscs are separate groups, and people’s sensitivities do not always overlap. Sulphur dioxide and sulphites are usually encountered through certain packaged ingredients rather than as something you add by the spoonful. Treat the category as a clear prompt to read the ingredient list with care.

These categories support allergen-aware browsing, but they cannot guarantee safety for an individual. Packaged ingredients can contain allergens as ingredients, processing aids or traces, and labelling rules and wording vary by country. If you cook for someone with an allergy, check every product label each time you buy it, and be cautious with staples that often change formulation.

Cross-contact is a separate issue from ingredients. Shared chopping boards, toasters, baking trays, frying oil and even jars of spreads can transfer small amounts of an allergen. If strict avoidance is needed, it helps to think through the whole preparation path, not just the recipe’s main ingredients.

Start with the ingredient you most need to avoid, then decide whether you need a broad net or a precise one. Broad categories such as tree nuts are useful when you want to avoid a whole family of ingredients, including mixed nuts and nut flours. Specific nut categories are more helpful when you are only avoiding one nut, or when you want to compare recipes that use different nuts for texture and flavour.

For grains, choose wheat when the concern is wheat itself, and gluten when you are avoiding gluten across grains and products that may contain it. For seafood, use fish, crustaceans and molluscs separately, as recipes can include one without the others. For celery, mustard, sesame, soybeans and lupin, remember they can appear in condiments, spice blends and prepared foods, so the ingredient list often matters as much as the headline ingredient.

If you are cooking around an allergy, it can help to browse by Ingredients as well as allergen categories, because many allergens show up through packaged items such as sauces, spreads and baking ingredients. Diet categories can also be useful when you are combining needs, for example avoiding gluten while also keeping a recipe dairy-free, but always confirm against the ingredient list.