Allergens are substances that can cause allergies or intolerances. EU Regulation 1169/2011 lists 14 of them, including gluten, milk, eggs, nuts, fish, crustaceans, soya and sesame, and requires anyone serving food to provide this information for unpackaged dishes too. That includes caterers.
In practice this becomes the allergen matrix: a table that matches each dish on the menu against the 14 allergens. Ask for it with the quote and have the final version attached to the contract. A buffet needs clear labels; a seated meal needs a way to identify the seat of anyone on a special diet, for example with the place card.
How to organise it
Collect allergies and diets with your guests' RSVPs, with name and table, and pass them to the caterer in good time. The guide to special diets explains how; for coeliac disease see the gluten-free entry.
