What are food allergies, intolerances and coeliac disease?

A food allergy is when the body’s immune system reacts unusually to a specific food, because it mistakenly perceives it as a threat. In children, the most common food allergies are to milk, eggs, peanuts, nuts, fish and shellfish.

Common symptoms of an allergic reaction to food include itching in the mouth, throat or ears, a raised itchy red rash (hives), swelling of the face, around the eyes, lips, tongue and roof of the mouth and vomiting. In the most serious cases, a severe allergic reaction (anaphylaxis, which can include breathing difficulties, light headedness and feeling like you are going to faint) can be life-threatening.

There is no cure for a food allergy, so people with allergies need to avoid the foods to which they are allergic. It is important that children with suspected food allergies see their GP for referral to an allergy clinic for a formal diagnosis. Children with diagnosed severe allergies may be given a device known as an auto-injector pen (e.g. epi-pen) containing a dose of adrenaline to be used in emergencies.

Food intolerances are different from food allergies. Symptoms tend to appear more slowly than in food allergies (often several hours after eating the food), and often include diarrhoea, bloating and stomach cramps. Unlike food allergies, food intolerances are not life-threatening.

Coeliac disease isn’t an allergy or intolerance. It’s an autoimmune disease, where eating gluten triggers the immune system, damaging the lining of the gut and also affecting other parts of the body. Symptoms can include bloating, diarrhoea, nausea, wind, constipation, tiredness, headaches, mouth ulcers, sudden weight loss, hair loss and anaemia.

People with coeliac disease can’t eat foods containing gluten. Gluten is a protein found in wheat, rye and barley. Some people with coeliac disease can’t eat oats, either. Foods containing gluten include bread, pasta, flour, breakfast cereals, cakes, biscuits and pasty. Gluten can also be found in many other processed foods, like soups, sauces and sausages. Traces of gluten can also be found in food where gluten isn’t an ingredient, because of cross-contamination.