What is food allergy?

Food allergy is a reaction of the body's immune system to some common, otherwise harmless, substances in food. A very low level of an allergenic substance may cause a potentially fatal allergic reaction in susceptible individuals. A local survey revealed that about 1 in 20 children in Hong Kong reported having a food allergy. Therefore, it is necessary for all school catering staff to be fully educated about what foods contain allergens, and which foods are suitable for specific dietary needs.

Common food allergens include:

Allergens		Some typical examples of food item in which allergens may be found
Cereals that contain gluten (e.g. wheat, rye, barley and oats)		In foods containing flour, such as bread, pasta, cakes, pastry, meat products, sauces, soups, batter, stock cubes, breadcrumbs, foods dusted with flour, vegetarian products (e.g. plant-based milk)
Crustaceans (e.g. prawns, crabs and lobsters)		In shrimp paste
Eggs		In cakes, mousses, sauces, pasta, quiche, some meat products, mayonnaise, foods brushed with egg
Fish		In some salad dressings, pizzas, relishes, fish sauce, other sauces (e.g. soy and Worcestershire sauces)
Milk		In yoghurt, cream, cheese, butter, milk powders, foods glazed with milk
Molluscs (e.g. mussels and oysters)		In oyster sauce
Tree nuts (e.g. almonds, cashews, hazelnuts, pecans and walnuts)		In sauces, desserts, crackers, bread, ice cream, marzipan, ground almonds, nut oils, vegetarian products (e.g. plant-based milk)
Peanuts		In sauces and spread (e.g. peanut butter), cakes, desserts, groundnut oil, peanut flour
Soybeans		In beancurd (tofu), green soybeans (edamame), fermented beans (douchi), tempeh, soya flour, textured soya protein, certain ice-cream, soy sauces, desserts, meat products, vegetarian products (e.g. plant-based milk and meat)
Sulphur dioxide and sulphites		In meat products, fruit juice drinks, dried fruit and vegetables, wine, beer

Symptoms of food allergy

Symptoms of food allergies usually develop within several minutes to two hours after consuming the offending food.

Common food allergy symptoms include rash, swollen face or lips, shortness of breath and itchy skin.

In most cases, allergic reactions to food are uncomfortable but not particularly dangerous. However, food allergies can cause a potentially fatal reaction known as anaphylactic shock in severe instances. This can present severe symptoms including constriction of the airways, difficulty breathing, severe drop in blood pressure and loss of consciousness. Anaphylactic shock requires immediate emergency care.

Advice for schools and childcare facilities

To minimise the risks of food allergy in children, schools and childcare facilities are advised to:

• Have clear instructions and protocols in place to reduce the risk of cross-contamination of allergens during food preparation.
• Obtain the students' food allergy history along with other medical history at the beginning of each school year.
• Ensure that meals can accommodate children with food allergies and specific dietary requirements.
• Ensure that all catering personnel are informed of the ingredients in the foods they serve. Check the ingredient list for prevalent allergens and take precautions to reduce the risks.
• Read food labels carefully to identify any food or food ingredients of allergic concern.
• Prepare and train staff for handling food allergy emergencies.

Relevant information

•  Clinical management of allergic reactions (issued by the Hospital Authority)