Definitions

Food allergy, food intolerance and coeliac disease

What is a food allergy?

You have a food allergy if your immune system overreacts to a particular protein (an ‘allergen’) in food. Egg, peanuts, milk and nuts contain some of the most common allergens.

Symptoms of an allergic reaction usually come on quickly and, if severe, may include breathing difficulties, vomiting, swelling, collapse and shock.

The term allergen is generally used for any food or food product that causes an allergy or intolerance.

What is a food intolerance?

You may have a food intolerance if you find that a particular type of food often brings on unpleasant symptoms. These may include an upset stomach, rash, headache or other discomfort. However, they do not involve the immune system and usually take a few hours to appear.

Examples include lactose intolerance (where you cannot digest milk properly); migraine brought on by tannins in red wine; or gluten intolerance (which is different from coeliac disease).

What is a food intolerance?

You may have a food intolerance if you find a particular type of food often brings on unpleasant symptoms. These may include an upset stomach, rash, headache or other discomfort. However, they do not involve the immune system and usually take a few hours to appear.

Examples include lactose intolerance (when you cannot digest milk properly); migraine brought on by red wine; or gluten intolerance (which is different from coeliac disease).

What is coeliac disease?

Coeliac disease is triggered by gluten. It is not an allergy or intolerance but an autoimmune disease where your immune system produces antibodies that attack the lining of the gut. This means you cannot absorb certain foods properly, resulting in malnutrition and a range of possible symptoms such as pain, diarrhoea, fatigue and nerve damage. You cannot cure coeliac disease, but you can stay healthy by keeping to a gluten-free diet. Gluten occurs naturally in cereals such as wheat, barley and rye and can easily contaminate other cereals and foodstuffs, such as oats, during processing or packaging.